Design and fabrication of nanoarchitectures of rGO-decorated ZnCo2O4 hybrid photocatalyst for high-efficiency solar fuel generation

Photocatalytic CO₂ reduction for solar fuel production has garnered significant attention due to its potential to address both the energy crisis and CO₂ pollution. In this study, ZnCo₂O₄-rGO hybrid catalyst, specifically ZnCO₂O₄/10% rGO and ZnCo₂O₄/20%rGO, were designed by ultrasonic-assisted hydrothermal method for photocatalytic CO₂ reduction to address energy and environmental challenges. We evaluated the photocatalytic reduction ability of CO₂ to methanol and observed that incorporating rGO significantly reduced the recombination of photogenerated electron–hole pairs, thereby enhancing the photocatalytic activity of ZnCo₂O₄. Among the synthesized photocatalysts, ZnCo₂O₄ with 20% rGO exhibited the highest photocatalytic performance, attributed to its narrow band gap and efficient charge mobility. The ZnCo₂O₄/20%rGO heterogeneous photocatalyst maintaining its effectiveness through five consecutive reaction cycles without observable degradation in catalytic activity. ¹³CO₂ isotopic experiment validated that the produced methanol was from the photoreduction of CO₂. This result demonstrates that after 10 h of irradiation, the yield of methanol was 145 µmol/g, which is significantly higher than that obtained with pristine ZnCo₂O₄ (66.2 µmol/g) and previously-reported photocatalysts. This underscores that ZnCo₂O₄/20% rGO is a simple, efficient, and promising visible-light-driven photocatalyst for the photoreduction of CO₂ into solar fuels.