Cu-NPs embedded 1D/2D CNTs/pCN heterojunction composite towards enhanced and continuous photocatalytic CO2 reduction to fuels.

Well-designed 1D/2D composite, consisting of carbon nanotubes modified protonated carbon nitrides (CNTs/pCN) embedded with Cu-NPs were synthesized by a facile sonicated assisted chemical method. The performance of catalysts towards dynamic CO 2 reduction to selective fuels was conducted under UV/visible light irradiations in a continuous flow photoreactor. Photo-activity of g-C 3 N 4 for CO production was increased by 2.38 folds after surface charge modification due to faster charge carrier separation. Loading 3 wt% Cu and 0.5 wt% CNTs into pCN gave highest activity for the production of CO, CH 4 and CH 3 OH under visible light. The highest CO yield as the main product over Cu-CNTs/pCN composite was 560 μmole g-cat−1 h−1, a 1.21, 1.36, 3.78 and 9.03 folds higher than using Cu/pCN, CNTs/pCN, pCN and g-C 3 N 4 samples, respectively. This significantly enhanced photo-activity can be attributed to visible light absorption and multi-stage charges separation in the presence of Cu/CNTs. More interestingly, CO obtained under visible light was 4 times higher than using UV-light, while performance for CH 4 production was 14 folds higher with visible light than using UV-light under the same operating conditions. Among the different catalyst loadings, 150 mg gave highest productivity, evidently due to limitations in exposed catalyst active surface area. Additionally, Cu-CNTs/pCN photocatalyst prevailed excellent stability in cyclic runs for continuous CO 2 reduction. The findings of this work would be attractive for the development of CO 2 conversion systems with renewable fuels production under solar energy. Unlabelled Image • Well-designed 1D/2D CNTs/g-C 3 N 4 heterojunction tested for CO 2 conversion to fuels. • Cu-MWCNTs/pCN hybrid yielded CO, CH 4 and CH 3 OH under UV and Visible light. • Yield of CO over Cu-CNTs/pCN was 9 folds higher than using g-C 3 N 4 under visible light. • Synergistic effect of Cu/CNTs promoted g-C 3 N 4 activity for CO 2 conversion to CO. • Cu-CNTs/pCN prevailed stability in cyclic-runs for CO/CH 4 evolution under visible light. [ABSTRACT FROM AUTHOR]