Xueli (Sherry) Zheng is a Physical Science Research Scientist in the Department of Materials Science and Engineering at Stanford University. Dr. Zheng did her postdoctoral research at Stanford University, working with Prof. Yi Cui and Prof. Leora Dresselhaus-Marais in the Department of Materials Science and Engineering. Her research focuses on 1) decarbonizing steelmaking using sustainable hydrogen; 2) developing, understanding, and integrating materials and devices for electrocatalysis and battery technologies; 3) constructing a toolbox of innovative techniques (synchrotron X-ray spectroscopy and imaging) to establish the fundamental understanding of sustainable manufacturing, electrocatalysis, and battery technologies.

Education & Certifications

  • Postdoc, Stanford University, Materials Science and Engineering (2017)


  • Bo Zhang, Xueli Zheng, Oleksandr VOZNYY, Sjoerd HOOGLAND, Jixian XU, Min Liu, Cao-Thang DINH, Edward Sargent. "United States Patent US20170218528A1 Homogeneously dispersed multimetal oxy-hydroxide catalysts"

All Publications

  • Solvation-property relationship of lithium-sulphur battery electrolytes. Nature communications Kim, S. C., Gao, X., Liao, S., Su, H., Chen, Y., Zhang, W., Greenburg, L. C., Pan, J., Zheng, X., Ye, Y., Kim, M. S., Sayavong, P., Brest, A., Qin, J., Bao, Z., Cui, Y. 2024; 15 (1): 1268


    The Li-S battery is a promising next-generation battery chemistry that offers high energy density and low cost. The Li-S battery has a unique chemistry with intermediate sulphur species readily solvated in electrolytes, and understanding their implications is important from both practical and fundamental perspectives. In this study, we utilise the solvation free energy of electrolytes as a metric to formulate solvation-property relationships in various electrolytes and investigate their impact on the solvated lithium polysulphides. We find that solvation free energy influences Li-S battery voltage profile, lithium polysulphide solubility, Li-S battery cyclability and the Li metal anode; weaker solvation leads to lower 1st plateau voltage, higher 2nd plateau voltage, lower lithium polysulphide solubility, and superior cyclability of Li-S full cells and Li metal anodes. We believe that relationships delineated in this study can guide the design of high-performance electrolytes for Li-S batteries.

    View details for DOI 10.1038/s41467-023-44527-x

    View details for PubMedID 38341443

  • Correlating chemistry and mass transport in sustainable iron production. Proceedings of the National Academy of Sciences of the United States of America Zheng, X., Paul, S., Moghimi, L., Wang, Y., Vilá, R. A., Zhang, F., Gao, X., Deng, J., Jiang, Y., Xiao, X., Wu, C., Greenburg, L. C., Yang, Y., Cui, Y., Vailionis, A., Kuzmenko, I., Llavsky, J., Yin, Y., Cui, Y., Dresselhaus-Marais, L. 2023; 120 (43): e2305097120


    Steelmaking contributes 8% to the total CO2 emissions globally, primarily due to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable performance because the dominant gas-solid reduction mechanism is set by the defects and pores inside the mm- to nm-sized oxide particles that change significantly as the reaction progresses. While these governing dynamics are essential to establish continuous flow of iron and its ores through reactors, the direct link between agglomeration and chemistry is still contested due to missing measurements. In this work, we directly measure the connection between chemistry and agglomeration in the smallest iron oxides relevant to magnetite ores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we resolve the formation and consumption of wüstite (Fe1-xO)-the step most commonly attributed to whiskering. Using X-ray diffraction, we resolve crystallographic anisotropy in the rate of the initial reaction. Complementary imaging demonstrated how the particles self-assemble, subsequently react, and grow into elongated "whisker" structures. Our insights into how morphologically uniform iron oxide particles react and agglomerate in H2 reduction enable future size-dependent models to effectively describe the multiscale aspects of iron ore reduction.

