Ti3C2 MXene-based Schottky photocathode for enhanced photoelectrochemical sensing

Nanomaterials are vital to the realization of photoelectrochemical (PEC) sensing platform that provides the sensitive detection and quantification of low-abundance biological samples. Here, this work reports a Schottky junction-based BiOI/Ti3C2 heterostructure, used as a photocathode for PEC bioanalysis. Specially, we realize in situ growth of flower-like BiOI on 2D intrinsically negatively charged Ti3C2 MXene nanosheet that endows BiOI/Ti3C2 heterostructure with admirably combined merits, noting in particular the generation of built-in electric field and the decrease of contact resistance between BiOI and Ti3C2. Under the visible light irradiation, the BiOI/Ti3C2 heterostructure-modified PEC platform displays superior cathodic photocurrent signal, while PEC response cuts down with the presence of l-Cysteine (L-Cys) as a representative analyte owing to the metal-S bond formation. The “signal-off” PEC sensing strategy shows good performance in terms of sensitivity, limit of detection (LOD, 0.005 nM) and stability. This research reveals the great potentials of MXene-based heterostructure in the application field of PEC sensor establishment.