Efficacious CO₂ Photoconversion to C2 and C3 Hydrocarbons on Upright SnS-SnS₂ Heterojunction Nanosheet Frameworks

In this work, SnS-SnS₂ heterostructured upright nanosheet frameworks are constructed on FTO substrates, which demonstrate promising photocatalytic performances for the conversion of CO₂ and water to C2 (acetaldehyde) and C3 (acetone) hydrocarbons without H₂ formation. With post annealing in designated atmospheres, the photocatalytic activity of the SnS-SnS₂ heterostructured nanosheet framework is critically enhanced by increasing the fraction of crystalline SnS in nanosheets through partial transformation of the SnS₂ matrix to SnS but not obviously influenced by improving the crystallinity of the SnS₂ matrix. DFT calculations indicate that transformed SnS possesses the CO₂ adsorption sites with significantly lower activation energy for the rate-determining step to drive efficient CO₂ conversion catalysis. The experimental results and DFT calculations suggest that the SnS-SnS₂ heterojunction nanosheet framework photocatalyst experiences Z-scheme charge transfer dynamic to allow the water oxidation and CO₂ reduction reactions occurring on the surfaces of SnS₂ and SnS, respectively. The Z-scheme SnS-SnS₂ heterostructured nanosheet framework photocatalyst exhibits not only efficient charge separation but also highly catalytic active sites to boost the photocatalytic activity for CO₂ conversion to C2 and C3 hydrocarbons.