Co–Ni–P Nanoneedle Array Heterostructures with Built-In Potential for Selective Methanol Oxidation Coupled with H2 Evolution

Abstract

Electro-oxidation of methanol (MOR) coupling with the hydrogen evolution reaction (HER) is a meaningful innovation strategy to realize energy-saving production of H2 and value-added chemical products. In this study, a self-supported cobalt nickel bimetallic phosphide nanoneedle array (Co–Ni–P/NF) is designed to realize excellent bifunctional activity for the HER and MOR. Studies prove that the p–n heterogeneous junctions formed in between nickel phosphide and cobalt phosphide promote the accumulation of electrons on CoP, favoring the absorption of H* and boosting HER activity, whereas the increased MOR activity is due to in situ generated holes in Ni2P. Benefiting from the optimized interface/surface electronic structures, the Co–Ni–P/NF produces 100 mA cm–2 current density in a two-electrode electrolyzer with a significantly low cell voltage of 1.45 V. The faradic efficiencies up to 100% for both the HER and MOR are obtained, showing the excellent bifunctional catalytic activity of Co–Ni–P/NF nanoneedle arrays. This work throws light on developing novel bifunctional electrocatalysts for value-added chemical production and highly efficient hydrogen evolution.