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 H 2 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 Ni 2 P. 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.

Boosting Hydrogen Evolution by Methanol Oxidation Reaction on Ni-Based Electrocatalysts: From Fundamental Electrochemistry to Perspectives

“…(h) Polarization curves measured in 1.0 M KOH with or without 0.5 M methanol using developed Co–Ni–P as a bifunctional electrocatalyst. Reprinted from ref . Copyright 2023 American Chemical Society.…”

“…Further combination of an H-cell with Co–Ni–P/NF as bifunctional for HER and MOR, a cell voltage of 1.45 V, 220 mV lower than the WS reaction, is required to maintain a current density of 100 mA cm –2 (Figure h). This coupling reaction saves a lot of energy by producing hydrogen and formate with a 100% FE . Other examples of NF-supported heterostructures can be found to be excellent MOR electrocatalysts, demonstrating robust and stable catalytic performance. ,− …”