Photo-Driven Ammonia Synthesis via a Proton-Mediated Photoelectrochemical Device

Abstract

N₂ reduction reaction (NRR) by light is an energy-saving and sustainable ammonia (NH₃) synthesis technology. However, it faces significant challenges, including high energy barriers of N₂ activation and unclear catalytic active sites. Herein, we propose a strategy of photo-driven ammonia synthesis via a proton-mediated photoelectrochemical device. We used redox-catalysis covalent organic framework (COF), with a redox site (−C=O) for H⁺ reversible storage and a catalytic site (porphyrin Au) for NRR. In the proton-mediated photoelectrochemical device, the COF can successfully store e⁻ and H⁺ generated by hydrogen oxidation reaction, forming COF−H. Then, these stored e⁻ and H⁺ can be used for photo-driven NRR (108.97 umol g⁻¹) under low proton concentration promoted by the H-bond network formed between −OH in COF−H and N₂ on Au, which enabled N₂ hydrogenation and NH₃ production, establishing basis for advancing artificial photosynthesis and enhancing ammonia synthesis technology.