Mechanism Exploration of Hydrogen Evolution Reaction on Platinum Single Atom Catalyst Using Electrodeposition Technique

Due to global climate change and the energy crisis, the demand for low-cost, high-efficiency catalysts for hydrogen generation reaction (HER) is increasing. Platinum is the most suitable metal as the HER catalyst and has excellent catalytic activity compared with other transition metals. However, it is essential to reduce the amount of use in the catalyst due to its high cost and scarcity. The synthesis of Pt single atom catalyst is promising strategy to maximize atomic utilization efficiency and decrease the Pt content. In recent years, the research on Pt single atom catalyst has been actively conducted because of low platinum content and excellent catalytic activity per unit mass. However, it is tricky to synthesize highly uniform Pt single atom catalysts and interpret the distinguished catalytic activity of Pt single atom because Pt clusters or small nanoparticles could be unavoidably formed, and it led to remain obscure in interpreting the mechanism of Pt single atom catalyst. In this study, we developed a fast and facile method to synthesize single Pt atoms on carbon support (Pt SA/C) using electrodeposition technique. Pt particle formation was concisely controlled from Pt single atom to Pt nanoclusters (~2 nm) to Pt nanoparticles (3-5 nm). The very uniform Pt SA/C was identified through HR-TEM and XPS analysis, which is distinguished from the existing Pt single catalyst in which some platinum nanoclusters are coexist. The Pt SA/C displays excellent HER activity with a mass current density of 81.11 Amg_Pt^-1 which is overwhelmingly superior catalytic activity compared to the recent research works. the HER mechanism on Pt SA/C was interpreted using DFT calculation and CO stripping analysis. In this study, the finely dispersed Pt SA/C was synthesized using the electrodeposition technique and the unique catalytic activity and HER mechanism were identified.