V modified Ni-based layer hydroxides for the electrocatalytic upgrading of amines to nitriles

Abstract

Electricity-driven water splitting is considered as a cost-effective and environmentally friendly way to produce hydrogen, but the anodic oxygen evolution reaction (OER) has largely limited its industrial application. High-efficiency electro-oxidation of benzylamine replacing the OER to promote hydrogen production is crucial but challenging. Herein, we demonstrate NiV-layered double hydroxides for the selective oxidation of benzylamine via the introduction of high valence vanadium into α-Ni(OH)₂ (a typical OER catalyst). Benefiting from the vanadium doping, the NiV-LDH electrode exhibits superior activity and selectivity for the benzylamine oxidation reaction (BOR). In particular, NiV-LDH requires an ultra-low potential of 1.33 V vs. RHE to achieve a current density of 10 mA cm⁻² and exhibits ∼99% selectivity for benzonitrile production over a wide potential range. Reaction mechanism studies indicate that the introduction of vanadium changes the electronic state of NiV-LDH/NF and the Lewis acidic sites on the surface, promoting the conversion of benzylamine. Furthermore, a NiV-LDH based two-electrode electrolyzer that coupled the BOR with the HER can deliver 10 mA cm⁻² at a voltage of 1.55 V, which can reduce the cell voltage by 240 mV relative to that of conventional overall water splitting.