WS 2 supported PtO x clusters for efficient photocatalytic CO 2 reduction: a DFT study.

Platinum (Pt) nanoparticles/nanoclusters are some of the most efficient cocatalysts for photocatalytic CO 2 reduction. Nevertheless, the produced CO can lead to a poisoning effect due to the strong adsorption strength of the Pt cocatalysts. Using density functional theory, PtO x clusters with variable sizes (Pt 4 O 6 , Pt 5 O 8 , Pt 7 O 10 , and Pt 8 O 13 ) are selected to load on WS 2 (PtO x -WS 2 ) for photocatalytic CO 2 conversion. The calculated results demonstrate that PtO x -WS 2 are highly stable, and the electron-rich PtO x clusters are beneficial for the photocatalytic CO 2 reduction. All the PtO x -WS 2 catalysts exhibit efficient photocatalytic performance for CO 2 reduction. Especially, Pt 4 O 6 -, Pt 5 O 8 -, and Pt 8 O 13 -WS 2 have acceptable or ultra-low Δ G max (Δ G for the rate-determining step) of 0.57, 0.23, and 0.48 eV to produce CH 3 OH, HCOOH, and CH 4 , respectively. The photocatalytic activities of PtO x -WS 2 are correlated with the adsorption strength of the key intermediates, and the strong interactions between PtO x -WS 2 and *COOH or *HCOO can lower the free energy changes for the first hydrogenation step. More importantly, PtO x -WS 2 can also weaken the adsorption strength of *CO and *HCOOH, which are conducive to forming *CHO. This work gives an in-depth insight to design novel catalysts and promote their catalytic activity for photocatalytic CO 2 reduction.