Smart three-phase interface heterojunctions for effective photo(electro)catalytic N2 reduction to ammonia

Abstract

The versatile green ammonia is increasingly positioning itself as one of the key future energy carriers for the net-zero carbon landscape. Solar-driven nitrogen reduction reaction (NRR) offers a renewable, clean and mild ammonia synthesis pathway to replace the traditional Haber–Bosch process. However, this is a complex multiphase catalytic reaction that also involves multiple proton-coupled electron transfer processes. As result, the overall efficiency of NRR routes is generally constrained by the sluggish N₂ adsorption and activation, the competitive reduction between hydrogen and ammonia, and the limited performance of available photo(electro)catalysts. Recently, catalyst engineering strategies are putting the focus on the rational control of the interfacial chemistry involved in light-driven multiphase systems. Three-phase interface catalysts hold great potential to overcome the mass transfer limitations of conventional diphase systems, while improving charge separation and transfer for an overall higher NRR performance. This work focuses on this emerging research field, reviewing the reported advances in photocatalytic and photoelectrocatalytic NRR to ammonia using three-phase interface catalysts, but also covering design fundamentals and highlighting the major advantages and challenges that must be addressed.