Synthesis of Z-scheme Ag2CrO4/Ag/g-C3N4 composite with enhanced visible-light photocatalytic activity for 2,4-dichlorophenol degradation

Designing and construction of highly efficient Z-scheme photocatalytic systems has received growing attention because of their unique advantages of excellent photogenerated carrier separation ability, complementary light absorption property and high redox capacities, which made them highly promising in refractory organic pollutants removing in the field of wastewater treatment. In this study, a narrow band gap Ag-based semiconductor Ag2CrO4 with broad visible light response range (lambda < 688 nm), sufficient oxidation capability of photogenerated hole and excellent photogenerated carrier separation ability was chosen to couple with g-C3N4 for enhancing the photocatalytic activity of g-C3N4. A series of Z-scheme Ag2CrO4/Agig-C3N4 composites were synthesized via facile in-situ growth strategy and photoreduction approach, and their photocatalytic performances for 2,4-dichlorophenol (2,4-DCP) degradation were evaluated under visible light irradiation (lambda > 420 nm). Benefiting from the broadband light utilization of the composite and efficient separation and transfer of photogenerated carriers, as well as the sufficient redox capacities of the photogenerated electrons and holes, the as-synthesized composites displayed remarkably enhanced photocatalytic activity for 2,4-DCP degradation, which was about 5.2 times as high as that over individual g-C3N4. Meanwhile, mechanism study through the active species trapping, electron spin resonance (ESR) experiments and band edge position estimation analysis provided evidences that the possible enhancing photocatalytic mechanism was ascribed to the Z-scheme. This work will shed light on design of other efficient g-C3N4-based Z-scheme photocatalytic systems for application in environmental remediation. (C) 2017 Elsevier B.V. All rights reserved.