Harnessing Work Function Modulation for Hydrogen Evolution Catalysis in Mesoporous Bimetallic Pt-M Alloys: The Role of Mesopores in Work Function Optimization.

Work function (WF) influences electron transport and intermediates adsorption, enabling charge balance and catalytic optimization for the hydrogen evolution reaction (HER). However, the understanding of the role of mesopores and the relationship between composition and WF in pristine Pt-based alloys remains lacking. Herein, various mesoporous binary Pt-M alloy films (m-Pt-M, M = Pd, Rh, and Ru) with uniform pores and elemental distributions are synthesized, providing an experimental platform to investigate this relationship. It has been demonstrated that the WFs of m-Pt-M catalysts are strongly influenced by their compositions and mesoporous structures, thereby impacting HER activities. Among them, m-Pt-Ru with tailored WF lowers the thermodynamic energy barrier and accelerates the kinetic processes of HER. The mass activity of m-Pt-Ru in alkaline media is 17.8× and 5.1× higher, compared to Pt black and m-Pt, respectively. This work not only provides a simple method for the fabrication of well-defined binary metallic alloy films but also offers experimental insights into the rational design of highly efficient electrocatalysts with tunable WFs.