All Publications

  • Pyridinic nitrogen induced compressed bilayer graphene for oxygen reduction reaction MATERIALS TODAY ENERGY Solati, N., Cankaya, M., Kahraman, A., Simsek, K., Titus, C., Lee, S., Nordlund, D., Ogasawara, H., Tekin, A., Kaya, S. 2023; 35
  • Correction to "Quantifying the Steric Effect on Metal-Ligand Bonding in Fe Carbene Photosensitizers with Fe 2p3d Resonant Inelastic X-ray Scattering". Inorganic chemistry Kunnus, K., Guo, M., Biasin, E., Larsen, C. B., Titus, C. J., Lee, S. J., Liu, Y., Wärnmark, K., Nordlund, D., Cordones, A. A., Uhlig, J., Gaffney, K. J. 2023

    View details for DOI 10.1021/acs.inorgchem.3c01703

    View details for PubMedID 37314371

  • Regulating Cation Interactions for Zero-Strain and High-Voltage P2-type Na2/3Li1/6Co1/6Mn2/3O2 Layered Oxide Cathodes of Sodium-Ion Batteries. Angewandte Chemie (International ed. in English) Zou, P., Yao, L., Wang, C., Lee, S. J., Li, T., Xin, H. L. 2023: e202304628


    Deep sodium extraction/insertion of sodium cathodes usually causes undesired Jahn-Teller distortion and phase transition, both of which will reduce structural stability and lead to poor long-cycle reliability. Here we report a zero-strain P2- Na2/3Li1/6Co1/6Mn2/3O2 cathode, in which the lithium/cobalt substitution contributes to reinforcing the host structure by reducing the Mn3+/Mn4+ redox, mitigating the Jahn-Teller distortion, and minimizing the lattice change. 94.5% of Na+ in the unit structure can be reversibly cycled with a charge cut-off voltage of 4.5 V (vs. Na+/Na). Impressively, a solid-solution reaction without phase transitions is realized upon deep sodium (de)intercalation, which poses a minimal volume deviation of 0.53%. It attains a high discharge capacity of 178 mAh g-1, a high energy density of 534 Wh kg-1, and excellent capacity retention of 95.8% at 1C after 250 cycles.

    View details for DOI 10.1002/anie.202304628

    View details for PubMedID 37139583

  • Combinatorial Synthesis of Cation-Disordered Manganese Tin Nitride MnSnN2 Thin Films with Magnetic and Semiconducting Properties CHEMISTRY OF MATERIALS Rom, C. L., Smaha, R. W., Melamed, C. L., Schnepf, R., Heinselman, K. N., Mangum, J. S., Lee, S., Lany, S., Schelhas, L. T., Greenaway, A. L., Neilson, J., Bauers, S. R., Tamboli, A. C., Andrew, J. S. 2023
  • P2-Type Moisture-Stable and High-Voltage-Tolerable Cathodes for High-Energy and Long-Life Sodium-Ion Batteries. Nano letters Yuan, S., Yu, L., Qian, G., Xie, Y., Guo, P., Cui, G., Ma, J., Ren, X., Xu, Z., Lee, S., Lee, J., Liu, Y., Ren, Y., Li, L., Tan, G., Liao, X. 2023


    P2-Na0.67Ni0.33Mn0.67O2 represents a promising cathode for Na-ion batteries, but it suffers from severe structural degradation upon storing in a humid atmosphere and cycling at a high cutoff voltage. Here we propose an in situ construction to achieve simultaneous material synthesis and Mg/Sn cosubstitution of Na0.67Ni0.33Mn0.67O2 via one-pot solid-state sintering. The materials exhibit superior structural reversibility and moisture insensitivity. In-operando XRD reveals an essential correlation between cycling stability and phase reversibility, whereas Mg substitution suppressed the P2-O2 phase transition by forming a new Z phase, and Mg/Sn cosubstitution enhanced the P2-Z transition reversibility benefiting from strong Sn-O bonds. DFT calculations disclosed high chemical tolerance to moisture, as the adsorption energy to H2O was lower than that of the pure Na0.67Ni0.33Mn0.67O2. A representative Na0.67Ni0.23Mg0.1Mn0.65Sn0.02O2 cathode exhibits high reversible capacities of 123 mAh g-1 (10 mA g-1), 110 mAh g-1 (200 mA g-1), and 100 mAh g-1 (500 mA g-1) and a high capacity retention of 80% (500 mA g-1, 500 cycles).

    View details for DOI 10.1021/acs.nanolett.2c04465

    View details for PubMedID 36811529

  • Toward High-Performance Mg-S Batteries via a Copper Phosphide Modified Separator. ACS nano Yang, Y., Fu, W., Zhang, D., Ren, W., Zhang, S., Yan, Y., Zhang, Y., Lee, S., Lee, J., Ma, Z., Yang, J., Wang, J., NuLi, Y. 2022


    Magnesium-sulfur (Mg-S) batteries are emerging as a promising alternative to lithium-ion batteries, due to their high energy density and low cost. Unfortunately, current Mg-S batteries typically suffer from the shuttle effect that originates from the dissolution of magnesium polysulfide intermediates, leading to several issues such as rapid capacity fading, large overcharge, severe self-discharge, and potential safety concern. To address these issues, here we harness a copper phosphide (Cu3P) modified separator to realize the adsorption of magnesium polysulfides and catalyzation of the conversion reaction of S and Mg2+ toward stable cycling of Mg-S cells. The bifunctional layer with Cu3P confined in a carbon matrix is coated on a commercial polypropylene membrane to form a porous membrane with high electrolyte wettability and good thermal stability. Density functional theory (DFT) calculations, polysulfide permeability tests, and post-mortem analysis reveal that the catalytic layer can adsorb polysulfides, effectively restraining the shuttle effect and facilitating the reversibility of the Mg-S cells. As a result, the Mg-S cells can achieve a high specific capacity, fast rates (449 mAh g-1 at 0.1 C and 249 mAh g-1 at 1.0 C), and a long cycle life (up to 500 cycles at 0.5 C) and operate even at elevated temperatures.

