Efficient Photoelectrocatalytic Synthesis of Ammonia by Superionic Conductor with Mixed Ion/Electron Conduction

Abstract

Abstract Photoelectrochemical (PEC) nitrate reduction shows substantial potential for solar‐to‐ammonia (NH 3 ) conversion. However, low electron density and disordered electron conduction of conventional catalysts result in limited performance and low Faraday efficiency. Herein, a FePS 2.66 Li 0.87 superionic conductor (SIC) is developed by introducing lithium ions into van der Waals immobile layered of FePS 3 catalyst. This layered crystal framework facilitates high‐concentration lithium ions confinement and long‐range diffusion at room temperature, transitioning the conduction mechanism from electronic to mixed ionic/electronic. The typical nanofluidic ion transport leads to a high ionic conductivity of 16.4 mS cm −1 at room temperature and enhanced electronic conductivity of 5 × 10 −6 S cm −1 . Furthermore, mobile lithium ions within interlayers enhance the interaction between the low‐lying 3 d yz orbitals of Fe interacting with 2 a 2 empty antibonding orbitals of NO 3 − . An excellent PEC ammonia production of 134.18 µmol cm −2  h −1 with 96.95% Faradaic efficiency is achieved, and the corresponding solar‐to‐NH 3 efficiency of 57.13% offers a promising pathway toward sustainable ammonia production.