Graphdiyne-anchored ultrafine NiFe hydroxide nanodots electrocatalyst for water oxidation with high mass activity and superior durability

Abstract

Structural and interface engineering enable the optimization of electrocatalysts in terms of both activity and durability. Herein, the three-dimensional (3D) architecture graphdiyne nanowall (GDY) serving as scaffolds anchor metal cations to form the NiFe layered double hydroxide (LDH) nanodots/graphdiyne (NiFe ND/GDY) heterojunction electrocatalysts for water oxidation in alkaline solution. After tuning the loading amount of NiFe-LDH carefully, the NiFe ND displays ultrasmall nanometer size of 2.7 nm and intimate interfacial coupling with GDY. Owing to the optimized 0D/3D structure, strong interfacial forces and the unique properties of GDY, the resulting NiFe ND/GDY requires an overpotential of only 252 mV to deliver current density of 10 mA cm−2 and shows favorable kinetics with a small Tafel slope of 39.70 mV dec−1. Notably, the mass activity of NiFe ND/GDY heterojunction is 70 times higher than that of the commercial RuO2 (631 A g−1 vs. 9 A g−1 to RuO2, at η = 300 mV), and it exhibits a superior long-term stability (only 10% degradation during continuous electrolysis of 100 h). This work indicates that GDY can serve as a promising substrate to anchor the ultrafine nanoparticle catalysts for water oxidation or beyond.