Surface Valence State Effect of MoO2+x on Electrochemical Nitrogen Reduction. Issue 12 (20th February 2022)

• Record Type: Journal Article
• Authors: Wang, Jiaqi; Jiang, Zhou; Peng, Guiming; Hoenig, Eli; Yan, Gangbin; Wang, Mingzhan; Liu, Yuanyue; Du, Xiwen; Liu, Chong
• Is Part Of: Advanced science. Volume 9:Issue 12(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-20
• Subjects: ammonia yield -- cluster -- nitrogen reduction reaction -- quantitative isotope labeling -- valence effect; Science -- Periodicals; 505
• DOI: 10.1002/advs.202104857
• Languages: English
• ISSNs: 2198-3844

Abstract

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 MoO4 2− in alkaline electrolytes. Here, a MoO2+ x catalyst enriched with surface Mo 6+ is reported. The Mo 6+ is stabilized by a native oxide layer to prevent corrosion and its speciation is identified as (MoO3 ) n clusters. This native layer with Mo 6+ 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 −1 h −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 Mo 6+ etched away. The accuracy of experimental results for NRR is confirmed by various control experiments and quantitative isotope labeling. Abstract : Surface Mo 6+ is designed and stabilized on a corrosion‐resistance MoO2+ x catalyst to enable the study of the Mo valence effect on electrochemical nitrogen reduction. The as‐prepared MoO2+ x shows a significantly higher ammonia yield than that of the MoO2 with Mo 6+ etched away, proving the effectiveness of surface Mo 6+ in catalyzing nitrogen reduction.