Well-designed V2AlC MAX supported g-C3N4/TiO2 Z-scheme heterojunction for photocatalytic CO2 reduction through bi-reforming to produce CO and CH4
Muhammad Tahir
Abstract
Well-designed V 2 AlC MAX supported g-C 3 N 4 /TiO 2 Z-scheme heterojunction was synthesized and tested for photocatalytic CO 2 reduction through bi-reforming under UV and visible light in batch and continuous photoreactors. Compared to V 2 AlC/g-C 3 N 4 , V 2 AlC/TiO 2 produced 2.17 times more CO and 6.40 times more CH 4 , along with H 2 . The highest CO production of 14644 μmol g −1 h −1 was obtained over V 2 AlC-g-C 3 N 4 /TiO 2 composite at a selectivity of 20.21 %. Similarly, CH 4 and H 2 production of 56567 and 1253 μmol g −1 h −1 was obtained, which were 11.11 and 169.9 folds higher for CH 4 and 2.77 and 2.32 folds higher for H 2 production compared to using g-C 3 N 4 /TiO 2 and V 2 AlC/TiO 2 , respectively. The efficient generation and separation of charge carriers were achieved by the Z-scheme heterojunction of g-C 3 N 4 /TiO 2 with V 2 AlC MAX cocatalysts, which led to a greatly increased photocatalytic activity . Using a continuous process, the production of CO was decreased by 1.12 folds, whereas the production of methane disappeared and the reaction pathway was the conversion of CO 2 to CO. Using methanol with UV light resulted in higher production of protons and hydrogen, achieving the highest quantum efficiency. The stability study further confirmed the continuous evolution of CO, CH 4 , and H 2 over four cycles.