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.