Growth of C3N4 nanosheets on carbon-fiber cloth as flexible and macroscale filter-membrane-shaped photocatalyst for degrading the flowing wastewater

Abstract

For degrading the flowing wastewater, the ideal photocatalysts should be nanostructured filter-membrane with large area, excellent flexibility and high visible-light-driven photocatalytic activity. Herein, we report the design and preparation of C3N4 nanosheets on carbon-fiber (CF) cloth as filter-membrane-shaped photocatalyst. The growth of C3N4 nanosheets has been realized by using a dip-coating and thermal condensation method with carbon-fiber cloth as the substrate. The resulting cloth (area: 4×4cm2) is composed of carbon fiber (diameter: 15μm) bunches which are decorated with C3N4 nanosheets with the thickness of 30nm. CF/C3N4 cloth exhibits excellent flexibility and strong visible-light absorption at ∼450nm. When CF/C3N4 cloth (area: 4×4cm2) is floated on the polluted water, it can degrade 98% Rhodamine B (RhB) in 60min and 99.3% colorless parachlorophenol (4-CP) after 120min of visible-light irradiation. Interestingly, when CF/C3N4 cloth (area: 4×4cm2) as the filter-membrane is used to construct a new photocatalytic setup for degrading the flowing wastewater (rate: 1.5Lh−1) under visible-light irradiation, the degradation efficiency of RhB goes up from 18% to 92% with the increase of filtering/degrading grade from 1 to 7. Direct contact between CF/C3N4 cloth and pollutants is found to be unnecessary for the efficient degradation. Furthermore, free radical capture experiments confirm that both O2− and h+ play a major role in the system under visible light irradiation; and CF/C3N4 cloth exhibit excellent stability. Therefore, CF/C3N4 cloth has great potential to be used as an efficient, stable, macroscale filter-membrane-shaped photocatalyst for degrading the flowing wastewater.