Construction of C3N4/CdS nanojunctions on carbon fiber cloth as a filter-membrane-shaped photocatalyst for degrading flowing wastewater

Abstract

Photocatalysis has become an exciting and energy-saving technology for wastewater purification, but its practical applications have been limited by the difficulty involved in obtaining efficient and easily recyclable macroscale photocatalysts. Herein, we report the construction of C3N4/CdS nanojunctions on carbon fiber (CF) cloth as a filter-membrane-shaped photocatalyst. CF/C3N4/CdS cloth exhibits enhanced photoabsorption and photocurrent. Under visible light irradiation, CF/C3N4/CdS cloth shows improved photocatalytic activity for different pollutants (99% methylene blue (MB), 98% acid orange 7 (AO7), 81% tetracycline (TC), 81% Cr(VI)), compared with CF/C3N4 cloth (99% MB, 74% AO7, 48% TC, 20% Cr(VI)) and CF/CdS cloth (35% MB, 10% AO7, 47% TC, 48% Cr(VI)). Furthermore, with CF/C3N4/CdS cloth as a filter-membrane-shaped photocatalyst, the removal rate for TC and Cr(VI) was found to increase up to 73% and 83% after a 6 grade reaction, respectively, higher than that obtained for CF/C3N4 cloth (52% TC, 22% Cr(VI)) or CF/CdS cloth (50% TC, 42% Cr(VI)). The improved photocatalytic activity of CF/C3N4/CdS cloth results from the construction of C3N4/CdS nanojunctions, which not only confers stronger photoabsorption but also results in the efficient separation of photogenerated electron-hole pairs. In particular, several possible pathways for TC degradation were proposed based on the intermediate products formed. Therefore, CF/C3N4/CdS cloth can act as an efficient and recyclable filter-membrane-shaped photocatalyst for dealing with flowing wastewater, and it also provides new perspectives for the development of flexible macroscale photocatalysts.