Modulating carbon-supported transition metal oxide by electron-giving and electron-absorbing functional groups towards efficient overall water splitting

Abstract

The efficiency of splitting water into hydrogen and oxygen is highly depended on the catalyst used. Enhancing the thermodynamics and/or kinetics of electrocatalytic reactions and redox property through organic–inorganic nanohybrids represents one of the most powerful strategies to boost the electrocatalytic performance of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a rational design of carbon-supported transition metal oxide grown on a nickel foam surface is reported, which synergistically integrates the thermodynamics and/or kinetics through modification of electronic structures with accelerated kinetics by adjusting electron-giving and electron-absorbing groups. SCN– modification experiment and pre - and post-catalytic analysis manifest that the Co/Fe-N formed between the Co/Fe metal and amino functional group serve as the center of HER. Operando Raman spectroscopy was utilized to explore the OER active intermediates present under catalytic conditions. Specifically, the catalyst requires only an overpotential of 1.466 V to reach 10 mA cm−2 with good stability over 100 h at various current densities between 20, 40, 60, 80 and 100 mA cm−2, superior to controlled transition metal oxides and noble metals. This is a viable and systematic strategy to prepare metal organic framework catalysts with appropriate functional groups that can be used for energy storage and conversion in multiple applications.