    View details for DOI 10.1073/pnas.2305097120

    View details for PubMedID 37847734

  • Electrolytes with moderate lithium polysulfide solubility for high-performance long-calendar-life lithium-sulfur batteries. Proceedings of the National Academy of Sciences of the United States of America Gao, X., Yu, Z., Wang, J., Zheng, X., Ye, Y., Gong, H., Xiao, X., Yang, Y., Chen, Y., Bone, S. E., Greenburg, L. C., Zhang, P., Su, H., Affeld, J., Bao, Z., Cui, Y. 2023; 120 (31): e2301260120


    Lithium-sulfur (Li-S) batteries with high energy density and low cost are promising for next-generation energy storage. However, their cycling stability is plagued by the high solubility of lithium polysulfide (LiPS) intermediates, causing fast capacity decay and severe self-discharge. Exploring electrolytes with low LiPS solubility has shown promising results toward addressing these challenges. However, here, we report that electrolytes with moderate LiPS solubility are more effective for simultaneously limiting the shuttling effect and achieving good Li-S reaction kinetics. We explored a range of solubility from 37 to 1,100 mM (based on S atom, [S]) and found that a moderate solubility from 50 to 200 mM [S] performed the best. Using a series of electrolyte solvents with various degrees of fluorination, we formulated the Single-Solvent, Single-Salt, Standard Salt concentration with Moderate LiPSs solubility Electrolytes (termed S6MILE) for Li-S batteries. Among the designed electrolytes, Li-S cells using fluorinated-1,2-diethoxyethane S6MILE (F4DEE-S6MILE) showed the highest capacity of 1,160 mAh g-1 at 0.05 C at room temperature. At 60 °C, fluorinated-1,4-dimethoxybutane S6MILE (F4DMB-S6MILE) gave the highest capacity of 1,526 mAh g-1 at 0.05 C and an average CE of 99.89% for 150 cycles at 0.2 C under lean electrolyte conditions. This is a fivefold increase in cycle life compared with other conventional ether-based electrolytes. Moreover, we observed a long calendar aging life, with a capacity increase/recovery of 4.3% after resting for 30 d using F4DMB-S6MILE. Furthermore, the correlation between LiPS solubility, degree of fluorination of the electrolyte solvent, and battery performance was systematically investigated.

    View details for DOI 10.1073/pnas.2301260120

    View details for PubMedID 37487097

  • All-Solid-State Lithium-Sulfur Batteries Enhanced by Redox Mediators. Journal of the American Chemical Society Gao, X., Zheng, X., Tsao, Y., Zhang, P., Xiao, X., Ye, Y., Li, J., Yang, Y., Xu, R., Bao, Z., Cui, Y. 2021


    Redox mediators (RMs) play a vital role in some liquid electrolyte-based electrochemical energy storage systems. However, the concept of redox mediator in solid-state batteries remains unexplored. Here, we selected a group of RM candidates and investigated their behaviors and roles in all-solid-state lithium-sulfur batteries (ASSLSBs). The soluble-type quinone-based RM (AQT) shows the most favorable redox potential and the best redox reversibility that functions well for lithium sulfide (Li2S) oxidation in solid polymer electrolytes. Accordingly, Li2S cathodes with AQT RMs present a significantly reduced energy barrier (average oxidation potential of 2.4 V) during initial charging at 0.1 C at 60 °C and the following discharge capacity of 1133 mAh gs-1. Using operando sulfur K-edge X-ray absorption spectroscopy, we directly tracked the sulfur speciation in ASSLSBs and proved that the solid-polysulfide-solid reaction of Li2S cathodes with RMs facilitated Li2S oxidation. In contrast, for bare Li2S cathodes, the solid-solid Li2S-sulfur direct conversion in the first charge cycle results in a high energy barrier for activation (charge to 4 V) and low sulfur utilization. The Li2S@AQT cell demonstrates superior cycling stability (average Coulombic efficiency 98.9% for 150 cycles) and rate capability owing to the effective AQT-enhanced Li-S reaction kinetics. This work reveals the evolution of sulfur species in ASSLSBs and realizes the fast Li-S reaction kinetics by designing an effective sulfur speciation pathway.

    View details for DOI 10.1021/jacs.1c07754

    View details for PubMedID 34677957

  • Defect-mediated ferromagnetism in correlated two-dimensional transition metal phosphorus trisulfides. Science advances Wang, F., Mathur, N., Janes, A. N., Sheng, H., He, P., Zheng, X., Yu, P., DeRuiter, A. J., Schmidt, J. R., He, J., Jin, S. 2021; 7 (43): eabj4086


    [Figure: see text].

