Core–Shell Structured Cu(OH)2@NiFe(OH)x Nanotube Electrocatalysts for Methanol Oxidation Based Hydrogen Evolution

Electrochemical water splitting is considered to be a clean approach for hydrogen production. However, a large overpotential is required for the water oxidation reaction due to its sluggish kinetics, which leads to high energy consumption and low hydrogen production efficiency. Herein, copper hydroxide@nickel–iron hydroxide (Cu(OH)2@FeNi(OH)x) core–shell nanotube electrocatalysts are developed for an alternative methanol oxidation reaction to replace the conventional water oxidation reaction for boosting hydrogen evolution with less energy consumption. The average diameter of the Cu(OH)2@FeNi(OH)x nanotube is about 250 nm, and the surface is covered with FeNi(OH)x nanoflakes. The Cu(OH)2@FeNi(OH)x electrocatalysts demonstrate remarkable activity toward methanol oxidation, which require an anodic potential of only 1.32 V vs RHE to deliver a current density of 60 mA cm–2, being 160 mV lower than that of water oxidation. The lower potential of anodic reaction coupled with cathodic hydrogen evolution showcases the energy-saving capability in hydrogen production from water splitting. Moreover, methanol is exclusively converted into value-added formate with high selectivity and high Faradaic efficiency close to 100% in a wide potential range. The Cu(OH)2@FeNi(OH)x electrocatalysts also exhibit excellent stability for methanol–water coelectrolysis to produce pure hydrogen fuel and formate value-added chemicals.