Biogenic aided fabrication of indium sulphide/g-C3N4 type-II heterostructure for sensitive detection and sunlight driven degradation of carbamazepine

The current work describes the ecofriendly and compatible synthesis of indium sulphide (In₂S₃:InS)-g-C₃N₄ (GCN) heterostructure. Chrysophyceae, commonly known as golden brown algae extract, was used as the reducing agent in a hydrothermal fabrication of InS/GCN. InS, GCN and InS/GCN were used to decorate a glassy carbon electrode (GCE) and evaluate its electrochemical performance using cyclic voltammetry (CV) and amperometric techniques for the detection of the carbamazepine (CBZ) drug. The amperometric method was more sensitive than cyclic voltammetry, detecting concentrations from 0.01 to 240 μM and having a limit of detection of 0.0139 μM. The CBZ recovery studies were conducted for tablets, suspensions, and urine samples, and the recovery percentage was in the range of 97.3 to 99.2 %, with the standard deviation less than 2.6 %. Additionally, CBZ was subjected to light-driven degradation studies in the presence of InS/GCN and found to degrade 81, 93, and 98 % under UV, visible, and sunlight sources, respectively. Various factors affecting degradation, like pH (pH 7), catalyst amount (40 mg) and concentration (10 mg L−1) of drug, were optimized to achieve maximum degradation. Liquid chromatography–mass spectroscopic (LC–MS) results helped predict the degradation pathway. Enhanced activity in InS/GCN could be attributed to the formation of a type II heterostructure with enhanced electron mobility and decreased charge transfer resistance. This new approach serves as a versatile material for use in electrochemistry, the pharmaceutical industry, and environmental remediation. © 2025 Elsevier B.V.