Electrocatalytic CO2 reduction driven by renewable electricity offers a sustainable approach to producing valuable chemicals, though it is often hindered by low activity and selectivity. CuO, an important transition metal oxide, exhibits unique advantages in photoelectrocatalysis due to its high intrinsic catalytic activity and ability to serve as an active site for CO2 reduction. SiO2, a widely used substrate, facilitates Cu loading and increases the specific surface area of the catalyst. Meanwhile, g-C3N4 provides excellent visible-light responsiveness and efficient charge carrier mobility. Together, CuO, SiO2, and g-C3N4 are earth-abundant, low-cost, and chemically stable, making them ideal for solar-to-fuel applications. Here, a novel ternary heterojunction photocatalyst was constructed using SiO2, CuO, and g-C3N4. The heterostructure significantly improves light-harvesting efficiency, promotes efficient charge separation and transport, and simultaneously mitigates photogenerated carrier recombination and catalyst corrosion. The resulting SiO2@CuO/g-C3N4 catalyst demonstrates outstanding CO2 conversion performance, achieving a CO yield of 17 mmolg−1h−1 at 1.2 VRHE with nearly 100% selectivity. Moreover, this work systematically investigates the electrocatalytic CO2 reduction reaction (CO2RR) mechanism on Cu-based catalysts, offering insights into the formation of high-value multicarbon products and highlighting the potential of rational heterojunction design in enhancing solar-driven fuel production efficiency.
Li et al. (2025) studied this question.