Synergistic heterointerface engineering of Co9S8/Ni(OH)2 hierarchical nanosheets for remarkable overall water splitting

Abstract

Sustainable production of hydrogen from electrochemical water spitting by cost-effective and non-precious bifunctional electrocatalyst is of remarkable interest and extremely desirable. Here, a novel hierarchical Co9S8/Ni(OH)2 heterostructure with porous nanosheets was fabricated as the heterogeneous bifunctional electrodes to achieve remarkable water electrolysis. Synergistic coexistence of Co9S8 and Ni(OH)2 nanostructure with crystalline-amorphous feature can induce a large number of chemically coupled heterointerfaces as catalytically accessible active sites to accelerate electron transfer kinetics and enable a super-hydrophilic feature to contact electrolyte and release gas bubbles. Thus, such Co9S8/Ni(OH)2 heterostructure electrode verifies a remarkable electrocatalytic activity with low overpotentials of 274 mV at 100 mA cm−2 for OER and 109 mV at 10 mA cm−2 for HER. As assembled in a lab-made electrolyzer, the Co9S8/Ni(OH)2 heterostructures as bifunctional electrodes enable 1.51 V to achieve an overall water splitting at 10 mA cm−2, along with the outstanding stability at about 100 mA cm−2 up to 55 h. This work paves a bright way to design and construct non-precious materials as effective and advanced electrocatalysts for electrolysis in water.