Cathodic photoelectrochemical sensor developed for glutathione detection based on carrier transport in a Ti3C2Tx/AgI heterojunction

Recently, cathodic photoelectrochemical (PEC) sensing has emerged as a convenient and efficient method for molecular detection and analysis. Novel photoactive materials are urgently required for the further development of advanced cathodic PEC sensors. In this study, an original photoactive material, the Ti3C2Tx/AgI heterojunction material (HM), was synthesized by combining the two-dimensional layered material Ti3C2Tx MXenes with the p-type semiconductor AgI. The Ti3C2Tx/AgI HM exhibited excellent PEC performance. The PEC process in the Ti3C2Tx/AgI HM under light irradiation was explored and demonstrated using Vienna abinitio simulation package (VASP) calculations. The Ti3C2Tx/AgI HM exhibited enhanced electron-hole separation and charge transport owing to the good electronic conductivity of Ti3C2Tx and improved interfacial electron transport from Ti3C2Tx to AgI. Therefore, a cathodic PEC sensor was developed for glutathione (GSH) detection. GSH acted as a reductant and consumed the electron acceptor to inhibit electron transfer, resulting in a decrease in photocurrent signals that was linear with the GSH concentration. The linear range was wide (1-10 μM), with a detection limit of 0.31 nM. The PEC sensor also displayed satisfactory selectivity and stability; thus, the findings provide insights into the design and construction of a PEC sensing platform without enzymes.