Theoretical and experimental progress of metal electrocatalysts for the nitrogen reduction reaction

Abstract

Ammonia (NH₃) has extensive applications in various fields and is mainly produced under high-temperature and high-pressure via the Haber–Bosch process, which leads to massive energy consumption. Electrocatalytic N₂ reduction to NH₃ is an attractive alternative for ammonia synthesis under ambient conditions. Inspired by N₂-fixation in biology, metal-based materials have been generally considered as promising nitrogen reduction reaction (NRR) electrocatalysts. The catalytic properties of metal species are significantly affected by their size due to the structure–reactivity correlations. In this review, we highlight theoretical and experimental studies on electrocatalytic N₂ fixation with a focus on metal materials with different sizes (single atoms, metal nanoclusters, and metals and their alloy nanoparticles). The geometry structure and corresponding chemical properties will be discussed on the account of experimental and theoretical studies. Furthermore, we will summarize the modulation strategy of metal-based materials for optimized electrocatalytic performance in the NRR. By revealing the intrinsic connection between the electronic structure and the catalytic performance, we will provide a perspective on the future catalytic material design for the NRR.