Integration of C-dots with g-C3N4 nanosheet/Ag2CO3 nanocomposites as effective Z-scheme visible-light photocatalysts for removal of hazardous organic and inorganic contaminates

Abstract

A series of visible-light-induced g-C3N4 nanosheet/carbon dots/Ag2CO3 (denoted as NCN/C-Dots/AgCO) photocatalysts were achieved by an easy precipitation procedure. All the samples were investigated through various instruments and they showed exceptional activities in the removal of hazardous organic contaminates and hexavalent chromium ions. Among ternary nanocomposites, the NCN/C-Dots/AgCO (10%) nanocomposite demonstrated excellent ability for removal of RhB, which was almost 47.5, 11.7, and 5.1 times as high as the single CN, NCN, and NCN/C-Dots samples, respectively. Also, the rate constants over the ternary photocatalyst for the removal of MO and MB are 37.7 and 18.2-folds larger than the CN, respectively. Besides, the optimum nanocomposite demonstrated excellent activity for the reduction of Cr(VI), which is 13.6, 6.0, and 2.9-folds more than the CN, NCN, and NCN/C-Dots photocatalysts, respectively. The improved degradation ability of the NCN/C-Dots/AgCO (10%) nanocomposite was related to the quick segregation of produced charges, because the C-Dots act as electron mediator between NCN and AgCO. Moreover, the ·O2− was detected as the oxidative species in the photocatalytic reaction by the quenching tests. Furthermore, the photocatalytic mechanism was suggested as a Z-scheme mechanism in order to increase charges segregation and movement, which causes the supreme photodegradation ability. In addition, the RhB degradation intermediates such as benzoic acid and phthalic acid were identified by GC–MS. This study highlights the applications of exceedingly effective C-Dots adhered semiconductors in wastewater cleaning.