WS2 supported PtOx clusters for efficient photocatalytic CO2 reduction: a DFT study

Abstract

Platinum (Pt) nanoparticles/nanoclusters are some of the most efficient cocatalysts for photocatalytic CO₂ 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 (Pt₄O₆, Pt₅O₈, Pt₇O₁₀, and Pt₈O₁₃) are selected to load on WS₂ (PtO_x–WS₂) for photocatalytic CO₂ conversion. The calculated results demonstrate that PtO_x–WS₂ are highly stable, and the electron-rich PtO_x clusters are beneficial for the photocatalytic CO₂ reduction. All the PtO_x–WS₂ catalysts exhibit efficient photocatalytic performance for CO₂ reduction. Especially, Pt₄O₆-, Pt₅O₈-, and Pt₈O₁₃-WS₂ have acceptable or ultra-low ΔG_max (ΔG for the rate-determining step) of 0.57, 0.23, and 0.48 eV to produce CH₃OH, HCOOH, and CH₄, respectively. The photocatalytic activities of PtO_x–WS₂ are correlated with the adsorption strength of the key intermediates, and the strong interactions between PtO_x–WS₂ and *COOH or *HCOO can lower the free energy changes for the first hydrogenation step. More importantly, PtO_x–WS₂ 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 CO₂ reduction.