Synergistic effect of cobalt in hierarchical carbon nitride nanorods (HCNNR) with promising charge transfer rate by hole scavenger for stimulating solar H-2 production

Abstract

One-dimensional (1D) hierarchical carbon nitrides nanorods (HCNNRs) mediated by cobalt was designed and synthesized using a template free hydrothermal approach for improving solar light assisted H(2 )evolution. The performance of 1D HCNNTs was significantly enhanced compared to bulk g-C(3)N4 due to larger active surface area, more visible light utilization and superior charge carrier along the unidirectional flow pathways. The 2% Co/HCNNRs (1D) exhibited excellent photocatalytic efficiency and optimal H-2 yield reached up to 620 mu mol g(-1), which is 11.27 and 17.71 folds more than it was attained with pure HCNNR and bulk g-C3N4, respectively. This reveals that 1D structure helps to accelerate charge transport, whereas, Co works as a mediator to trap electrons, thus improving photocatalytic performance. The crucial operating parameters such as sacrificial reagents, feed concentration and catalyst loading were further optimized based on highest H-2 evolution. Interestingly, mass transfer, charge transfer and amount of photoinduced charges were greatly dependent on the operating parameters. Higher methanol and lower TEOA concentration were beneficial to yield highest photoactivity and stability. This work provides new approach to construct template free 1D nanorods and would be beneficial to enhance performance in other solar energy related applications.