    View details for DOI 10.1126/sciadv.abj4086

    View details for PubMedID 34678059

  • Origin of enhanced water oxidation activity in an iridium single atom anchored on NiFe oxyhydroxide catalyst PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zheng, X., Tang, J., Gallo, A., Torres, J., Yu, X., Athanitis, C. J., Been, E., Ercius, P., Mao, H., Fakra, S. C., Song, C., Davis, R. C., Reimer, J. A., Vinson, J., Bajdich, M., Cui, Y. 2021; 118 (36)
  • Concentrated dual-cation electrolyte strategy for aqueous zinc-ion batteries ENERGY & ENVIRONMENTAL SCIENCE Zhu, Y., Yin, J., Zheng, X., Emwas, A., Lei, Y., Mohammed, O. F., Cui, Y., Alshareef, H. N. 2021

    View details for DOI 10.1039/d1ee01472b

    View details for Web of Science ID 000677442500001

  • Large Scale Synthesis of Manganese Oxide/Reduced Graphene Oxide Composites as Anode Materials for Long Cycle Lithium Ion Batteries ACS APPLIED ENERGY MATERIALS Meng, Y., Liu, Y., He, J., Sun, X., Palmieri, A., Gu, Y., Zheng, X., Dang, Y., Huang, X., Mustain, W., Suib, S. L. 2021; 4 (6): 5424-5433
  • Organic wastewater treatment by a single-atom catalyst and electrolytically produced H2O2. Nature sustainability Xu, J., Zheng, X., Feng, Z., Lu, Z., Zhang, Z., Huang, W., Li, Y., Vuckovic, D., Li, Y., Dai, S., Chen, G., Wang, K., Wang, H., Chen, J. K., Mitch, W., Cui, Y. 2021; 4: 233-241


    The presence of organic contaminants in wastewater poses considerable risks to the health of both humans and ecosystems. Although advanced oxidation processes that rely on highly reactive radicals to destroy organic contaminants are appealing treatment options, substantial energy and chemical inputs limit their practical applications. Here we demonstrate that Cu single atoms incorporated in graphitic carbon nitride can catalytically activate H2O2 to generate hydroxyl radicals at pH 7.0 without energy input, and show robust stability within a filtration device. We further design an electrolysis reactor for the on-site generation of H2O2 from air, water and renewable energy. Coupling the single-atom catalytic filter and the H2O2 electrolytic generator in tandem delivers a wastewater treatment system. These findings provide a promising path toward reducing the energy and chemical demands of advanced oxidation processes, as well as enabling their implementation in remote areas and isolated communities.

    View details for DOI 10.1038/s41893-020-00635-w

    View details for PubMedID 34355066

    View details for PubMedCentralID PMC8330436

  • Organic wastewater treatment by a single-atom catalyst and electrolytically produced H2O2 NATURE SUSTAINABILITY Xu, J., Zheng, X., Feng, Z., Lu, Z., Zhang, Z., Huang, W., Li, Y., Vuckovic, D., Li, Y., Dai, S., Chen, G., Wang, K., Wang, H., Chen, J. K., Mitch, W., Cui, Y. 2020
  • Incorporating the nanoscale encapsulation concept from liquid electrolytes into solid-state lithium-sulfur batteries. Nano letters Gao, X., Zheng, X., Wang, J., Zhang, Z., Xiao, X., Wan, J., Ye, Y., Chou, L., Lee, H. K., Wang, J., Vila, R. A., Yang, Y., Zhang, P., Wang, L., Cui, Y. 2020