    View details for DOI 10.1021/acsnano.2c09302

    View details for PubMedID 36583574

  • Tuning discharge voltage by Schottky electron barrier in P2-Na2/ 3Mg0.205Ni0.1Fe0.05Mn0.645O2 ENERGY STORAGE MATERIALS Wang, Y., Shadike, Z., Fitzhugh, W., Wu, F., Lee, S., Lee, J., Chen, X., Long, Y., Hu, E., Li, X. 2023; 55: 587-596
  • Compositionally complex doping for zero-strain zero-cobalt layered cathodes. Nature Zhang, R., Wang, C., Zou, P., Lin, R., Ma, L., Yin, L., Li, T., Xu, W., Jia, H., Li, Q., Sainio, S., Kisslinger, K., Trask, S. E., Ehrlich, S. N., Yang, Y., Kiss, A. M., Ge, M., Polzin, B. J., Lee, S. J., Xu, W., Ren, Y., Xin, H. L. 2022


    The high volatility of the price ofcobalt and thegeopolitical limitations of cobalt mining have made the elimination of Co a pressing need for the automotive industry1. Owing to their high energy density and low-cost advantages, high-Ni and low-Co or Co-free(zero-Co) layered cathodes havebecome the most promising cathodes for next-generation lithium-ion batteries2,3. However, current high-Ni cathode materials, without exception, sufferseverely from their intrinsic thermal and chemo-mechanical instabilities and insufficient cycle life. Here, by using a new compositionally complex (high-entropy) doping strategy, we successfully fabricate a high-Ni, zero-Co layered cathode that has extremely high thermal and cycling stability. Combining X-ray diffraction, transmission electron microscopy and nanotomography, we find that the cathode exhibits nearly zero volumetric change over a wide electrochemical window, resulting in greatly reduced lattice defects and local strain-induced cracks. In-situ heating experiments reveal that the thermal stability of the new cathode is significantly improved, reaching the level of the ultra-stable NMC-532. Owing to the considerably increased thermal stability and the zero volumetric change, it exhibits greatly improved capacity retention. This work, by resolving the long-standing safety and stability concerns for high-Ni, zero-Co cathode materials, offers a commercially viable cathode for safe, long-life lithium-ion batteriesand a universal strategy forsuppressing strain and phase transformation in intercalation electrodes.

    View details for DOI 10.1038/s41586-022-05115-z

    View details for PubMedID 36131017

  • A broken translational symmetry state in an infinite-layer nickelate NATURE PHYSICS Rossi, M., Osada, M., Choi, J., Agrestini, S., Jost, D., Lee, Y., Lu, H., Wang, B., Lee, K., Nag, A., Chuang, Y., Kuo, C., Lee, S., Moritz, B., Devereaux, T. P., Shen, Z., Lee, J., Zhou, K., Hwang, H. Y., Lee, W. 2022
  • Synthesis and electronic properties of epitaxial SrNiO3/SrTiO3 superlattices PHYSICAL REVIEW MATERIALS Wang, L., Zhao, J., Kuo, C., Matthews, B. E., Oostrom, M. T., Spurgeon, S. R., Yang, Z., Bowden, M. E., Wangoh, L. W., Lee, S., Lee, J., Guo, E., Wang, J., Chambers, S. A., Du, Y. 2022; 6 (7)
  • Orientation-Controlled Anisotropy in Single Crystals of Quasi-1D BaTiS3 CHEMISTRY OF MATERIALS Zhao, B., Bin Hoque, M., Jung, G., Mei, H., Singh, S., Ren, G., Milich, M., Zhao, Q., Wang, N., Chen, H., Niu, S., Lee, S., Kuo, C., Lee, J., Tomko, J. A., Wang, H., Kats, M. A., Mishra, R., Hopkins, P. E., Ravichandran, J. 2022
  • Revisiting the capacity-fading mechanism of P2-type sodium layered oxide cathode materials during high-voltage cycling JOURNAL OF ENERGY CHEMISTRY Jiang, M., Qian, G., Liao, X., Ren, Z., Dong, Q., Meng, D., Cui, G., Yuan, S., Lee, S., Qin, T., Liu, X., Shen, Y., He, Y., Chen, L., Liu, Y., Li, L., Ma, Z. 2022; 69: 16-25
  • Structural, Dynamic, and Chemical Complexities in Zinc Anode of an Operating Aqueous Zn-Ion Battery ADVANCED ENERGY MATERIALS Qian, G., Zan, G., Li, J., Lee, S., Wang, Y., Zhu, Y., Gul, S., Vine, D. J., Lewis, S., Yun, W., Ma, Z., Pianetta, P., Lee, J., Li, L., Liu, Y. 2022
  • Generic character of charge and spin density waves in superconducting cuprates. Proceedings of the National Academy of Sciences of the United States of America Lee, S., Huang, E. W., Johnson, T. A., Guo, X., Husain, A. A., Mitrano, M., Lu, K., Zakrzewski, A. V., de la Peña, G. A., Peng, Y., Huang, H., Lee, S. J., Jang, H., Lee, J. S., Joe, Y. I., Doriese, W. B., Szypryt, P., Swetz, D. S., Chi, S., Aczel, A. A., MacDougall, G. J., Kivelson, S. A., Fradkin, E., Abbamonte, P. 2022; 119 (15): e2119429119


    SignificanceThe essential physics of the cuprate high-temperature superconductors have been a central focus of condensed-matter physics for more than three decades. Although initially controversial, it is now clear that a ubiquitous tendency toward charge-density-wave (CDW) order is intertwined with the superconductivity. However, this manifests differently in distinct cuprates. On the basis of extensive X-ray and neutron scattering studies of the temperature and doping dependence of the CDW and spin-density-wave (SDW) correlations in one representative cuprate and a comparison with existing studies on other cuprates, we show that there plausibly is a single, preferred CDW order at the microscale, whose manifestation at low temperatures is modified in predictable ways by material-specific details, including its interaction with SDW order.

