Recent advances in photoelectrochemical ammonia synthesis

Abstract

Ammonia is indispensable to agriculture and energy applications, but its conventional synthesis through the Haber-Bosch process remains both energy- and carbon-intensive. These concerns have driven interest in renewable-powered ammonia synthesis. The photoelectrochemical reduction of nitrogen and nitrate in aqueous electrolytes presents a promising alternative, converting solar energy into ammonia by integrating the advantages of electrochemical and photochemical methods. This process involves the use of photoelectrodes consisting of semiconductors that harness solar energy to excite electrons, and co-catalysts that facilitate electron transfer to reactants in the electrolyte. In this review, we examine recent developments in photoelectrode design for photoelectrochemical ammonia synthesis, with a particular focus on material properties such as semiconductor composition, band structure, surface morphology, co-catalyst selection, and emerging strategies that influence catalytic activity and selectivity. This review aims to provide a comprehensive overview of photoelectrode applications in solar-driven ammonia synthesis.