Photothermal Catalytic Conversion of CO₂ to CO over Z-Scheme Co₉S₈@W₁₈O₄₉ Nanotubular Heterostructures

The transformation of CO 2 into fuel and valuable chemical products has become an important means to reduce the emissions of greenhouse gases and mitigate the energy crisis. In addition, it is of great significance for achieving the carbon emission peak and carbon neutrality. Herein, Co 9 S 8 @W 18 O 49 with a one-dimensional nanotubular core–shell structure was synthesized using a three-step hydrothermal method for photothermal catalytic CO 2 reduction. The photocatalytic performance of Co 9 S 8 @W 18 O 49 was evaluated by assessing the production of CO under visible light. The results showed that the 25 wt %-Co 9 S 8 @W 18 O 49 exhibited an excellent CO production efficiency of approximately 27.4 μmol g –1 h –1, a notable 8.06-fold improvement compared to the pure W 18 O 49 sample. The creation of a heterojunction with a Z-scheme between W 18 O 49 and Co 9 S 8 nanotubes increased the CO 2 conversion efficiency and inhibited the recombination of photogenerated charge carriers. Moreover, density functional theory calculations confirmed that the Z-scheme heterojunction was formed. This work aimed to contribute valuable insights into the design of Z-scheme photocatalysts with improved activity, which was enhanced by the synergistic effect of photothermal activation.