Protecting and Enhancing the Photoelectrocatalytic Performance of InGaN Nanowires toward Nitrogen Reduction to Ammonia Synthesis

The photoelectrochemical (PEC) reduction of nitrogen (N2) to ammonia (NH3) 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 N2 reduction is demonstrated with indium gallium nitride (InGaN) nanowires deposited with molybdenum carbide (Mo2C) co-catalyst. Interestingly, the incorporation of a GaN buffer layer between InGaN and Mo2C forms a suitable band alignment for rapid photogenerated charge carrier separation for the N2 reduction reaction (NRR). Impressively, a maximum NH3 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 Mo2C/GaN/InGaN photoelectrode. Density functional theory calculations reveal the favorable Gibbs free energy and efficient charge transfer process of the unique band structure of Mo2C/GaN/InGaN for effective NRR.