Single-Atom Catalysts on GaN Nanowires: A Computational Discovery for Efficient Electrochemical Nitrogen Fixation

The electrochemical nitrogen reduction reaction (eNRR) offers a sustainable route to ammonia synthesis but faces challenges from competing hydrogen evolution and the inertness of the N≡N triple bond. Leveraging the unique properties of GaN nanowires (GaNNWs)─including their high surface area, superior stability against dissolution, and excellent electron transport capabilities─we present the first systematic computational screening of GaNNW-supported single-atom catalysts (SACs) for eNRR. Through spin-polarized density functional theory calculations, we evaluated 18 transition metal atoms from groups VB to VIII (3<i>d</i>-5<i>d</i>) anchored on defective GaNNWs. Among the candidates studied, Re@GaNNW emerges as a theoretically promising catalyst, exhibiting a calculated limiting potential of -0.34 V along the distal reaction pathway, which suggests the potential for favorable NRR activity. A low activation barrier (0.23 eV) from transition state calculations, along with solvation and dissolution analyses, confirms the catalyst's kinetic feasibility and electrochemical stability. Moreover, detailed electronic structure and charge transfer analyses elucidate the origin of the high NRR activity and selectivity. This study not only identifies a promising catalyst for eNRR but also provides mechanistic insights and a rational design framework for nanowire-supported SAC systems.