Taming Electrons in Pt/C Catalysts to Boost the Mesokinetics of Hydrogen Production

Abstract

Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties. Herein, we demonstrate a precise engineering strategy for the carbon surface chemistry of Pt/C catalysts—that is, for the electron-withdrawing/donating oxygen-containing groups on the carbon surface—to fine-tune the electrons of the supported metal nanoparticles. Taking the ammonia borane hydrolysis as an example, a combination of density functional theory (DFT) calculations, advanced characterizations, and kinetics and isotopic analyses reveals quantifiable relationships among the carbon surface chemistry, Pt charge state and binding energy, activation entropy/enthalpy, and resultant catalytic activity. After decoupling the influences of other factors, the Pt charge is unprecedentedly identified as an experimentally measurable descriptor of the Pt active site, contributing to a 15-fold increment in the hydrogen generation rate. Further incorporating the Pt charge with the number of Pt active sites, a mesokinetics model is proposed for the first time that can individually quantify the contributions of the electronic and geometric properties to precisely predict the catalytic performance. Our results demonstrate a potentially groundbreaking methodology to design and manipulate metal–carbon catalysts with desirable properties.

Keywords

• Mesokinetics model
• Catalyst descriptor
• Pt charge state
• Carbon surface chemistry
• Hydrogen generation activity