Effects of Adsorbing Noble Metal Single Atoms on the Electronic Structure and Photocatalytic Activity of Ta3N5

Ta3N5 is one of the most promising candidates for photocatalytic water splitting in the visible light region, but overall water splitting has been seldom achieved, partially due to its very low H-2 evolution activity. Herein, we explored the influence of loading noble metal single atoms (M = Pt, Rh, Ir, and Ru) on the electronic structures and the performance of photocatalytic hydrogen generation of Ta3N5 by utilizing hybrid density functional calculations. The most favorable sites for depositing noble metal single atoms on the (100), (010), (001), and (110) surfaces of Ta3N5 are the low-coordinated N atoms. Due to charge transfer from metal adatoms to the Ta3N5 surface, the work function of the adsorbed surface is significantly smaller than the clean one, indicating enhanced surface activity. The adsorption of noble metal single atoms on the (100) and (110) surfaces with higher stabilities is in favor of transferring photoinduced electrons from valence bands to conduction bands of Ta3N5. The photocatalytic hydrogen evolution activities of different pure and M/Ta3N5 surfaces were evaluated from a thermodynamic viewpoint. According to the calculated results, it could be concluded that compared with the pristine semiconductor, all of the studied Ta3N5 surfaces with adsorbed noble metal single atoms exhibit superior activity for photocatalytic hydrogen evolution reaction (HER). The role of metal adatoms is to activate the surface atoms. The performances of Rh, Ir, and Ru single atoms are comparable to or even better than that of Pt single atoms as cocatalysts in photocatalytic hydrogen generation. The above knowledge may serve as a guideline for experimentalists to design better photocatalysts based on depositing proper noble metal single atoms on semiconductor surfaces.

Automated summary

Loading noble metal single atoms (M = Pt, Rh, Ir, and Ru) on the Ta3N5 surface significantly enhances its photocatalytic hydrogen generation performance. Adsorbing noble metal single atoms on (100) and (110) surfaces facilitates the transfer of photoinduced electrons, with Rh, Ir, and Ru single atoms showing comparable or better performance than Pt as cocatalysts. This knowledge can guide experimentalists in designing more efficient photocatalysts by depositing proper noble metal single atoms on semiconductor surfaces.