NiO/g-C3N4 quantum dots for photocatalytic CO2 reduction

Graphited C3N4 quantum dots (g-C3N4 QDs) exhibit an up-conversion effect, which allows them to absorb near-infrared light and emit light with a shorter wavelength. By introducing g-C3N4 QDs to the surface of petal-like NiO microtubes, NiO/g-C3N4 QDs composites are successfully synthesized. Various techniques have been adopted to characterize the morphology, structure, and composition of the NiO/g-C3N4 QDs composites, and the interaction between NiO microtubes and g-C3N4 QDs has been confirmed. The usage of sunlight by the composite materials is enhanced with the aid of the up-conversion effect of g-C3N4 QDs and the novel petal-like tubular structure of NiO, which considerably improves the photocatalytic conversion of CO2 to CH4 and CO. When compared to NiO microtubes, the yields of CO and CH4 on NiO/g-C3N4 QDs are 2.1 and 4.2 times higher, respectively. The expanded light response range and the synergistic catalysis between g-C3N4 QDs and NiO microtubes are the primary causes of the increased photocatalytic activity of CO2 reduction on NiO/g-C3N4 QDs.