Constructing LaxCoyO3 perovskite anchored 3D g-C3N4 hollow tube heterojunction with proficient interface charge separation for stimulating photocatalytic H2 production

Abstract

LaxCoyO3 perovskite dispersed porous three-dimensional (3D) g-C3N4 hollow nanotubes to construct a Z-scheme nanocomposite were successfully synthesized via a wet impregnation assisted ultrasonic approach and were used for photocatalytic H2 generation in a liquid phase slurry photoreactor under visible light. A rhombohedral distorted LaCoO3 perovskite with 1.70 eV narrow band gap for improved optical properties was synthesized by the combination of coprecipitation and a hydrothermal method. Additionally, two-dimensional (2D) porous g-C3N4 with advantageous structural features was synthesized by a novel, facile, and cost-effective technique depicting exposed active sites with improved charge mobility and charge separation. A Z-scheme heterojunction by a wet impregnation assisted ultrasonic technique was constructed by LaCoO3 anchored onto hollow tubular porous g-C3N4 formed after the curling of flaked nanosheets into hollow tubes. Highest amount of H2 was generated by 15 wt % of LaCoO3 dispersed over porous g-C3N4 in the nanocomposite. The Z-scheme heterojunction generated H2 (800 µmol g-1) which was 1.41 and 1.77 times higher than pristine porous g-C3N4 and pristine LaCoO3, respectively, contributing to the improved visible light absorption and reduced band gap, mass transfer, charge mobility, and charge separation. The nanocomposite showed stability over three consecutive cycles. Also, the nanocomposite generated CH4 by the simultaneous occurrence of water splitting and photoreforming. The apparent quantum efficiency of the nanocomposite was also calculated and estimated to be 1.52 and 1.26 times improved over LaCoO3 and P-g-C3N4, respectively. Overall, this work gives insight into less costly and simple Z-scheme heterojunctions for solar to hydrogen conversion with high efficiency.