Promoting multielectron CO2 reduction using a direct Z-scheme WO3/ZnS photocatalyst

In this study, the WO3/ZnS Z-scheme-heterojunction photocatalyst was evaluated for the photocatalytic reduc-tion of CO2 in the presence of water vapor. The results demonstrated that the quantity of WO3 (5-20 wt%) significantly affects the growth of crystallite size of ZnS, the modulation of the conduction band (CB) potential, and ultimately, the production of light hydrocarbons. The influences of temperature, volumetric flow, and WO3 wt% in the heterostructured photocatalyst were analyzed in a continuous reaction system. The highest pro-duction rate of hydrocarbons at the lowest volumetric flow was achieved using a photocatalyst with 5 wt% WO3 with respect to ZnS (W(5%)Z), with propane (C3H8) and propylene (C3H6) as the main products. The observed effect was rationalized by the synergy between the crystallite size, CB potential, and formation of the hetero-junction, which led to enhanced electron transfer on the active surface sites of the W5%Z photocatalyst than on those of either ZnS or WO3. The remarkable performance of W(5%)Z was attributed to the high production of charge carriers and their fast transfer from the direct Z-scheme photocatalyst surface to the reactants, which promoted the reduction of CO2 molecules into C1-C3 hydrocarbons. The results indicate that the WO3/ZnS system is a good candidate for the chemical transformation of CO2 into valuable products and must be considered for further studies.

Automated summary

This study evaluated the application of the WO3/ZnS Z-scheme-heterojunction photocatalyst in the photocatalytic reduction of CO2. The quantity of WO3 was found to significantly affect the growth of ZnS crystallite size, conduction band potential modulation, and production of light hydrocarbons. The highest hydrocarbon production rate was achieved using a 5 wt% WO3 photocatalyst with respect to ZnS, with propane and propylene as the main products.