Dual engineering of electronic structure and nanoconfinement for high-efficiency ammonia borane hydrolysis over PtCo-oxCNH catalysts

Abstract

Monodisperse PtCo bimetallic alloy nanoparticles (NPs) were successfully synthesized via a facile impregnation–reduction method utilizing oxidized carbon nanohorns (oxCNHs) as a high-surface-area support. The optimized Pt_1.5Co-oxCNH catalyst demonstrated exceptional performance for hydrogen evolution via ammonia borane (AB) hydrolysis under mild conditions (298 K), achieving a high turnover frequency (TOF) of 445 mol_H2 mol_Pt⁻¹ min⁻¹. This represents a 2.7-fold enhancement compared to the monometallic Pt-oxCNH benchmark and is accompanied by a significant reduction in the apparent activation energy. Synergistic electronic effects within the Pt_1.5Co alloy were identified as critical to this performance boost. Furthermore, the unique nanoconfined pore structure of the oxCNH support effectively stabilized the PtCo NPs, minimizing aggregation and maintaining a small particle size, thereby maximizing accessible active sites and enhancing catalyst stability. The exceptional catalytic activity stems from the optimized electronic structure of Pt, modulated by localized electron density transfer via the Co alloying effect, coupled with strong metal–support interactions between the NPs and the functionalized oxCNH surface. This work provides a strategic design principle for developing highly active and durable heterogeneous catalysts for efficient hydrogen production.