Predictive Theoretical Model for the Selective Electroreduction of Nitrate to Ammonia

Tong Mou; Yuting Wang; Peter Deák; Huan Li; Jun Long; Xiaoyan Fu; Bin Zhang; Thomas Frauenheim; Jianping Xiao

doi:10.1021/acs.jpclett.2c02452

Predictive Theoretical Model for the Selective Electroreduction of Nitrate to Ammonia

J Phys Chem Lett. 2022 Oct 27;13(42):9919-9927. doi: 10.1021/acs.jpclett.2c02452. Epub 2022 Oct 18.

Authors

Tong Mou^{1

2

3}, Yuting Wang⁴, Peter Deák³, Huan Li^{1

5}, Jun Long¹, Xiaoyan Fu¹, Bin Zhang⁴, Thomas Frauenheim^{2

3

6}, Jianping Xiao^{1

5}

Affiliations

¹ State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian116023, P. R. China.
² Shenzhen JL Computational and Applied Research Institute, Shenzhen518131, P. R. China.
³ Bremen Center for Computational Materials Science, University of Bremen, Bremen28359, Germany.
⁴ School of Science, Institute of Molecular Plus, Tianjin University, Tianjin300072, P. R. China.
⁵ University of Chinese Academy of Sciences, Beijing100049, P. R. China.
⁶ Beijing Computational Science Research Center, Beijing100193, P. R. China.

PMID: 36256962
DOI: 10.1021/acs.jpclett.2c02452

Abstract

The electrochemical reduction of nitrate (eNO₃RR) emerges as a promising route for decentralized ammonia synthesis. However, the competitive production of nitrite at low overpotentials is a challenging issue. Herein, using the combination of density functional theory and microkinetic modeling, we show that the selectivity for NH₃ surpasses that of NO₂^- at -0.66 V_RHE, which nicely reproduced the experimental value on titania. NH₂OH* → NH₂* is the kinetically controlling step at a low overpotential for NH₃ generation, while NO₂* → HNO₂ has the highest barrier to producing nitrite. Based on these mechanistic insights, we suggest that ΔG₁ (NH₂OH* → NH₂*) - ΔG₂ (NO₂* → HNO₂) can serve as a descriptor to predict the S(NO₂^-)/S(NH₃) crossover potential. Such a model is verified by the experimental results on Ag, Cu, TiO_2-x, Fe₃O₄, and Fe-MoS₂ and can be extended to the Au catalyst. Thus, this work sheds light on the rational design of catalysts that are simultaneously energy-efficient and selective to NH₃.