Ti₃C₂ MXene-based Schottky Photocathode for Enhanced Photoelectrochemical Sensing

Abstract

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.