Protecting and Enhancing the Photoelectrocatalytic Performance of InGaN Nanowires toward Nitrogen Reduction to Ammonia Synthesis
Paulraj Gnanasekar, Karthik Peramaiah, Huafan Zhang, Mathan K. Eswaran, Rakesh R. Pradhan, Udo Schwingenschlögl, Tien Khee Ng, Qiaoqiang Gan, K. Jeganathan, Kuo‐Wei Huang, Boon S. Ooi
Abstract
The photoelectrochemical (PEC) reduction of nitrogen (N 2 ) to ammonia (NH 3 ) has emerged as a potential alternative to the conventional Haber–Bosch approach as the solar energy-driven process reduces energy consumption. In this work, PEC N 2 reduction is demonstrated with indium gallium nitride (InGaN) nanowires deposited with molybdenum carbide (Mo 2 C) co-catalyst. Interestingly, the incorporation of a GaN buffer layer between InGaN and Mo 2 C forms a suitable band alignment for rapid photogenerated charge carrier separation for the N 2 reduction reaction (NRR). Impressively, a maximum NH 3 production yield and Faradaic efficiency of 7.93 μg·h –1 ·cm –2 and 15.39%, respectively, is achieved at −0.2 V vs the reversible hydrogen electrode with the unique band structure of the Mo 2 C/GaN/InGaN photoelectrode. Density functional theory calculations reveal the favorable Gibbs free energy and efficient charge transfer process of the unique band structure of Mo 2 C/GaN/InGaN for effective NRR.