fig4

Figure 4. (A) CO evolution over time of V_Zn-ZIS, UCNPs, UCNPs@V_Zn-ZIS and UCNPs@ZIS; (B) Controlled photocatalytic CO₂ reduction experiments in the absence of CO₂, light or photocatalyst; (C) Carbon labeling experiment of the generated product using ¹³CO₂ as the feed gas; (D) Photocatalytic CO₂ reduction activity of UCNPs@V_Zn-ZIS with different mass ratio; (E) Photocatalytic stability test of UCNPs@V_Zn-ZIS; (F) Comparison of CO generation rate under NIR irradiation of UCNPs@V_Zn-ZIS with recent reported photocatalysts. V_Zn-ZIS: Zn vacancy-rich ZnIn₂S₄; UCNPs: up-conversion nanoparticles; NIR: near-infrared.