Theoretical Investigation on the Catalytic Performance of g-C₃N₄ Supported Single Metal Atom Catalysts for Hydrogen Evolution from NH₃BH₃

In this paper, density functional theory (DFT) is used to study the hydrogen evolution catalytic mechanisms of NH3BH3 using five different catalysts, including one pristine g-C3N4 and four single metal atoms that belong to the platinum group (i.e., Rh, Ru, Pd, and Pt) supported by g-C3N4 (denoted as M/g-C3N4 catalysts hereafter). In short, three possible reaction paths of NH3BH3 hydrogen evolution are studied for each catalyst, and the optimal reaction path is determined by comparing the energy barrier of each path's rate-limiting step. We find that the single metal atom catalysts supported by g-C3N4 can significantly improve the hydrogen evolution efficiency of NH3BH3, among which the Rh/g-C3N4 catalyst performs best among all the catalysts explored in this work. At the same time, the electronic structures of the five catalysts are calculated, which indicate that the band gaps of the five catalysts are inversely proportional to their catalytic activities. Our results not only explain the catalytic reaction mechanism reported in previous experimental studies from a microscopic view but also reveal the correlation between the physical properties of catalysts and their catalytic activity.