Ultrafast Carbothermal Shock Synthesis of Intermetallic Silicides with Anion-Cation Double Active Sites for Efficient Hydrogen Evolution

Abstract

The exploration and elucidation of the active site of catalysts is crucial for advancing the comprehension of the catalytic mechanism and propelling the development of exceptional catalysts. Herein, it is unveiled that anionic Si and cationic Pt in platinum silicide (PtSi) intermetallic compounds, obtained by ultrafast Joule heating (PtSi JH), simultaneously function as dual active sites for the hydrogen evolution reaction (HER). Density functional theory calculations reveal that, when both Pt and Si simultaneously serve as the active sites, the Gibbs free energy of hydrogen adsorption is 0.70 eV, significantly lower than that of either Pt (1.14 eV) or Si (0.90 eV) alone. Furthermore, both Pt-H and Si-H species are monitored by in situ Raman during the HER process. Consequently, PtSi JH exhibits ultralow overpotentials of 14, 30, and 51 mV at current densities of 10, 50, and 100 mA cm⁻², respectively, outperorming commercial Pt/C and Si powder. More importantly, the Joule heating method represents a versatile approach for synthesizing a range of metal silicides including RhSi, RuSi_x, and Pd₂Si. Therefore, this work opens a new avenue for the identification of genuine active sites and explores promising metal silicide for HER electrocatalysis and beyond.