    View details for DOI 10.1073/pnas.2119429119

    View details for PubMedID 35377791

  • Characterization of photoinduced normal state through charge density wave in superconducting YBa2Cu3O6.67. Science advances Jang, H., Song, S., Kihara, T., Liu, Y., Lee, S., Park, S., Kim, M., Kim, H., Coslovich, G., Nakata, S., Kubota, Y., Inoue, I., Tamasaku, K., Yabashi, M., Lee, H., Song, C., Nojiri, H., Keimer, B., Kao, C., Lee, J. 2022; 8 (6): eabk0832


    The normal state of high-Tc cuprates has been considered one of the essential topics in high-temperature superconductivity research. However, compared to the high magnetic field study of it, understanding a photoinduced normal state remains elusive. Here, we explore a photoinduced normal state of YBa2Cu3O6.67 through a charge density wave (CDW) with time-resolved resonant soft x-ray scattering, as well as a high magnetic field x-ray scattering. In the nonequilibrium state where people predict a quenched superconducting state based on the previous optical spectroscopies, we experimentally observed a similar analogy to the competition between superconductivity and CDW shown in the equilibrium state. We further observe that the broken pairing states in the superconducting CuO2 plane via the optical pump lead to nucleation of three-dimensional CDW precursor correlation. Ultimately, these findings provide a critical clue that the characteristics of the photoinduced normal state show a solid resemblance to those under magnetic fields in equilibrium conditions.

    View details for DOI 10.1126/sciadv.abk0832

    View details for PubMedID 35138893

  • Thermal-healing of lattice defects for high-energy single-crystalline battery cathodes. Nature communications Li, S., Qian, G., He, X., Huang, X., Lee, S., Jiang, Z., Yang, Y., Wang, W., Meng, D., Yu, C., Lee, J., Chu, Y. S., Ma, Z., Pianetta, P., Qiu, J., Li, L., Zhao, K., Liu, Y. 2022; 13 (1): 704


    Single-crystalline nickel-rich cathodes are a rising candidate with great potential for high-energy lithium-ion batteries due to their superior structural and chemical robustness in comparison with polycrystalline counterparts. Within the single-crystalline cathode materials, the lattice strain and defects have significant impacts on the intercalation chemistry and, therefore, play a key role in determining the macroscopic electrochemical performance. Guided by our predictive theoretical model, we have systematically evaluated the effectiveness of regaining lost capacity by modulating the lattice deformation via an energy-efficient thermal treatment at different chemical states. We demonstrate that the lattice structure recoverability is highly dependent on both the cathode composition and the state of charge, providing clues to relieving the fatigued cathode crystal for sustainable lithium-ion batteries.

    View details for DOI 10.1038/s41467-022-28325-5

    View details for PubMedID 35121768

  • Metastable Brominated Nanodiamond Surface Enables Room Temperature and Catalysis-Free Amine Chemistry. The journal of physical chemistry letters Melendrez, C., Lopez-Rosas, J. A., Stokes, C. X., Cheung, T. C., Lee, S., Titus, C. J., Valenzuela, J., Jeanpierre, G., Muhammad, H., Tran, P., Sandoval, P. J., Supreme, T., Altoe, V., Vavra, J., Raabova, H., Vanek, V., Sainio, S., Doriese, W. B., O'Neil, G. C., Swetz, D. S., Ullom, J. N., Irwin, K., Nordlund, D., Cigler, P., Wolcott, A. 1800: 1147-1158


    Bromination of high-pressure, high-temperature (HPHT) nanodiamond (ND) surfaces has not been explored and can open new avenues for increased chemical reactivity and diamond lattice covalent bond formation. The large bond dissociation energy of the diamond lattice-oxygen bond is a challenge that prevents new bonds from forming, and most researchers simply use oxygen-terminated NDs (alcohols and acids) as reactive species. In this work, we transformed a tertiary-alcohol-rich ND surface to an amine surface with 50% surface coverage and was limited by the initial rate of bromination. We observed that alkyl bromide moieties are highly labile on HPHT NDs and are metastable as previously found using density functional theory. The strong leaving group properties of the alkyl bromide intermediate were found to form diamond-nitrogen bonds at room temperature and without catalysts. This robust pathway to activate a chemically inert ND surface broadens the modalities for surface termination, and the unique surface properties of brominated and aminated NDs are impactful to researchers for chemically tuning diamond for quantum sensing or biolabeling applications.

    View details for DOI 10.1021/acs.jpclett.1c04090

    View details for PubMedID 35084184

  • Quantifying the Steric Effect on Metal-Ligand Bonding in Fe Carbene Photosensitizers with Fe 2p3d Resonant Inelastic X-ray Scattering. Inorganic chemistry Kunnus, K., Guo, M., Biasin, E., Larsen, C. B., Titus, C. J., Lee, S. J., Nordlund, D., Cordones, A. A., Uhlig, J., Gaffney, K. J. 1800


    Understanding the electronic structure and chemical bonding of transition metal complexes is important for improving the function of molecular photosensitizers and catalysts. We have utilized X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) at the Fe L3 edge to investigate the electronic structure of two Fe N-heterocyclic carbene complexes with similar chemical structures but different steric effects and contrasting excited-state dynamics: [Fe(bmip)2]2+ and [Fe(btbip)2]2+, bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)pyridine and btbip = 2,6-bis(3-tert-butyl-imidazole-1-ylidene)pyridine. In combination with charge transfer multiplet and ab initio calculations, we quantified how changes in Fe-carbene bond length due to steric effects modify the metal-ligand bonding, including sigma/pi donation and pi back-donation. We find that sigma donation is significantly stronger in [Fe(bmip)2]2+, whereas the pi back-donation is similar in both complexes. The resulting stronger ligand field and nephelauxetic effect in [Fe(bmip)2]2+ lead to approximately 1 eV destabilization of the quintet metal-centered 5T2g excited state compared to [Fe(btbip)2]2+, providing an explanation for the absence of a photoinduced 5T2g population and a longer metal-to-ligand charge-transfer excited-state lifetime in [Fe(bmip)2]2+. This work demonstrates how combined modeling of XAS and RIXS spectra can be utilized to understand the electronic structure of transition metal complexes governed by correlated electrons and donation/back-donation interactions.

