First-Principles Study on Stability and HER Activity of Noble Metal Single-Atoms on TiO2: The Effect of Loading Density

The highly dispersed “single-atom (SA)” catalysts on oxide supports significantly alter the catalytic reaction activity and selectivity and meanwhile save the catalyst utilization. However, preparation of SA catalysts remains a challenge up to now. An approach effectively evaluating the stability and activity is required. Herein, density functional theory (DFT)-based first-principles calculations were performed to evaluate the stability and photocatalytic hydrogen evolution reaction (HER) activity of noble metal (NM = Ag, Au, Pd, and Pt) SAs loaded on TiO2 support. The chemical potential-based thermodynamic model was employed to estimate the stability of SAs; the capability to trap photoelectrons on surface and free energy of hydrogen adsorption were used to estimate the photocatalytic HER activity of SAs. Compared to the (101) surface, the (001) surface is more feasible for preparation of NM SAs due to the “soft” structural character caused by incompletely saturated surface atoms. The stability of SAs on...