Pt Single Atoms Outperforming Pd on Vo-TiO2 for Enhanced Photocatalytic Hydrogen Evolution

Green hydrogen serves as a crucial renewable energy source driving the transition of energy structures and advancing sustainable development. Photocatalytic technology represents one of the prominent approaches for green hydrogen production. Compared to traditional semiconductors, noble metal single-atom catalysts (SACs) have emerged as promising photocatalysts due to their high atomic utilization efficiency and superior catalytic activity. In this work, Pt and Pd single atoms were separately anchored onto oxygen vacancies (Vo) on the TiO2 surface via a facile photodeposition method, yielding Pt or Pd monometallic single-atom loaded catalysts (Pt SAs/Vo-TiO2 and Pd SAs/Vo-TiO2). The optimal photodeposition time was investigated. Results demonstrate that the hydrogen evolution rate of Pt SAs/Vo-TiO2 reached 2375.76 μmol h−1 gcat.−1, while that of Pd SAs/Vo-TiO2 achieved 1875.72 μmol h−1 gcat.−1. These values are 76.5-fold and 60.4-fold higher than that of pristine TiO2, respectively. Density functional theory (DFT) calculations reveal that the introduction of single atoms reduces the band gap of the catalyst, consistent with the experimental findings. This study provides optimal parameters for synthesizing efficient single-atom catalysts.