    View details for DOI 10.1021/acs.inorgchem.1c03124

    View details for PubMedID 35029978

  • The role of structural defects in commercial lithium-ion batteries CELL REPORTS PHYSICAL SCIENCE Qian, G., Monaco, F., Meng, D., Lee, S., Zan, G., Li, J., Karpov, D., Gul, S., Vine, D., Stripe, B., Zhang, J., Lee, J., Ma, Z., Yun, W., Pianetta, P., Yu, X., Li, L., Cloeten, P., Liu, Y. 2021; 2 (9)
  • Multiphase, Multiscale Chemomechanics at Extreme Low Temperatures: Battery Electrodes for Operation in a Wide Temperature Range ADVANCED ENERGY MATERIALS Li, J., Li, S., Zhang, Y., Yang, Y., Russi, S., Qian, G., Mu, L., Lee, S., Yang, Z., Lee, J., Pianetta, P., Qiu, J., Ratner, D., Cloetens, P., Zhao, K., Lin, F., Liu, Y. 2021
  • Chemical Modulation of Local Transition Metal Environment Enables Reversible Oxygen Redox in Mn-Based Layered Cathodes ACS ENERGY LETTERS Rahman, M., McGuigan, S., Li, S., Gao, L., Hou, D., Yang, Z., Xu, Z., Lee, S., Sun, C., Liu, J., Huang, X., Xiao, X., Chu, Y., Sainio, S., Nordlund, D., Kong, X., Liu, Y., Lin, F. 2021; 6 (8): 2882-2890
  • Reversible Mn/Cr dual redox in cation-disordered Li-excess cathode materials for stable lithium ion batteries ACTA MATERIALIA Zheng, X., Xu, Z., Li, S., Zhang, Y., Zhang, J., Kuai, C., Tao, L., Rahman, M., Zhang, Y., Lee, S., Sun, C., Li, L., Hu, W., Nordlund, D., Liu, J., Liu, Y., Lin, F. 2021; 212
  • Selective dopant segregation modulates mesoscale reaction kinetics in layered transition metal oxide NANO ENERGY Qian, G., Huang, H., Hou, F., Wang, W., Wang, Y., Lin, J., Lee, S., Yan, H., Chu, Y. S., Pianetta, P., Huang, X., Ma, Z., Li, L., Liu, Y. 2021; 84
  • Depth-dependent valence stratification driven by oxygen redox in lithium-rich layered oxide. Nature communications Zhang, J., Wang, Q., Li, S., Jiang, Z., Tan, S., Wang, X., Zhang, K., Yuan, Q., Lee, S., Titus, C. J., Irwin, K. D., Nordlund, D., Lee, J., Pianetta, P., Yu, X., Xiao, X., Yang, X., Hu, E., Liu, Y. 2020; 11 (1): 6342


    Lithium-rich nickel-manganese-cobalt (LirNMC) layered material is a promising cathode for lithium-ion batteries thanks to its large energy density enabled by coexisting cation and anion redox activities. It however suffers from a voltage decay upon cycling, urging for an in-depth understanding of the particle-level structure and chemical complexity. In this work, we investigate the Li1.2Ni0.13Mn0.54Co0.13O2 particles morphologically, compositionally, and chemically in three-dimensions. While the composition is generally uniform throughout the particle, the charging induces a strong depth dependency in transition metal valence. Such a valence stratification phenomenon is attributed to the nature of oxygen redox which is very likely mostly associated with Mn. The depth-dependent chemistry could be modulated by the particles' core-multi-shell morphology, suggesting a structural-chemical interplay. These findings highlight the possibility of introducing a chemical gradient to address the oxygen-loss-induced voltage fade in LirNMC layered materials.

    View details for DOI 10.1038/s41467-020-20198-w

    View details for PubMedID 33311507

  • Operando Tailoring of Defects and Strains in Corrugated beta-Ni(OH)2 Nanosheets for Stable and High-Rate Energy Storage. Advanced materials (Deerfield Beach, Fla.) Li, S., Sharma, N., Yu, C., Zhang, Y., Wan, G., Fu, R., Huang, H., Sun, X., Lee, S., Lee, J., Nordlund, D., Pianetta, P., Zhao, K., Liu, Y., Qiu, J. 2020: e2006147


    Nickel hydroxide represents a technologically important material for energy storage, such as hybrid supercapacitors. It has two different crystallographic polymorphs, alpha- and beta-Ni(OH)2 , showing advantages in either theoretical capacity or cycling/rate performance, manifesting a trade-off trend that needs to be optimized for practical applications. Here, the synergistic superiorities in both activity and stability of corrugated beta-Ni(OH)2 nanosheets are demonstrated through an electrochemical abuse approach. With 91% capacity retention after 10000 cycles, the corrugated beta-Ni(OH)2 nanosheets can deliver a gravimetric capacity of 457 C g-1 at a high current density of 30 A g-1 , which is nearly two and four times that of the regular alpha- and beta-Ni(OH)2 , respectively. Operando spectroscopy and finite element analysis reveal that greatly enhanced chemical activity and structural robustness can be attributed to the in situ tailored lattice defects and the strain-induced highly curved micromorphology. This work demonstrates a multi-scale defect-and-strain co-design strategy, which is helpful for rational design and tuned fabrication of next-generation electrode materials for stable and high-rate energy storage.

