@article{7a2be9926e2843099456e05cea755514,
title = "Surface Valence State Effect of MoO2+x on Electrochemical Nitrogen Reduction",
abstract = "The valance of Mo is critical for FeMo cofactor in ambient ammonia synthesis. However, the valence effect of Mo has not been well studied in heterogeneous nanoparticle catalysts for electrochemical nitrogen reduction reaction (NRR) due to the dissolution of Mo as MoO42− in alkaline electrolytes. Here, a MoO2+x catalyst enriched with surface Mo6+ is reported. The Mo6+ is stabilized by a native oxide layer to prevent corrosion and its speciation is identified as (MoO3)n clusters. This native layer with Mo6+ suppresses the hydrogen evolution significantly and promotes the activation of nitrogen as supported by both experimental characterization and theoretical calculation. The as-prepared MoO2+x catalyst shows a high ammonia yield of 3.95 µg mgcat−1h−1 with a high Faradaic efficiency of 22.1% at −0.2 V versus reversible hydrogen electrode, which is much better than the MoO2 catalyst with Mo6+ etched away. The accuracy of experimental results for NRR is confirmed by various control experiments and quantitative isotope labeling.",
keywords = "ammonia yield, cluster, nitrogen reduction reaction, quantitative isotope labeling, valence effect",
author = "Jiaqi Wang and Zhou Jiang and Guiming Peng and Eli Hoenig and Gangbin Yan and Mingzhan Wang and Yuanyue Liu and Xiwen Du and Chong Liu",
note = "Funding Information: This work was supported by the Pritzker School of Molecular Engineering at the University of Chicago. The authors thank the Soft Material Characterization Facility (SMCF) at the University of Chicago, Materials Research Science and Engineering Center (MRSEC) at the University of Chicago, Electron Microscopy Core, Research Resources Center (RRC) in University of Illinois at Chicago, and NMR facility at Northwestern University for characterizations. J.W. and Z.J. would like to acknowledge the financial support from the China Scholarship Council (CSC). Y.L. acknowledges the support by NSF (1900039 and 2029442), Welch Foundation (F-1959-20180324), and ACS PRF (60934-DNI6). This work used computational resources at XSEDE, TACC, and Argonne and Brookhaven National Labs. Funding Information: This work was supported by the Pritzker School of Molecular Engineering at the University of Chicago. The authors thank the Soft Material Characterization Facility (SMCF) at the University of Chicago, Materials Research Science and Engineering Center (MRSEC) at the University of Chicago, Electron Microscopy Core, Research Resources Center (RRC) in University of Illinois at Chicago, and NMR facility at Northwestern University for characterizations. J.W. and Z.J. would like to acknowledge the financial support from the China Scholarship Council (CSC). Y.L. acknowledges the support by NSF (1900039 and 2029442), Welch Foundation (F‐1959‐20180324), and ACS PRF (60934‐DNI6). This work used computational resources at XSEDE, TACC, and Argonne and Brookhaven National Labs. Publisher Copyright: {\textcopyright} 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.",
year = "2022",
month = apr,
day = "1",
doi = "10.1002/advs.202104857",
language = "English",
volume = "9",
journal = "Advanced Science",
issn = "2198-3844",
publisher = "Wiley-VCH Verlag",
number = "12",
}