Efficiently Triggering Ordered and Stable Oxidation Active Sites on Ni-Based Interfaces by Coordination with Nitrogen Family Anions for Glycerol Electrolysis

Abstract

Transition metal pnictide catalysts, especially Ni-based nitrides and phosphides, exhibit superior activity and selectivity in anodic electrocatalysis compared to oxides. However, the mechanisms underlying their enhanced performance remain unclear. This study synthesized Ni-based pnictides and control samples (NiAx, A = O, N, P) on nickel nanorod arrays (Ni NRAs) via plasma treatment. Among them, NiNx showed optimal performance for glycerol electrooxidation (GOR), achieving 10 and 50 mA∙cm-2 at 1.29 and 1.39 V, with a 94.3% Faraday efficiency for formate production. Mechanism analysis revealed that nitrogen coordination primarily improves GOR performance by enabling an optimized oxidative reconstruction process facilitated by -NOx linkages, which reduce the dehydrogenation energy barrier of Ni-based hydroxides, promoting the formation of highly active and structurally ordered NiOOH sites; in fact, the intrinsic activity of NiOOH was largely unaffected by N coordination. In contrast, Ni-POx and Ni-O systems exhibit inferior performance due to less efficient reconstruction. These results challenge the assumption that enhanced catalytic activity arises solely from Ni sites coordinated with non-oxygen heteroatoms. Instead, this work highlights the importance of oxidative reconstruction processes, providing insights into designing cost-effective and efficient anodic catalysts.

Keywords: Ni-based pnictides, Ni-based interface reconstruction, glycerol electrooxidation