    Lithium-sulfur (Li-S) batteries are attractive due to their high specific energy and low-cost prospect. Most studies in the past decade are based on these batteries with liquid electrolytes, where many exciting material/structural designs are realized at the nanoscale to address problems of Li-S chemistry. Recently, there is a new promising direction to develop Li-S batteries with solid polymer electrolytes, although it is unclear whether the concepts from liquid electrolytes are applicable in the solid state to improve battery performance. Here we demonstrate that the nanoscale encapsulation concept based on Li2S-TiS2 core-shell particles, originally developed in liquid electrolytes, is very effective in solid polymer electrolytes. Using in situ optical cell measurement and sulfur K-edge X-ray absorption near edge spectroscopy, we find that polysulfides form and are well trapped inside individual particles by the nanoscale TiS2 encapsulation. This TiS2 encapsulation layer also functions to catalyze the oxidation reaction of Li2S to sulfur, even in solid-state electrolytes, proved by both experiments and density functional theory calculations. A high cell-level specific energy of 427 W∙h∙kg-1 at 60 °C (including the mass of the anode, cathode, and solid-state electrolyte, but excluding the current collector and packaging) is achieved by integrating TiS2 encapsulated Li2S cathode with ultrathin polyethylene oxide-based solid polymer electrolyte (10~20 m) and lithium metal anode. The solid-state cells show excellent stability over 150 charge/discharge cycles at 0.8 C at 80 °C. This study points to the fruitful direction of borrowing concepts from liquid electrolytes into solid-state Li-S batteries.

    View details for DOI 10.1021/acs.nanolett.0c02033

    View details for PubMedID 32515973

  • Synergistic enhancement of electrocatalytic CO2 reduction to C2 oxygenates at nitrogen-doped nanodiamonds/Cu interface. Nature nanotechnology Wang, H., Tzeng, Y., Ji, Y., Li, Y., Li, J., Zheng, X., Yang, A., Liu, Y., Gong, Y., Cai, L., Li, Y., Zhang, X., Chen, W., Liu, B., Lu, H., Melosh, N. A., Shen, Z., Chan, K., Tan, T., Chu, S., Cui, Y. 2020


    To date, effective control over the electrochemical reduction of CO2 to multicarbon products (C≥2) has been very challenging. Here, we report a design principle for the creation of a selective yet robust catalytic interface for heterogeneous electrocatalysts in the reduction of CO2 to C2 oxygenates, demonstrated by rational tuning of an assembly of nitrogen-doped nanodiamonds and copper nanoparticles. The catalyst exhibits a Faradaic efficiency of ~63% towards C2 oxygenates at applied potentials of only -0.5V versus reversible hydrogen electrode. Moreover, this catalyst shows an unprecedented persistent catalytic performance up to 120h, with steady current and only 19% activity decay. Density functional theory calculations show that CO binding is strengthened at the copper/nanodiamond interface, suppressing CO desorption and promoting C2 production by lowering the apparent barrier for CO dimerization. The inherent compositional and electronic tunability of the catalyst assembly offers an unrivalled degree of control over the catalytic interface, and thereby the reaction energetics and kinetics.

    View details for DOI 10.1038/s41565-019-0603-y

    View details for PubMedID 31907442

  • Active Sulfur Sites in Semimetallic Titanium Disulfide Enable CO2 Electroreduction ACS CATALYSIS Allabour, A., Coskun, H., Zheng, X., Kibria, M., Strobel, M., Hild, S., Kehrer, M., Stifter, D., Sargent, E. H., Stadler, P. 2020; 10 (1): 66–72
  • Electrochemical generation of liquid and solid sulfur on two-dimensional layered materials with distinct areal capacities. Nature nanotechnology Yang, A. n., Zhou, G. n., Kong, X. n., Vilá, R. A., Pei, A. n., Wu, Y. n., Yu, X. n., Zheng, X. n., Wu, C. L., Liu, B. n., Chen, H. n., Xu, Y. n., Chen, D. n., Li, Y. n., Fakra, S. n., Hwang, H. Y., Qin, J. n., Chu, S. n., Cui, Y. n. 2020


    It has recently been shown that sulfur, a solid material in its elementary form S8, can stay in a supercooled state as liquid sulfur in an electrochemical cell. We establish that this newly discovered state could have implications for lithium-sulfur batteries. Here, through in situ studies of electrochemical sulfur generation, we show that liquid (supercooled) and solid elementary sulfur possess very different areal capacities over the same charging period. To control the physical state of sulfur, we studied its growth on two-dimensional layered materials. We found that on the basal plane, only liquid sulfur accumulates; by contrast, at the edge sites, liquid sulfur accumulates if the thickness of the two-dimensional material is small, whereas solid sulfur nucleates if the thickness is large (tens of nanometres). Correlating the sulfur states with their respective areal capacities, as well as controlling the growth of sulfur on two-dimensional materials, could provide insights for the design of future lithium-sulfur batteries.