    View details for DOI 10.1002/adma.202006147

    View details for PubMedID 33270282

  • Mutual modulation between surface chemistry and bulk microstructure within secondary particles of nickel-rich layered oxides. Nature communications Li, S., Jiang, Z., Han, J., Xu, Z., Wang, C., Huang, H., Yu, C., Lee, S., Pianetta, P., Ohldag, H., Qiu, J., Lee, J., Lin, F., Zhao, K., Liu, Y. 2020; 11 (1): 4433


    Surface lattice reconstruction is commonly observed in nickel-rich layered oxide battery cathode materials, causing unsatisfactory high-voltage cycling performance. However, the interplay of the surface chemistry and the bulk microstructure remains largely unexplored due to the intrinsic structural complexity and the lack of integrated diagnostic tools for a thorough investigation at complementary length scales. Herein, by combining nano-resolution X-ray probes in both soft and hard X-ray regimes, we demonstrate correlative surface chemical mapping and bulk microstructure imaging over a single charged LiNi0.8Mn0.1Co0.1O2 (NMC811) secondary particle. We reveal that the sub-particle regions with more micro cracks are associated with more severe surface degradation. A mechanism of mutual modulation between the surface chemistry and the bulk microstructure is formulated based on our experimental observations and finite element modeling. Such a surface-to-bulk reaction coupling effect is fundamentally important for the design of the next generation battery cathode materials.

    View details for DOI 10.1038/s41467-020-18278-y

    View details for PubMedID 32895388

  • Detection of the Chiral Spin Structure in Ferromagnetic SrRuO3 Thin Film ACS APPLIED MATERIALS & INTERFACES Huang, H., Lee, S., Kim, B., Sohn, B., Kim, C., Kao, C., Lee, J. 2020; 12 (33): 37757–63


    SrRuO3 (SRO) thin films and their heterostructure have attracted much attention because of the recently demonstrated fascinating properties, such as topological Hall effect and skyrmions. Critical to the understanding of those SRO properties is the study of the spin configuration. Here, we conduct resonant soft X-ray scattering (RSXS) at the oxygen K edge to investigate the spin configuration of a four-unit-cell SRO film that was grown epitaxially on a single-crystal SrTiO3. The RSXS signal under a magnetic field (∼0.4 tesla) clearly shows a magnetic dichroism pattern around the specular reflection. Model calculations on the RSXS signal demonstrate that the magnetic dichroism pattern originates from a Néel-type chiral spin structure in this SRO thin film. We believe that the observed spin structure of the SRO system is a critical piece of information for understanding its intriguing magnetic and transport properties.

    View details for DOI 10.1021/acsami.0c10545

    View details for Web of Science ID 000563074900095

    View details for PubMedID 32696641

  • Chemical control of competing electron transfer pathways in iron tetracyano-polypyridyl photosensitizers CHEMICAL SCIENCE Kunnus, K., Li, L., Titus, C., Lee, S., Reinhard, M. E., Koroidov, S., Kjaer, K. S., Hong, K., Ledbetter, K., Doriese, W. B., O'Neil, G. C., Swetz, D. S., Ullom, J., Li, D., Irwin, K., Nordlund, D., Cordones, A., Gaffney, K. J. 2020; 11 (17): 4360–73

    View details for DOI 10.1039/c9sc06272f

    View details for Web of Science ID 000532365500005

  • Enabling Stable Cycling of 4.2 V High-Voltage All-Solid-State Batteries with PEO-Based Solid Electrolyte ADVANCED FUNCTIONAL MATERIALS Qiu, J., Liu, X., Chen, R., Li, Q., Wang, Y., Chen, P., Gan, L., Lee, S., Nordlund, D., Liu, Y., Yu, X., Bai, X., Li, H., Chen, L. 2020; 30 (22)
  • Chemical control of competing electron transfer pathways in iron tetracyano-polypyridyl photosensitizers. Chemical science Kunnus, K., Li, L., Titus, C. J., Lee, S. J., Reinhard, M. E., Koroidov, S., Kjær, K. S., Hong, K., Ledbetter, K., Doriese, W. B., O'Neil, G. C., Swetz, D. S., Ullom, J. N., Li, D., Irwin, K., Nordlund, D., Cordones, A. A., Gaffney, K. J. 2020; 11 (17): 4360-4373


    Photoinduced intramolecular electron transfer dynamics following metal-to-ligand charge-transfer (MLCT) excitation of [Fe(CN)4(2,2'-bipyridine)]2- (1), [Fe(CN)4(2,3-bis(2-pyridyl)pyrazine)]2- (2) and [Fe(CN)4(2,2'-bipyrimidine)]2- (3) were investigated in various solvents with static and time-resolved UV-Visible absorption spectroscopy and Fe 2p3d resonant inelastic X-ray scattering (RIXS). This series of polypyridyl ligands, combined with the strong solvatochromism of the complexes, enables the 1MLCT vertical energy to be varied from 1.64 eV to 2.64 eV and the 3MLCT lifetime to range from 180 fs to 67 ps. The 3MLCT lifetimes in 1 and 2 decrease exponentially as the MLCT energy increases, consistent with electron transfer to the lowest energy triplet metal-centred (3MC) excited state, as established by the Tanabe-Sugano analysis of the Fe 2p3d RIXS data. In contrast, the 3MLCT lifetime in 3 changes non-monotonically with MLCT energy, exhibiting a maximum. This qualitatively distinct behaviour results from a competing 3MLCT → ground state (GS) electron transfer pathway that exhibits energy gap law behaviour. The 3MLCT → GS pathway involves nuclear tunnelling for the high-frequency polypyridyl breathing mode (hν = 1530 cm-1), which is most displaced for complex 3, making this pathway significantly more efficient. Our study demonstrates that the excited state relaxation mechanism of Fe polypyridyl photosensitizers can be readily tuned by ligand and solvent environment. Furthermore, our study reveals that extending charge transfer lifetimes requires control of the relative energies of the 3MLCT and the 3MC states and suppression of the intramolecular distortion of the acceptor ligand in the 3MLCT excited state.

