Jinheng Xu

All Publications

• Structural and Electronic Properties of Anionic (ThO2)n- (n = 2-4) Clusters. Inorganic chemistry Yuan, M., Tufekci, B. A., Xu, J., Foreman, K., Heaven, M. C., Batista, E. R., Bowen, K. H., Yang, P. 2025; 64 (10): 4953-4963

  Abstract

  Thorium dioxide nanomaterials have attracted broad interest due to their catalytic properties and their possible use as fuel in next generation nuclear reactors. Investigation of their chemical and physical properties benefits from exploration of the electronic structure of small cluster units. A joint computational and experimental study is reported herein of the geometric and electronic structure of the neutral and anionic thorium dioxide clusters (ThO2)n0/-, n = 2, 3, 4. Differences were found in the identity of the global minimum structure and the distribution of structural isomers between the neutral clusters and their anionic counterparts at each size that can be traced to the nature of the highest occupied molecular orbital (HOMO). The computed vertical detachment energy (VDE) value of each cluster was in excellent agreement with the first peak of the experimental anion photoelectron spectroscopy (aPES) spectra. This spectral feature was identified as corresponding to electron ionizations from the HOMO of the global minimum structure in the (ThO2)n- (n = 2, 3, 4) clusters. To explore the origin of spectral features in the measured spectra of (ThO2)n- (n = 2, 3, 4) beyond the vertical detachment energy (VDE) peaks, a quantitative evaluation of the existing isomers was performed based on their Boltzmann distribution ratios. These fine spectral details were partially attributed to the contribution of structural isomers beyond the global minimum.

  View details for DOI 10.1021/acs.inorgchem.4c04954

  View details for PubMedID 40030040

• Spraying of water microdroplets forms luminescence and causes chemical reactions in surrounding gas. Science advances Meng, Y., Xia, Y., Xu, J., Zare, R. N. 2025; 11 (11): eadt8979

  Abstract

  When neutral water is sprayed, oppositely charged microdroplets are formed. The close approach of oppositely charged microdroplets causes an electrical discharge and leads to luminescent emission. The light emission happens without any external voltage applied, and the electrical discharge is sufficiently energetic to excite, dissociate, or ionize surrounding neutral gas molecules. Thus, sprayed water microdroplets cause chemical reactions to occur. Similar findings to the Urey-Miller experiment were observed by spraying room temperature water microdroplets into a gas mixture containing nitrogen, methane, carbon dioxide, and ammonia, which leads to the synthesis of organic molecules containing carbon-nitrogen (C─N) bonds. These observations provide another explanation for unique reactivity at the gas-water interface, as well as a possible mechanism for making the building blocks of life on early Earth.

  View details for DOI 10.1126/sciadv.adt8979

  View details for PubMedID 40085708

• Methane Bubbled Through Seawater Can be Converted to Methanol With High Efficiency. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Song, X., Basheer, C., Xu, J., Adam, M. M., Zare, R. N. 2025: e2412246

  Abstract

  Partial oxidation of methane (POM) is achieved by forming air-methane microbubbles in saltwater to which an alternating electric field is applied using a copper oxide foam electrode. The solubility of methane is increased by putting it in contact with water containing dissolved KCl or NaCl (3%). Being fully dispersed as microbubbles (20-40 µm in diameter), methane reacts more fully with hydroxyl radicals (OH·) at the gas-water interface. The alternating voltage (100 mV) generates two synergistic POM processes dominated by Cl- → Cl· + e- and O2 + e- → O2 -• under positive and negative potentials, respectively. By tuning the frequency and amplitude, the extent and path of the POM process can be precisely controlled so that more than 90% methanol is selectively formed compared to the two byproducts, dichloromethane, and acetic acid. The methane to methanol conversion yield is estimated to be 57% at a rate of approximately 887 µM h-1. This method appears to have potential for removing methane from air using seawater or for converting higher-concentration methane sources into value-added methanol.

  View details for DOI 10.1002/advs.202412246

  View details for PubMedID 39835457

• Activation of H2O by ThO2- Experimental and Computational Studies. The journal of physical chemistry. A Tufekci, B. A., Chiba, T., Xu, J., Cheng, L., Bowen, K. H. 2025; 129 (1): 76-81

  Abstract

  A synergetic study that utilized anion photoelectron spectroscopy and high-level ab initio calculations has explored the activation of H2O molecules by ThO2- molecular anions. Both experiment and theory found conclusive evidence for said activation. In the experiments, this appeared as a tell-tale directional shift in the spectral profile of the anionic complex that ruled out physisorption, i.e., ThO2-(H2O), and implied chemisorption. In the computations, good agreement was found between the calculated and measured vertical detachment energies, and the atomic connectivity (the structure) of the resulting anionic complex was found to be [OTh(OH)2]-.

