Hydrogen Spillover Intensified by Pt Sites on Single-Crystalline MoO₃ Interconnected Branches for Hydrogen Evolution

Hydrogen spillover is a well-recognized phenomenon in the electrocatalytic hydrogen evolution reaction (HER), and the spillover rate is highly dependent on metal–support interfaces. However, for the commonly used platinum (Pt) in HER, rational selection of the ideal support for intensifying spillover remains elusive. Herein, three-dimensional single-crystalline molybdenum oxide ( s -MoO 3 ) is proposed as an ideal support for active Pt sites. In contrast to these traditional support materials, the resultant s -MoO 3 manifests an interconnected branch-like morphology, a zigzag-type stepped edge, a porous surface, and a partially reductive surface. By virtue of these morphological and structural advantages of s -MoO 3 interconnected branches, the subsequent loading of Pt particles could induce the intensified spillover rate accompanied by the formation of the H(O) x MoO 3 intermediate and thus the enhanced activity for HER. It is expected that this work will enrich the current knowledge on hydrogen spillover mechanisms and offer an effective intensification strategy for support-type catalysts.