Photoreduction of carbon dioxide and photodegradation of organic pollutants using alkali cobalt oxides MCoO2 (M = Li or Na) as catalysts

Fabrication and characterization of ZnGa1.01Te2.13/g-C3N4 heterojunction with enhanced photocatalytic activity

The extensive consumption of fossil fuels increases CO2 concentration in the atmosphere, resulting in serious global warming problems. Meanwhile, the problem of water contamination by organic substances is another significant global challenge. We have successfully synthesized ZnGa1.01Te2.13/g-C3N4 (ZGT/GCN) composites for the first time as effective photocatalysts for both pollutant degradation and CO2 reduction. ZGT/GCN composites were synthesized by a simple hydrothermal method. The prepared photocatalysts were characterized by XRD, SEM, TEM-EDS, DRS, BET, PL, and XPS. The ZGT/GCN heterojunction exhibited considerably enhanced photocatalytic activity in the degradation of crystal violet (CV) as well as in the photoreduction of CO2 when compared to pure ZGT and GCN semiconductors. The optimal rate constant for CV degradation was obtained with the ZGT-80%GCN composite (0.0442 h-1), which is higher than the constants obtained with individual ZGT and GCN by 7.75 and 1.63 times, respectively. Moreover, the CO2 reduction yields into CH4 by ZGT-80%GCN was 1.013 μmol/g in 72 h, which is 1.21 and 1.08 times larger than the yields obtained with ZGT and GCN. Scavenger and ESR tests were used to propose the photocatalytic mechanism of the ZGT/GCN composite as well as the active species in the CV degradation.