  View details for DOI 10.1021/acs.jpca.4c06238

  View details for PubMedID 39780706

• Onsite ammonia synthesis from water vapor and nitrogen in the air. Science advances Song, X., Basheer, C., Xu, J., Zare, R. N. 2024; 10 (50): eads4443

  Abstract

  An innovative method for onsite ammonia synthesis under ambient conditions has been developed using a catalyst mesh composed of magnetite (Fe3O4) and Nafion polymer. We pass air through the catalyst, which condenses microdroplets from atmospheric water vapor and uses nitrogen from the air, resulting in ammonia concentrations ranging from 25 to 120 μM in 1 hour, depending on local relative humidity. Operated at room temperature and atmospheric pressure, this technique eliminates the need for additional electricity or radiation, thereby substantially reducing carbon dioxide emissions compared to the traditional Haber-Bosch process. In laboratory experiments, we further optimized the reaction conditions and scaled up the process. After 2 hours of spraying, the ammonia concentration increased to 270.2 ± 25.1 μM. In addition, we present a portable device designed for onsite ammonia production which consistently produces an ammonia concentration that is adequate for some agricultural irrigation purposes.

  View details for DOI 10.1126/sciadv.ads4443

  View details for PubMedID 39671479

• Methane C(sp3)-H bond activation by water microbubbles. Chemical science Li, J., Xu, J., Song, Q., Zhang, X., Xia, Y., Zare, R. N. 2024

  Abstract

  Microbubble-induced oxidation offers an effective approach for activating the C(sp3)-H bond of methane under mild conditions, achieving a methane activation rate of up to 6.7% per hour under optimized parameters. In this study, microbubbles provided an extensive gas-liquid interface that promoted the formation of hydroxyl (OH˙) and hydrogen radicals (H˙), which facilitated the activation of methane, leading to the generation of methyl radicals (CH3˙). These species further participated in free-radical reactions at the interface, resulting in the production of ethane and formic acid. The microbubble system was optimized by adjusting gas-liquid interaction time, water temperature, and bubble size, with the optimal conditions (150 s of water-gas interaction, 15 °C, 50 μm bubble size) yielding a methane conversion rate of 171.5 ppm h-1, an ethane production rate of 23.5 ppm h-1, and a formic acid production rate of 2.3 nM h-1 during 8 h of continuous operation. The stability and efficiency of this process, confirmed through electron spin resonance, high-resolution mass spectrometry, and gas chromatography, suggest that microbubble-based methane activation offers a scalable and energy-efficient pathway for methane utilization.

  View details for DOI 10.1039/d4sc05773b

  View details for PubMedID 39364074

  View details for PubMedCentralID PMC11446311

• Visualization of the Charging of Water Droplets Sprayed into Air. The journal of physical chemistry. A Xia, Y., Xu, J., Li, J., Chen, B., Dai, Y., Zare, R. N. 2024

  Abstract

  Water droplets are spraying into air using air as a nebulizing gas, and the droplets pass between two parallel metal plates with opposite charges. A high-speed camera records droplet trajectories in the uniform electric field, providing visual evidence for the Lenard effect, that is, smaller droplets are negatively charged whereas larger droplets are positively charged. By analyzing the velocities of the droplets between the metal plates, the charges on the droplets can be estimated. Some key observations include: (1) localized electric fields with intensities on the order of 109 V/m are generated, and charges are expected to jump (micro-lightening) between a positively charged larger droplet and the negatively charged smaller droplet as they separate; (2) the strength of the electric field is sufficiently powerful to ionize gases surrounding the droplets; and (3) observations in an open-air mass spectrometer reveal the presence of ions such as N2+, O2+, NO+, and NO2+. These findings provide new insight into the origins of some atmospheric ions and have implications for understanding ionization processes in the atmosphere and chemical transformations in water droplets, advancing knowledge in the field of aerosol science and water microdroplet chemistry.

  View details for DOI 10.1021/acs.jpca.4c02981

  View details for PubMedID 38968601

• Spontaneous Reduction by One Electron on Water Microdroplets Facilitates Direct Carboxylation with CO2. Journal of the American Chemical Society Chen, H., Wang, R., Xu, J., Yuan, X., Zhang, D., Zhu, Z., Marshall, M., Bowen, K., Zhang, X. 2023; 145 (4): 2647-2652

  Abstract

  Recent advances in microdroplet chemistry have shown that chemical reactions in water microdroplets can be accelerated by several orders of magnitude compared to the same reactions in bulk water. Among the large plethora of unique properties of microdroplets, an especially intriguing one is the strong reducing power that can be sometimes as high as alkali metals as a result of the spontaneously generated electrons. In this study, we design a catalyst-free strategy that takes advantage of the reducing ability of water microdroplets to reduce a certain molecule, and the reduced form of that molecule can convert CO2 into value-added products. By spraying the water solution of C6F5I into microdroplets, an exotic and fragile radical anion, C6F5I•-, is observed, where the excess electron counter-intuitively locates on the σ* antibonding orbital of the C-I bond as evidenced by anion photoelectron spectroscopy. This electron weakens the C-I bond and causes the formation of C6F5-, and the latter attacks the carbon atom on CO2, forming the pentafluorobenzoate product, C6F5CO2-. This study provides a good example of strategically making use of the spontaneous properties of water microdroplets, and we anticipate that microdroplet chemistry will be a green avenue rich in new opportunities in CO2 utilization.

  View details for DOI 10.1021/jacs.2c12731

  View details for PubMedID 36668682