    View details for DOI 10.1038/s41565-019-0624-6

    View details for PubMedID 31988508

  • Electrochemical generation of liquid and solid sulfur on two-dimensional layered materials with distinct areal capacities Nature Nanotechnology Yang, A., Zhou, G., et al 2020
  • Highly active oxygen evolution integrated with efficient CO2 to CO electroreduction. Proceedings of the National Academy of Sciences of the United States of America Meng, Y., Zhang, X., Hung, W., He, J., Tsai, Y., Kuang, Y., Kenney, M. J., Shyue, J., Liu, Y., Stone, K. H., Zheng, X., Suib, S. L., Lin, M., Liang, Y., Dai, H. 2019


    Electrochemical reduction of CO2 to useful chemicals has been actively pursued for closing the carbon cycle and preventing further deterioration of the environment/climate. Since CO2 reduction reaction (CO2RR) at a cathode is always paired with the oxygen evolution reaction (OER) at an anode, the overall efficiency of electrical energy to chemical fuel conversion must consider the large energy barrier and sluggish kinetics of OER, especially in widely used electrolytes, such as the pH-neutral CO2-saturated 0.5 M KHCO3 OER in such electrolytes mostly relies on noble metal (Ir- and Ru-based) electrocatalysts in the anode. Here, we discover that by anodizing a metallic Ni-Fe composite foam under a harsh condition (in a low-concentration 0.1 M KHCO3 solution at 85 °C under a high-current 250 mA/cm2), OER on the NiFe foam is accompanied by anodic etching, and the surface layer evolves into a nickel-iron hydroxide carbonate (NiFe-HC) material composed of porous, poorly crystalline flakes of flower-like NiFe layer-double hydroxide (LDH) intercalated with carbonate anions. The resulting NiFe-HC electrode in CO2-saturated 0.5 M KHCO3 exhibited OER activity superior to IrO2, with an overpotential of 450 and 590 mV to reach 10 and 250 mA/cm2, respectively, and high stability for >120 h without decay. We paired NiFe-HC with a CO2RR catalyst of cobalt phthalocyanine/carbon nanotube (CoPc/CNT) in a CO2 electrolyzer, achieving selective cathodic conversion of CO2 to CO with >97% Faradaic efficiency and simultaneous anodic water oxidation to O2 The device showed a low cell voltage of 2.13 V and high electricity-to-chemical fuel efficiency of 59% at a current density of 10 mA/cm2.

    View details for DOI 10.1073/pnas.1915319116

    View details for PubMedID 31723041

  • Surface-engineered mesoporous silicon microparticles as high-Coulombic-efficiency anodes for lithium-ion batteries NANO ENERGY Wang, J., Liao, L., Lee, H., Shi, F., Huang, W., Zhao, J., Pei, A., Tang, J., Zheng, X., Chen, W., Cui, Y. 2019; 61: 404–10
  • Atomically engineering activation sites onto metallic 1T-MoS2 catalysts for enhanced electrochemical hydrogen evolution NATURE COMMUNICATIONS Huang, Y., Sun, Y., Zheng, X., Aoki, T., Pattengale, B., Huang, J., He, X., Bian, W., Younan, S., Williams, N., Hu, J., Ge, J., Pu, N., Yan, X., Pan, X., Zhang, L., Wei, Y., Gu, J. 2019; 10
  • Atomically engineering activation sites onto metallic 1T-MoS2 catalysts for enhanced electrochemical hydrogen evolution. Nature communications Huang, Y., Sun, Y., Zheng, X., Aoki, T., Pattengale, B., Huang, J., He, X., Bian, W., Younan, S., Williams, N., Hu, J., Ge, J., Pu, N., Yan, X., Pan, X., Zhang, L., Wei, Y., Gu, J. 2019; 10 (1): 982


    Engineering catalytic sites at the atomic level provides an opportunity to understand the catalyst's active sites, which is vital to the development of improved catalysts. Here we show a reliable and tunable polyoxometalate template-based synthetic strategy to atomically engineer metal doping sites onto metallic 1T-MoS2, using Anderson-type polyoxometalates as precursors. Benefiting from engineering nickel and oxygen atoms, the optimized electrocatalyst shows great enhancement in the hydrogen evolution reaction with a positive onset potential of ~0V and a low overpotential of -46mV in alkaline electrolyte, comparable to platinum-based catalysts. First-principles calculations reveal co-doping nickel and oxygen into 1T-MoS2 assists the process of water dissociation and hydrogen generation from their intermediate states. This research will expand on the ability to improve the activities of various catalysts by precisely engineering atomic activation sites to achieve significant electronic modulations and improve atomic utilization efficiencies.

