Abstract
Light-driven heterogeneous photocatalysis has gained great significance for generating solar fuel; the challenging charge separation process and sluggish surface catalytic reactions significantly restrict the progress of solar energy conversion using a semiconductor photocatalyst. Herein, we propose a novel and feasible strategy to incorporate dihydroxy benzene (DHB) as a conjugated monomer within the framework of urea containing CN (CNU-DHBx) to tune the electronic conductivity and charge separation due to the aromaticity of the benzene ring, which acts as an electron-donating species. Systematic characterizations such as SPV, PL, XPS, DRS, and TRPL demonstrated that the incorporation of the DHB monomer greatly enhanced the photocatalytic CO2 reduction of CN due to the enhanced charge separation and modulation of the ionic mobility. The significantly enhanced photocatalytic activity of CNU–DHB15.0 in comparison with parental CN was 85 µmol/h for CO and 19.92 µmol/h of the H2 source. It can be attributed to the electron–hole pair separation and enhance the optical adsorption due to the presence of DHB. Furthermore, this remarkable modification affected the chemical composition, bandgap, and surface area, encouraging the controlled detachment of light-produced photons and making it the ideal choice for CO2 photoreduction. Our research findings potentially offer a solution for tuning complex charge separation and catalytic reactions in photocatalysis that could practically lead to the generation of artificial photocatalysts for efficient solar energy into chemical energy conversion.
Highlights
The production of renewable fuels with rich CO2 as raw materials through solar energy has been considered the best solution for energy crises and environmental remediations [1,2,3,4,5].It is always attracting and has received much attention for generating renewable fuel from the conversion of CO2 through semiconductor-based photocatalysts [5,6,7,8]
The copolymerized CNU exhibits a clear enhancement of the SPV signal, indicating an increased charge separation due to the aromaticity of the benzene ring in the Carbon nitride (CN) framework, which acts as an electron-donating species
The results reveal that CNU-DHB15.0 showed good photocatalytic activity and stability in practically all of the four cycling runs, and no obvious decline was observed after long-term use
Summary
The production of renewable fuels with rich CO2 as raw materials through solar energy has been considered the best solution for energy crises and environmental remediations [1,2,3,4,5]. A variety of techniques have been used to modify CN, including doping, morphology tailoring in the form of nanorods, and hollow nano-spheres junction fabrication, crystal facet engineering, and surface modification [5,42,43,44] Inspired by these advancements, molecular engineering (copolymerization) has arisen as a new significant technique by incorporating new energetic organic conjugated monomers within the framework of CN to improve its photocatalytic properties [5,33,37,39,43,44]. The successfully grafted pyrene functional group onto the CN surface via a post copolymerization technique (Py-CN) shows unique biphasic photocatalytic activities that allow efficient CO2 photoreduction in aqueous solution while effectively oxidizing alkenes (C=C) in the organic phase. This effort will open up new possibilities to promote the use of copolymerized CN for CO2 photofixation under visible illumination
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