Nanostructure Engineering via Intramolecular Construction of Carbon Nitride as Efficient Photocatalyst for CO2 Reduction

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 electrondonating
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.