Ligand Charge Donation–Acquisition Balance: A Unique Strategy to Boost Single Pt Atom Catalyst Mass Activity toward the Hydrogen Evolution Reaction
Xing Cheng, Bo Xiao, Yanhui Chen, Yueshuai Wang, Lirong Zheng, Yue Lu, Hongyi Li, Ge Chen
Abstract
Developing oxide supports for stabilizing single-atom catalysts enables more flexibility for tuning the electronic metal–support interactions (EMSIs) toward better catalytic activities. However, due to the electronegativity of oxygen anions, single-metal atoms often remain positively charged in these oxide supports and are poor at binding hydrogen species for the hydrogen evolution reaction (HER). Here, we report a ligand charge donation–acquisition balance strategy via an amorphous TiBxOy support to tune the EMSIs, which lead to the boosted HER mass activity of a single Pt atom catalyst. Based on spectroscopic characterizations, we found that Pt single atoms preferentially bonded with nearly neutral B atoms originating from TiB2-like species in the Ti–B–O framework rather than O anions. Density functional theory calculations reveal that due to the charge-transfer balance between B–O and B–Pt, the nucleophilicity of Pt was tuned to an optimum state, with an ideal hydrogen binding energy that benefits the HER. As a result, this Pt/TiBxOy catalyst achieves a high HER mass activity (37.8 A mg–1 Pt) and a turnover frequency (33.2 H2 s–1 Pt site–1) at an overpotential of 50 mV in an acid medium, outperforming commercial Pt/C by a factor of 34 and 33, respectively.