Hexagonal close-packed platinum–tin for efficient hydrogen production via aqueous phase reforming

Abstract

Aqueous phase reforming (APR) of alcohols is a promising on-site hydrogen (H₂) production technique for mobile H₂ applications, yet the catalytic effectiveness of APR catalysts is insufficient for practical applications. Herein, hexagonal close-packed phase platinum–tin intermetallic compounds (PtSn/C₃N₄) were identified to exhibit extraordinary activity for APR of methanol (CH₃OH) to H₂, with a turnover frequency of 56,024 h⁻¹. Furthermore, the H₂ productivity of PtSn/C₃N₄ is 1.5 times that of Pt₃Sn/C₃N₄. The nearly identical electron cloud density of surface Pt atoms and d-band center of PtSn/C₃N₄ and Pt₃Sn/C₃N₄ demonstrate the negligible influence of electronic effects on performance. Mechanism researches indicate that the excellent APR activity of PtSn/C₃N₄ is attributable to the geometric effect, where the shorter Pt–Sn bond length and lower Pt–Pt coordination numbers in comparison to Pt₃Sn suppress the formation of H-bond between *CO and H₂O* (*CO···H–OH*), weaken the co-adsorption of *CO and H₂O* , and reduce the energy requirement (0.60 vs. 0.92 eV) to further form HCOO* as the limiting step for APR of CH₃OH. This work not only provides efficient APR catalysts, but also advances basic research on the structure-activity relationship in catalysis.