Fabricating 2D/2D/2D heterojunction of graphene oxide mediated g-C3N4 and ZnV2O6 composite with kinetic modelling for photocatalytic CO2 reduction to fuels under UV and visible light

Two dimensional (2D) reduced-graphene-oxide/g-C3N4 modified 2D ZnV2O6 heterojunction for enhanced photocatalytic CO2 reduction has been investigated. The catalysts were fabricated using one-pot solvothermal method and were tested in a fixed-bed reactor under visible and UV-light. The ZnV2O6/RGO/g-C3N4 composite catalyst demonstrated excellent photoactivity for CO2 reduction to CO and hydrocarbons under visible light. The maximum CO yield rate of 2802.9 mu mol g(-1) h(-1) was obtained over the composite, which is 7.4 and 1.7 times higher than using g-C3N4 and ZnV2O6, respectively. The improved activity attributing to synergistic effect of 2D layer heterojunction with enhanced charges separation by RGO mediator under visible light. Comparatively, 2 times lower productivity was obtained under UV-light than visible-light due to higher visible-light absorption. The time-dependent kinetic-model was further developed to understand the influence of photocatalytic oxidation and reduction processes on the reaction chemistry. The model is based on Langmuir-Hinshelwood (L-H) mechanism to understand the formation rates of products during photocatalytic CO2 conversion with water vapours. Kinetic reveals surface reaction is a rate limiting step, which depends on the generation of charge carrier with higher light absorption. The findings from the experimental and kinetic-model would be useful to understand photo-catalytic reaction engineering in solar energy applications. [GRAPHICS] .

Automated summary

The study investigated a 2D ZnV2O6 heterojunction modified by reduced graphene oxide and g-C3N4 for enhanced photocatalytic CO2 reduction under visible light. The composite catalyst showed excellent photoactivity, with a maximum CO yield rate 7.4 and 1.7 times higher than using g-C3N4 and ZnV2O6 alone, respectively. The improvements were attributed to the synergistic effect of the 2D layer heterojunction and enhanced charge separation by the RGO mediator under visible light.