Electroanalytical investigation of quantum-dot based deposition of metal chalcogenides on g-C3N4 for improved photochemical performance

ZnS passivation layer is deemed as a superior passivation layer; however, compositing it with another metal chalcogenide material may assists to control the innate high charge recombination in graphitic carbon nitride (g-C3N4) 2D material. In this work, we deposited ZnS and In2S3 quantum dots (QDs) on g-C3N4 separately and together in mutable way, so that the detrimental charge carrier is reduced and the optimal combination of g-C3N4 (ZnS/In2S3 or In2S3/ZnS) is realized via simplistic wet-chemical route. Among all the prepared samples, g-C3N4/ZnS/In2S3 (Eg = 2.67 eV) showed superior photocatalytic performance by degrading 93.98% RhB dye, indicating better control on charge carrier recombination in g-C3N4 as revealed by spectroscopic techniques utilizing photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). Whereas, pristine g-C3N4 degraded the dye by 38.97% and the degradation percentage got increased a little bit by deposition of g-C3N4/ZnS and g-C3N4/In2S3 single passivation layers (SPLs) i.e., 47.06% and 64%, respectively. However in g-C3N4/In2S3/ZnS, double passivation layer DPL degraded 70.72% of the dye.