Insight into mechanism for remarkable photocatalytic hydrogen evolution of Cu/Pr dual atom co-modified TiO₂

The development of high-activity photocatalysts is crucial for the current large-scale development of photocatalytic hydrogen applications. Herein, we have developed a strategy to significantly enhance the hydrogen photocatalytic activity of Cu/Pr di-atom co-modified TiO₂ architectures by selectively anchoring Cu single atoms on the oxygen vacancies of the TiO₂ surface and replacing a trace of Ti atoms in the bulk with rare earth Pr atoms. Calculation results demonstrated that the synergistic effect between Cu single atoms and Pr atoms regulates the electronic structure of Cu/Pr-TiO₂, thus promoting the separation of photogenerated carriers and their directional migration to Cu single atoms for the photocatalytic reaction. Furthermore, the d-band center of Cu/Pr-TiO₂, which is located at -4.70 eV, optimizes the adsorption and desorption behavior of H*. Compared to TiO₂, Pr-TiO₂, and Cu/TiO₂, Cu/Pr-TiO₂ displays the best H* adsorption Gibbs free energy (-0.047 eV). Furthermore, experimental results confirmed that the photogenerated carrier lifetime of Cu/Pr-TiO₂ is not only the longest (2.45 ns), but its hydrogen production rate (34.90 mmol g^-1 h^-1) also significantly surpasses those of Cu/TiO₂ (13.39 mmol g^-1 h^-1) and Pr-TiO₂ (0.89 mmol g^-1 h^-1). These findings open up a novel atomic perspective for the development of optimal hydrogen activity in dual-atom-modified TiO₂ photocatalysts.