Promoting water splitting by transforming its presence status for enhanced hydrogen evolution

Abstract

Non-acidic hydrogen evolution systems have a low concentration of hydrogen ions, and the H₂ evolution reaction (HER) is often limited by the water dissociation step. Preparing catalysts that can accelerate water dissociation is a common method for achieving high-efficiency evolution of hydrogen. In the current work, the performance of a hydrogen evolution system was first improved by introducing CO₂ to transform the presence status of H₂O. According to density functional theory (DFT) calculations, water reacts with CO₂ to produce carbonic acid which can reduce the barrier of adsorbed H generation. Subsequently, under same pH conditions, a constructed dye-sensitized Ni–CO₂ system shows an H₂ evolution rate 1.5 times higher than that shown by dye-sensitized Ni. This result indicates that transforming the presence status of H₂O may be a new strategy for further improving H2 evolution efficiency.