Electronic and structural modification of three-dimensional porous NiCo@NF as a robust electrocatalyst for CO2 emission-free methanol upgradation to boost hydrogen co-production

Abstract

Electrochemical hydrogen evolution reaction (HER) coupled with methanol oxidation reaction (MOR) is an innovative process to attain energy-efficient hydrogen generation with more valuable formate product co-generation. Herein, we present 3D porous bimetallic NiCo nanostructures with oxygen vacancies grown on a nickel foam surface (Ov-NiCo@NF) as efficient electrocatalysts that show integrated highly selective methanol oxidation along with hydrogen evolution. The electronic structure of Ov-NiCo@NF is tuned by surface oxygen vacancies that provide a high active surface area and optimum chemisorption energy for selective methanol upgradation to formate. The metallic porous nanostructures and interconnected dendritic growth of nanoparticles ensure electrolyte penetration, with faster gas release ability, that enhances charge transfer kinetics and suppresses support passivation during MOR and HER. The 3D porous Ov-NiCo@NF exhibits improved methanol conversion activity, requiring 1.30 and 1.42 V (vs RHE) to achieve 50 and 100 mA cm-2 current densities for MOR, respectively. Furthermore, an integrated two electrode setup (Ov-NiCo@NF//Ov-NiCo@NF) requires a cell voltage of 1.41 V to attain 25 mA cm-2 current density for methanol-upgrading-assisted water electrolysis, while a higher cell voltage (1.62 V) is required in the electrolyte without methanol (overall water splitting). © 2023 American Chemical Society.