    View details for PubMedID 30816110

  • Breathing-Mimicking Electrocatalysis for Oxygen Evolution and Reduction JOULE Li, J., Zhu, Y., Chen, W., Lu, Z., Xu, J., Pei, A., Peng, Y., Zheng, X., Zhang, Z., Chu, S., Cui, Y. 2019; 3 (2): 557–69
  • Reversible and selective ion intercalation through the top surface of few-layer MoS2. Nature communications Zhang, J., Yang, A., Wu, X., van de Groep, J., Tang, P., Li, S., Liu, B., Shi, F., Wan, J., Li, Q., Sun, Y., Lu, Z., Zheng, X., Zhou, G., Wu, C., Zhang, S., Brongersma, M. L., Li, J., Cui, Y. 2018; 9 (1): 5289


    Electrochemical intercalation of ions into the van der Waals gap of two-dimensional (2D) layered materials is a promising low-temperature synthesis strategy to tune their physical and chemical properties. It is widely believed that ions prefer intercalation into the van der Waals gap through the edges of the 2D flake, which generally causes wrinkling and distortion. Here we demonstrate that the ions can also intercalate through the top surface of few-layer MoS2 and this type of intercalation is more reversible and stable compared to the intercalation through the edges. Density functional theory calculations show that this intercalation is enabled by the existence of natural defects in exfoliated MoS2 flakes. Furthermore, we reveal that sealed-edge MoS2 allows intercalation of small alkali metal ions (e.g., Li+ and Na+) and rejects large ions (e.g., K+). These findings imply potential applications in developing functional 2D-material-based devices with high tunability and ion selectivity.

    View details for PubMedID 30538249

  • Reversible and selective ion intercalation through the top surface of few-layer MoS2 NATURE COMMUNICATIONS Zhang, J., Yang, A., Wu, X., van de Groep, J., Tang, P., Li, S., Liu, B., Shi, F., Wan, J., Li, Q., Sun, Y., Lu, Z., Zheng, X., Zhou, G., Wu, C., Zhang, S., Brongersma, M. L., Li, J., Cui, Y. 2018; 9
  • Atomic-level structure engineering of metal oxides for high-rate oxygen intercalation pseudocapacitance. Science advances Ling, T., Da, P., Zheng, X., Ge, B., Hu, Z., Wu, M., Du, X., Hu, W., Jaroniec, M., Qiao, S. 2018; 4 (10): eaau6261


    Atomic-level structure engineering can substantially change the chemical and physical properties of materials. However, the effects of structure engineering on the capacitive properties of electrode materials at the atomic scale are poorly understood. Fast transport of ions and electrons to all active sites of electrode materials remains a grand challenge. Here, we report the radical modification of the pseudocapacitive properties of an oxide material, Zn x Co1-x O, via atomic-level structure engineering, which changes its dominant charge storage mechanism from surface redox reactions to ion intercalation into bulk material. Fast ion and electron transports are simultaneously achieved in this mixed oxide, increasing its capacity almost to the theoretical limit. The resultant Zn x Co1-x O exhibits high-rate performance with capacitance up to 450 F g-1 at a scan rate of 1 V s-1, competing with the state-of-the-art transition metal carbides. A symmetric device assembled with Zn x Co1-x O achieves an energy density of 67.3 watt-hour kg-1 at a power density of 1.67 kW kg-1, which is the highest value ever reported for symmetric pseudocapacitors. Our finding suggests that the rational design of electrode materials at the atomic scale opens a new opportunity for achieving high power/energy density electrode materials for advanced energy storage devices.