    View details for DOI 10.1039/c9sc06272f

    View details for PubMedID 34122894

    View details for PubMedCentralID PMC8159445

  • Operando Revealing Dynamic Reconstruction of NiCo Carbonate Hydroxide for High-Rate Energy Storage JOULE Li, S., Zhang, Y., Liu, N., Yu, C., Lee, S., Zhou, S., Fu, R., Yang, J., Guo, W., Huang, H., Lee, J., Wang, C., Kim, T., Nordlund, D., Pianetta, P., Du, X., Zhao, J., Liu, Y., Qiu, J. 2020; 4 (3): 673–87
  • The Myth of d8 Copper(III). Journal of the American Chemical Society DiMucci, I. M., Lukens, J. T., Chatterjee, S., Carsch, K. M., Titus, C. J., Lee, S. J., Nordlund, D., Betley, T. A., MacMillan, S. N., Lancaster, K. M. 2019


    Seventeen Cu complexes with formal oxidation states ranging from CuI to CuIII are investigated through the use of multiedge X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations. Analysis reveals that the metal-ligand bonding in high-valent, formally CuIII species is extremely covalent, resulting in Cu K-edge and L2,3-edge spectra whose features have energies that complicate physical oxidation state assignment. Covalency analysis of the Cu L2,3-edge data reveals that all formally CuIII species have significantly diminished Cu d-character in their lowest unoccupied molecular orbitals (LUMOs). DFT calculations provide further validation of the orbital composition analysis, and excellent agreement is found between the calculated and experimental results. The finding that Cu has limited capacity to be oxidized necessitates localization of electron hole character on the supporting ligands; consequently, the physical d8 description for these formally CuIII species is inaccurate. This study provides an alternative explanation for the competence of formally CuIII species in transformations that are traditionally described as metal-centered, 2-electron CuI/CuIII redox processes.

    View details for DOI 10.1021/jacs.9b09016

    View details for PubMedID 31710466

  • Synthesis of a copper-supported triplet nitrene complex pertinent to copper-catalyzed amination. Science (New York, N.Y.) Carsch, K. M., DiMucci, I. M., Iovan, D. A., Li, A., Zheng, S., Titus, C. J., Lee, S. J., Irwin, K. D., Nordlund, D., Lancaster, K. M., Betley, T. A. 2019; 365 (6458): 1138–43


    Terminal copper-nitrenoid complexes have inspired interest in their fundamental bonding structures as well as their putative intermediacy in catalytic nitrene-transfer reactions. Here, we report that aryl azides react with a copper(I) dinitrogen complex bearing a sterically encumbered dipyrrin ligand to produce terminal copper nitrene complexes with near-linear, short copper-nitrenoid bonds [1.745(2) to 1.759(2) angstroms]. X-ray absorption spectroscopy and quantum chemistry calculations reveal a predominantly triplet nitrene adduct bound to copper(I), as opposed to copper(II) or copper(III) assignments, indicating the absence of a copper-nitrogen multiple-bond character. Employing electron-deficient aryl azides renders the copper nitrene species competent for alkane amination and alkene aziridination, lending further credence to the intermediacy of this species in proposed nitrene-transfer mechanisms.

    View details for DOI 10.1126/science.aax4423

    View details for PubMedID 31515388

  • Use of Transition Models to Design High Performance TESs for the LCLS-II Soft X-Ray Spectrometer IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Morgan, K. M., Becker, D. T., Bennett, D., Doriesee, W. B., Gard, J. D., Irwin, K. D., Lee, S., Li, D., Mates, J. B., Pappas, C. G., Schmidt, D. R., Titus, C. J., Van Winkle, D. D., Ullom, J. N., Wessels, A., Swetz, D. S. 2019; 29 (5)
  • In-situ functionalization of tetrahedral amorphous carbon by filtered cathodic arc deposition AIP ADVANCES Sainio, S., Wester, N., Titus, C. J., Nordlund, D., Lee, S., Koskinen, J., Laurila, T. 2019; 9 (8)

    View details for DOI 10.1063/1.5113484

    View details for Web of Science ID 000483883400075

  • Quantification of Heterogeneous Degradation in Li-Ion Batteries ADVANCED ENERGY MATERIALS Yang, Y., Xu, R., Zhang, K., Lee, S., Mu, L., Liu, P., Waters, C. K., Spence, S., Xu, Z., Wei, C., Kautz, D. J., Yuan, Q., Dong, Y., Yu, Y., Xiao, X., Lee, H., Pianetta, P., Cloetens, P., Lee, J., Zhao, K., Lin, F., Liu, Y. 2019; 9 (25)
  • Hybrid X-ray Spectroscopy-Based Approach To Acquire Chemical and Structural Information of Single-Walled Carbon Nanotubes with Superior Sensitivity JOURNAL OF PHYSICAL CHEMISTRY C Sainio, S., Wester, N., Titus, C. J., Liao, Y., Zhang, Q., Nordlund, D., Sokaras, D., Lee, S., Irwin, K. D., Doriese, W. B., O'Neil, G. C., Swetz, D. S., Ullom, J. N., Kauppinen, E., Laurila, T., Koskinen, J. 2019; 123 (10): 6114–20
  • Surface-to-Bulk Redox Coupling through Thermally Driven Li Redistribution in Li- and Mn-Rich Layered Cathode Materials. Journal of the American Chemical Society Li, S. n., Lee, S. J., Wang, X. n., Yang, W. n., Huang, H. n., Swetz, D. S., Doriese, W. B., O'Neil, G. C., Ullom, J. N., Titus, C. J., Irwin, K. D., Lee, H. K., Nordlund, D. n., Pianetta, P. n., Yu, C. n., Qiu, J. n., Yu, X. n., Yang, X. Q., Hu, E. n., Lee, J. S., Liu, Y. n. 2019


    Li- and Mn-rich (LMR) layered cathode materials have demonstrated impressive capacity and specific energy density thanks to their intertwined redox centers including transition metal cations and oxygen anions. Although tremendous efforts have been devoted to the investigation of the electrochemically driven redox evolution in LMR cathode at ambient temperature, their behavior under a mildly elevated temperature (up to ∼100 °C), with or without electrochemical driving force, remains largely unexplored. Here we show a systematic study of the thermally driven surface-to-bulk redox coupling effect in charged Li1.2Ni0.15Co0.1Mn0.55O2. We for the first time observed a charge transfer between the bulk oxygen anions and the surface transition metal cations under ∼100 °C, which is attributed to the thermally driven redistribution of Li ions. This finding highlights the nonequilibrium state and dynamic nature of the LMR material at deeply delithiated state upon a mild temperature perturbation.

