Co P@NiCo-LDH heteronanosheet arrays as efficient bifunctional electrocatalysts for co-generation of value-added formate and hydrogen with less-energy consumption

Abstract

Abstract The inefficiency of water splitting is mainly due to the sluggish anodic water oxidation reaction. Replacing water oxidation with thermodynamically more favorable selective methanol oxidation reaction and developing robust bifunctional electrocatalysts are of great significance. Herein, a hierarchical heteronanostructure with Ni–Co layered double hydroxide (LDH) ultrathin nanosheets coated on cobalt phosphide nanosheets arrays (CoxP@NiCo-LDH) are fabricated and used for co-electrolysis of methanol/water to co-produce value-added formate and hydrogen with saving energy. Benefiting from the fast charge transfer introduced by phosphide nanoarrays, the synergy in nanosheets catalysts with hetero-interface, CoxP@NiCo-LDH/Ni foam (NF) exhibits superior electrocatalytic performance (10 mA cm−2 @ 1.24 V and −0.10 V for methanol selective oxidation and hydrogen evolution reaction, respectively). Furthermore, CoxP@NiCo-LDH/NF-based symmetric two-electrode electrolyzer drives a current density of 10 mA cm−2 with a low cell voltage of only 1.43 V and the Faradaic efficiency towards the generation of formate and H2 are close to 100% in the tested range of current density (from 40 to 200 mA cm−2). This work highlights the positive effect of hetero-interaction in the design of more efficient eletrocatalysts and might guide the way towards facile upgrading of alcohols and energy-saving electrolytic H2 co-generation.