    View details for PubMedID 30345366

  • Highly Emissive Green Perovskite Nanocrystals in a Solid State Crystalline Matrix. Advanced materials Quan, L. N., Quintero-Bermudez, R., Voznyy, O., Walters, G., Jain, A., Fan, J. Z., Zheng, X., Yang, Z., Sargent, E. H. 2017; 29 (21)


    Perovskite nanocrystals (NCs) have attracted attention due to their high photoluminescence quantum yield (PLQY) in solution; however, maintaining high emission efficiency in the solid state remains a challenge. This study presents a solution-phase synthesis of efficient green-emitting perovskite NCs (CsPbBr3 ) embedded in robust and air-stable rhombic prism hexabromide (Cs4 PbBr6 ) microcrystals, reaching a PLQY of 90%. Theoretical modeling and experimental characterization suggest that lattice matching between the NCs and the matrix contribute to improved passivation, while spatial confinement enhances the radiative rate of the NCs. In addition, dispersing the NCs in a matrix prevents agglomeration, which explains their high PLQY.

    View details for DOI 10.1002/adma.201605945

    View details for PubMedID 28370565

  • Enhanced Solar-to-Hydrogen Generation with Broadband Epsilon-Near-Zero Nanostructured Photocatalysts. Advanced materials Tian, Y., García de Arquer, F. P., Dinh, C., Favraud, G., Bonifazi, M., Li, J., Liu, M., Zhang, X., Zheng, X., Kibria, M. G., Hoogland, S., Sinton, D., Sargent, E. H., Fratalocchi, A. 2017


    The direct conversion of solar energy into fuels or feedstock is an attractive approach to address increasing demand of renewable energy sources. Photocatalytic systems relying on the direct photoexcitation of metals have been explored to this end, a strategy that exploits the decay of plasmonic resonances into hot carriers. An efficient hot carrier generation and collection requires, ideally, their generation to be enclosed within few tens of nanometers at the metal interface, but it is challenging to achieve this across the broadband solar spectrum. Here the authors demonstrate a new photocatalyst for hydrogen evolution based on metal epsilon-near-zero metamaterials. The authors have designed these to achieve broadband strong light confinement at the metal interface across the entire solar spectrum. Using electron energy loss spectroscopy, the authors prove that hot carriers are generated in a broadband fashion within 10 nm in this system. The resulting photocatalyst achieves a hydrogen production rate of 9.5 µmol h-1  cm-2 that exceeds, by a factor of 3.2, that of the best previously reported plasmonic-based photocatalysts for the dissociation of H2 with 50 h stable operation.

    View details for DOI 10.1002/adma.201701165

    View details for PubMedID 28481018

  • Modest Oxygen-Defective Amorphous Manganese-Based Nanoparticle Mullite with Superior Overall Electrocatalytic Performance for Oxygen Reduction Reaction SMALL Dong, C., Liu, Z., Liu, J., Wang, W., Cui, L., Luo, R., Guo, H., Zheng, X., Qiao, S., Du, X., Yang, J. 2017; 13 (16)


    Manganese-based oxides have exhibited high promise as noncoinage alternatives to Pt/C for catalyzing oxygen reduction reaction (ORR) in basic solution and a mix of Mn3+/4+ valence is believed to be vital in achieving optimum ORR performance. Here, it is proposed that, distinct from the most studied perovskites and spinels, Mn-based mullites with equivalent molar ratio of Mn3+ and Mn4+ provide a unique platform to maximize the role of Mn valence in facile ORR kinetics by introducing modest content of oxygen deficiency, which is also beneficial to enhanced catalytic activity. Accordingly, amorphous mullite SmMn2 O5-δ nanoparticles with finely tuned concentration of oxygen vacancies are synthesized via a versatile top-down approach and the modest oxygen-defective sample with an Mn3+ /Mn4+ ratio of 1.78, i.e., Mn valence of 3.36 gives rise to a superior overall ORR activity among the highest reported for the family of Mn-based oxides, comparable to that of Pt/C. Altogether, this study opens up great opportunities for mullite-based catalysts to be a cost-effective alternative to Pt/C in diverse electrochemical energy storage and conversion systems.

