MXenes modified by single transition metal atom for hydrogen evolution reaction catalysts

Abstract

Searching for noble-metal-free catalysts for hydrogen evolution reaction (HER) is crucial to the development of sustainable energy. Here, we systematically explored the HER catalytic performance of Ti2CO2, Ti3C2O2 and Ti3CNO2 modified by single transition metal atom via first-principles calculations. The modified catalysts behave outstanding catalytic performance with either the single atom or the O atom on the surfaces of MXenes as active sites when pH = 0. We found that Ti2CO2 doped with Cu, Ag and W at O site exhibit superb HER catalytic performance when pH = 0 with Gibbs free energies of hydrogen adsorption of −2.67*10−5, −2.78*10−4, and 3.37*10−4 eV, respectively. In addition, Cu and Pd directly anchoring on Ti2CO2 have dual-acitve-site mechanism for HER, indicating high efficiency. The enhanced performance for HER is attributed to the redistribution of electron after the introduction of single atom. Furthermore, Ti2CO2 doped with W at Ti site, Ti3C2O2 doped with Mo and W at Ti site, behave good catalytic performance via wide pH ranges under alkaline/neutral conditions. Their low water dissociation barriers imply excellent HER catalytic performance under both acidic and alkaline/neutral conditions. These explorations bring new prospect to the potential of Ti-based MXenes in HER catalysis.