Photoelectrochemical N2 -to-NH3 Fixation with High Efficiency and Rates via Optimized Si-Based System at Positive Potential versus Li0/

Xiaoran Zhang; Yanhong Lyu; Huaijuan Zhou; Jianyun Zheng; Aibin Huang; Jingjing Ding; Chao Xie; Roland De Marco; Nataliya Tsud; Viacheslav Kalinovych; San Ping Jiang; Liming Dai; Shuangyin Wang

doi:10.1002/adma.202211894

Photoelectrochemical N₂ -to-NH₃ Fixation with High Efficiency and Rates via Optimized Si-Based System at Positive Potential versus Li^0/

Adv Mater. 2023 May;35(21):e2211894. doi: 10.1002/adma.202211894. Epub 2023 Mar 30.

Authors

Xiaoran Zhang^{1

2}, Yanhong Lyu¹, Huaijuan Zhou³, Jianyun Zheng¹, Aibin Huang^{4

5}, Jingjing Ding¹, Chao Xie¹, Roland De Marco^{6

7}, Nataliya Tsud⁸, Viacheslav Kalinovych⁸, San Ping Jiang^{2

9}, Liming Dai¹⁰, Shuangyin Wang¹

Affiliations

¹ State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
² Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory, Foshan, 528216, China.
³ Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of Technology, Beijing, 100081, China.
⁴ State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China.
⁵ Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
⁶ School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
⁷ Department of Chemistry, School of Pure Science, College of Engineering, Science and Technology, Fiji National University, Samabula, P.O. Box 3722, Suva, Fiji.
⁸ Charles University, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, Holešovičkách 2, Prague, 18000, Czech Republic.
⁹ WA School of Mines: Minerals, Energy and Chemical Engineering, Curtin University, Perth, WA, 6102, Australia.
¹⁰ Australian Carbon Materials Centre (A-CMC), School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia.

PMID: 36905214
DOI: 10.1002/adma.202211894

Abstract

As a widely used commodity chemical, ammonia is critical for producing nitrogen-containing fertilizers and serving as the promising zero-carbon energy carrier. Photoelectrochemical nitrogen reduction reaction (PEC NRR) can provide a solar-powered green and sustainable route for synthesis of ammonia (NH₃ ). Herein, an optimum PEC system is reported with an Si-based hierarchically-structured PdCu/TiO₂ /Si photocathode and well-thought-out trifluoroethanol as the proton source for lithium-mediated PEC NRR, achieving a record high NH₃ yield of 43.09 µg cm^-2 h^-1 and an excellent faradaic efficiency of 46.15% under 0.12 MPa O₂ and 3.88 MPa N₂ at 0.07 V versus lithium(0/+) redox couple (vs Li^0/+ ). PEC measurements coupled with operando characterization reveal that the PdCu/TiO₂ /Si photocathode under N₂ pressures facilitate the reduction of N₂ to form lithium nitride (Li₃ N), which reacts with active protons to produce NH₃ while releasing the Li⁺ to reinitiate the cycle of the PEC NRR. The Li-mediated PEC NRR process is further enhanced by introducing small amount of O₂ or CO₂ under pressure by accelerating the decomposition of Li₃ N. For the first time, this work provides mechanistic understanding of the lithium-mediated PEC NRR process and opens new avenues for efficient solar-powered green conversion of N₂ -to-NH₃ .

Keywords: N 2-to-NH 3 fixation; lithium-mediated nitrogen reduction reaction; photoelectrochemical nitrogen reduction reaction; reaction mechanism.

Abstract

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