    View details for DOI 10.1002/smll.201603903

    View details for Web of Science ID 000399455900012

    View details for PubMedID 28195444

  • Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption Nature Chemistry Zheng, X., Zhang, B., De Luna, P., Liang, Y., Comin, R., Du, X., Sargent, E. 2017

    View details for DOI 10.1038/NCHEM.2886

  • Enhanced electrocatalytic CO2 reduction via field-induced reagent concentration NATURE Liu, M., Pang, Y., Zhang, B., De Luna, P., Voznyy, O., Xu, J., Zheng, X., Dinh, C. T., Fan, F., Cao, C., de Arquer, F. P., Safaei, T. S., Mepham, A., Klinkova, A., Kumacheva, E., Filleter, T., Sinton, D., Kelley, S. O., Sargent, E. H. 2016; 537 (7620): 382-?
  • Engineering surface atomic structure of single-crystal cobalt (II) oxide nanorods for superior electrocatalysis NATURE COMMUNICATIONS Ling, T., Yan, D., Jiao, Y., Wang, H., Zheng, Y., Zheng, X., Mao, J., Du, X., Hu, Z., Jaroniec, M., Qiao, S. 2016; 7


    Engineering the surface structure at the atomic level can be used to precisely and effectively manipulate the reactivity and durability of catalysts. Here we report tuning of the atomic structure of one-dimensional single-crystal cobalt (II) oxide (CoO) nanorods by creating oxygen vacancies on pyramidal nanofacets. These CoO nanorods exhibit superior catalytic activity and durability towards oxygen reduction/evolution reactions. The combined experimental studies, microscopic and spectroscopic characterization, and density functional theory calculations reveal that the origins of the electrochemical activity of single-crystal CoO nanorods are in the oxygen vacancies that can be readily created on the oxygen-terminated {111} nanofacets, which favourably affect the electronic structure of CoO, assuring a rapid charge transfer and optimal adsorption energies for intermediates of oxygen reduction/evolution reactions. These results show that the surface atomic structure engineering is important for the fabrication of efficient and durable electrocatalysts.

    View details for DOI 10.1038/ncomms12876

    View details for Web of Science ID 000385384100010

    View details for PubMedID 27650485

    View details for PubMedCentralID PMC5035995

  • Strongly Coupled Nafion Molecules and Ordered Porous CdS Networks for Enhanced Visible-Light Photoelectrochemical Hydrogen Evolution ADVANCED MATERIALS Zheng, X., Song, J., Ling, T., Hu, Z. P., Yin, P., Davey, K., Du, X., Qiao, S. 2016; 28 (24): 4935-4942


    Strongly coupled Nafion molecules and ordered porous CdS networks are fabricated for visible-light photoelectrochemical (PEC) hydrogen evolution. The Nafion layer coating shifts the band position of CdS upward and accelerates charge transfer in the photoelectrode/electrolyte interface. It is highly expected that the strong coupling effect between organic and inorganic materials will provide new routes to advance PEC water splitting.

    View details for DOI 10.1002/adma.201600437

    View details for Web of Science ID 000378939200020

    View details for PubMedID 27038367

  • Homogeneously dispersed multimetal oxygen-evolving catalysts. Science Zhang, B., Zheng, X., Voznyy, O., Comin, R., Bajdich, M., García-Melchor, M., Han, L., Xu, J., Liu, M., Zheng, L., García de Arquer, F. P., Dinh, C. T., Fan, F., Yuan, M., Yassitepe, E., Chen, N., Regier, T., Liu, P., Li, Y., De Luna, P., Janmohamed, A., Xin, H. L., Yang, H., Vojvodic, A., Sargent, E. H. 2016; 352 (6283): 333-337


    Earth-abundant first-row (3d) transition metal-based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials substantially above thermodynamic requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxyhydroxides materials with an atomically homogeneous metal distribution. These gelled FeCoW oxyhydroxides exhibit the lowest overpotential (191 millivolts) reported at 10 milliamperes per square centimeter in alkaline electrolyte. The catalyst shows no evidence of degradation after more than 500 hours of operation. X-ray absorption and computational studies reveal a synergistic interplay between tungsten, iron, and cobalt in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER.

    View details for DOI 10.1126/science.aaf1525

    View details for PubMedID 27013427