    View details for DOI 10.1021/jacs.9b05349

    View details for PubMedID 31287957

  • Use of Transition Models to Design High Performance TESs for the LCLS-II Soft X-Ray Spectrometer. IEEE transactions on applied superconductivity : a publication of the IEEE Superconductivity Committee Morgan, K. M., Becker, D. T., Bennett, D. A., Doriese, W. B., Gard, J. D., Irwin, K. D., Lee, S. J., Li, D., Mates, J. A., Pappas, C. G., Schmidt, D. R., Titus, C. J., Van Winkle, D. D., Ullom, J. N., Wessels, A., Swetz, D. S. 2019; 29 (5)


    We are designing an array of transition-edge sensor (TES) microcalorimeters for a soft X-ray spectrometer at the Linac Coherent Light Source at SLAC National Accelerator Laboratory to coincide with upgrades to the free electron laser facility. The complete spectrometer will have 1000 TES pixels with energy resolution of 0.5 eV full-width at half-maximum (FWHM) for incident energies below 1 keV while maintaining pulse decay-time constants shorter than 100 μs. Historically, TES pixels have often been designed for a particular scientific application via a combination of simple scaling relations and trial-and-error experimentation with device geometry. We have improved upon this process by using our understanding of transition physics to guide TES design. Using the two-fluid approximation of the phase-slip line model for TES resistance, we determine how the geometry and critical temperature of a TES will affect the shape of the transition. We have used these techniques to design sensors with a critical temperature of 55 mK. The best sensors achieve an energy resolution of 0.75 eV FWHM at 1.25 keV. Building upon this result, we show how the next generation of sensors can be designed to reach our goal of 0.5 eV resolution.

    View details for DOI 10.1109/tasc.2019.2903032

    View details for PubMedID 33456289

    View details for PubMedCentralID PMC7808210

  • Soft X-ray spectroscopy with transition-edge sensors at Stanford Synchrotron Radiation Lightsource beamline 10-1. The Review of scientific instruments Lee, S. J., Titus, C. J., Alonso Mori, R. n., Baker, M. L., Bennett, D. A., Cho, H. M., Doriese, W. B., Fowler, J. W., Gaffney, K. J., Gallo, A. n., Gard, J. D., Hilton, G. C., Jang, H. n., Joe, Y. I., Kenney, C. J., Knight, J. n., Kroll, T. n., Lee, J. S., Li, D. n., Lu, D. n., Marks, R. n., Minitti, M. P., Morgan, K. M., Ogasawara, H. n., O'Neil, G. C., Reintsema, C. D., Schmidt, D. R., Sokaras, D. n., Ullom, J. N., Weng, T. C., Williams, C. n., Young, B. A., Swetz, D. S., Irwin, K. D., Nordlund, D. n. 2019; 90 (11): 113101


    We present results obtained with a new soft X-ray spectrometer based on transition-edge sensors (TESs) composed of Mo/Cu bilayers coupled to bismuth absorbers. This spectrometer simultaneously provides excellent energy resolution, high detection efficiency, and broadband spectral coverage. The new spectrometer is optimized for incident X-ray energies below 2 keV. Each pixel serves as both a highly sensitive calorimeter and an X-ray absorber with near unity quantum efficiency. We have commissioned this 240-pixel TES spectrometer at the Stanford Synchrotron Radiation Lightsource beamline 10-1 (BL 10-1) and used it to probe the local electronic structure of sample materials with unprecedented sensitivity in the soft X-ray regime. As mounted, the TES spectrometer has a maximum detection solid angle of 2 × 10-3 sr. The energy resolution of all pixels combined is 1.5 eV full width at half maximum at 500 eV. We describe the performance of the TES spectrometer in terms of its energy resolution and count-rate capability and demonstrate its utility as a high throughput detector for synchrotron-based X-ray spectroscopy. Results from initial X-ray emission spectroscopy and resonant inelastic X-ray scattering experiments obtained with the spectrometer are presented.

    View details for DOI 10.1063/1.5119155

    View details for PubMedID 31779391

  • Thermally driven mesoscale chemomechanical interplay in Li0.5Ni0.6Mn0.2Co0.2O2 cathode materials JOURNAL OF MATERIALS CHEMISTRY A Wei, C., Zhang, Y., Lee, S., Mu, L., Liu, J., Wang, C., Yang, Y., Doeff, M., Pianetta, P., Nordlund, D., Du, X., Tian, Y., Zhao, K., Lee, J., Lin, F., Liu, Y. 2018; 6 (45): 23055–61

    View details for DOI 10.1039/c8ta08973f

    View details for Web of Science ID 000451738200071

  • L-edge spectroscopy of dilute, radiation-sensitive systems using a transition-edge-sensor array JOURNAL OF CHEMICAL PHYSICS Titus, C. J., Baker, M. L., Lee, S., Cho, H., Doriese, W. B., Fowler, J. W., Gaffney, K., Gard, J. D., Hilton, G. C., Kenney, C., Knight, J., Li, D., Marks, R., Minitti, M. P., Morgan, K. M., O'Neil, G. C., Reintsema, C. D., Schmidt, D. R., Sokaras, D., Swetz, D. S., Ullom, J. N., Weng, T., Williams, C., Young, B. A., Irwin, K. D., Solomon, E. I., Nordlund, D. 2017; 147 (21): 214201


    We present X-ray absorption spectroscopy and resonant inelastic X-ray scattering (RIXS) measurements on the iron L-edge of 0.5 mM aqueous ferricyanide. These measurements demonstrate the ability of high-throughput transition-edge-sensor (TES) spectrometers to access the rich soft X-ray (100-2000 eV) spectroscopy regime for dilute and radiation-sensitive samples. Our low-concentration data are in agreement with high-concentration measurements recorded by grating spectrometers. These results show that soft-X-ray RIXS spectroscopy acquired by high-throughput TES spectrometers can be used to study the local electronic structure of dilute metal-centered complexes relevant to biology, chemistry, and catalysis. In particular, TES spectrometers have a unique ability to characterize frozen solutions of radiation- and temperature-sensitive samples.

