A robust floating oxygen-doped graphitic carbon nitride sheet for efficient photocatalytic CO2 conversion

Abstract

Photocatalytic CO₂ reduction offers a promising approach for converting CO₂ into valuable chemicals. However, typical conversion systems suffer from inefficient CO₂ mass transfer and complex recycling processes. In this study, we developed a floating sheet as a robust photocatalytic CO₂ conversion system by integrating graphitic carbon nitride (CN) nanosheets onto polytetrafluoroethylene (PTFE) fiber membrane, followed by oxygen (O) doping into the CN (CN-O) via oxygen-plasma treatment. The floatable CN-O/PTFE sheet exhibits slight wettability in water under 0.25 MPa of CO₂ pressure in our reactor system, facilitating the delivery of dissolved CO₂ to the CN-O photocatalyst surface. O-doping enhances the visible light absorption and improves the separation and transport efficiency of photogenerated electrons and holes due to O-doping-induced states in CN. Consequently, the floating CN-O/PTFE system achieves an exceptional photocatalytic CO₂ conversion rate of 102.3 μmol g^-1h^-1, approximately 4.8 times higher than a conventional CN-powder dispersion system in water. Moreover, the sheet demonstrates excellent cycling durability, with no significant exfoliation of the catalytic layer or reduction in CO₂ photoreduction activity after 20 consecutive cycles. This study presents a novel approach to designing photocatalytic systems for efficient CO₂ conversion.