    View details for PubMedID 29221417

    View details for PubMedCentralID PMC5720893

  • High count-rate study of two TES x-ray microcalorimeters with different transition temperatures SUPERCONDUCTOR SCIENCE & TECHNOLOGY Lee, S., Adams, J. S., Bandler, S. R., Betancourt-Martinez, G. L., Chervenak, J. A., Eckart, M. E., Finkbeiner, F. M., Kelley, R. L., Kilbourne, C. A., Porter, F. S., Sadleir, J. E., Smith, S. J., Wassell, E. J. 2017; 30 (10)
  • Parametric Characterization of TES Detectors Under DC Bias IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Chiao, M. P., Smith, S. J., Kilbourne, C. A., Adams, J. S., Bandler, S. R., Betancourt-Martinez, G. L., Chervenak, J. A., Datesman, A. M., Eckart, M. E., Ewin, A. J., Finkbeiner, F. M., Figueroa-Feliciano, E., Kelley, R. L., Lee, S. J., Leutenegger, M., Porter, F. S., Sadleir, J. E., Wassell, E. J., Yoon, W. 2017; 27 (4)
  • Determination of differential orbital covalency of heme active sites by L-edge spectroscopy Baker, M., Alpert, B., Cho, H., Denison, E., Doriese, W., Fowler, J., Gaffney, K., Gard, J., Gao, B., Hilton, G., Irwin, K., Joe, Y., Kenney, C., Knight, J., Kroll, T., Lee, S., Li, D., Marks, R., Minitti, M., Morgan, K., Mori, R., Ogasawara, H., O'Neil, G., Schmidt, D., Sokaras, D., Swetz, D., Song, Y., Titus, C., Ullom, J., Weng, T., Williams, C., Yan, J., Young, B., Nordlund, D., Solomon, E. AMER CHEMICAL SOC. 2017
  • Ultra sensitive probing of the local electronic structure based on state-of-the-art Transition-Edge Sensor (TES) technology and soft x-ray spectroscopy Nordlund, D., Alpert, B., Baker, M., Cho, H., Denison, E., Doriese, W., Fowler, J., Gaffney, K., Gao, B., Gard, J., Hilton, G., Irwin, K., Joe, Y., Kenney, C., Knight, J., Kroll, T., Lee, S., Li, D., Marks, R., Minitti, M., Mori, R., Ogasawara, H., O'Neil, G., Schmidt, D., Sokaras, D., Swetz, D., Song, Y., Titus, C., Ullom, J., Weng, T., Williams, C., Young, B. AMER CHEMICAL SOC. 2017
  • Probing the local electronic structure of dilute bioinorganic active sites using ultra-sensitive soft X-ray detectors Titus, C., Alpert, B., Baker, M., Cho, H., Denison, E., Doriese, W., Fowler, J., Gaffney, K., Gao, B., Gard, J., Hilton, G., Irwin, K., Joe, Y., Kenney, C., Knight, J., Kroll, T., Lee, S., Li, D., Minitti, M., Morgan, K., Mori, R., Nordlund, D., O'Neil, G., Ogasawara, H., Reintsema, C., Schmidt, D., Sokaras, D., Song, Y., Swetz, D., Ullom, J., Weng, T., Williams, C., Young, B. AMER CHEMICAL SOC. 2017
  • Ultrasensitive probing of the local electronic structure of nitrogen doped carbon and its applications to 2D electronics, catalysis and bio-physics Lee, S., Mori, R., Alpert, B., Baker, M., Berry, J., Cho, H., Denison, E., Doriese, W., Fowler, J., Gaffney, K., Gao, B., Gard, J., Hilton, G., Irwin, K., Joe, Y., Kaya, S., Kenney, C., Knight, J., Kroll, T., Li, D., Marks, R., Minitti, M., Morgan, K., Nordlund, D., O'Neil, G., Ogasawara, H., Pianetta, P., Reintsema, C., Schiros, T., Schmidt, D., Sokaras, D., Song, Y., Swetz, D., Titus, C., Ullom, J., Weng, T., Williams, C., Wolcott, A., Young, B. AMER CHEMICAL SOC. 2017
  • XESCA: X-ray emission spectroscopy for chemical analysis Lee, S. AMER CHEMICAL SOC. 2017
  • Development of x-ray microcalorimeter imaging spectrometers for the X-ray Surveyor mission concept Bandler, S. R., Adams, J. S., Chervenak, J. A., Datesman, A. M., Eckart, M. E., Finkbeiner, F. M., Kelley, R. L., Kilbourne, C. A., Betancourt-Martineza, G., Miniussi, A. R., Porter, F. S., Sadleir, J. E., Sakai, K., Smith, S. J., Stevenson, T. R., Wakeham, N. A., Wassell, E. J., Yoon, W., Becker, D., Bennett, D., Doriese, W. B., Fowler, J. W., Gard, J. D., Hilton, G. C., Mates, B., Morgan, K. M., Reintsema, C. D., Swetz, D., Ullom, J. N., Chaudhuri, S., Irwin, K. D., Lee, S., Vikhlinin, A., DenHerder, J. W., Takahashi, T., Bautz, M. SPIE-INT SOC OPTICAL ENGINEERING. 2016

    View details for DOI 10.1117/12.2232156

    View details for Web of Science ID 000387731500017