Defect engineering borophene/bismuthene/MXene/black phosphorus van der Waals laminations for sensitive photoelectrochemical-electrostatic sensors

Abstract

Nowadays, the two-dimensional (2D) materials have shown broad prospects for their fascinating attributes, yet the ineluctable material defects still restrict their applications. Herein, a spin-coating technology is employed to establish few-layers borophene/bismuthene/Ti3C2Tx MXene/black phosphorus (BP) laminations, and then a photoelectrochemical-electrostatic coupling sensor is developed. It is demonstrated that the rough defects on the Si/Ag substrate can be patched by the upper few-layers borophene and bismuthene, and the residual defects on the Ti3C2Tx layer can be exactly patched by the as-derived TiO2 and the upper 2D BP layers. These 2D metals have been bounded with adjacent 2D semiconductors through van der Waals interactions to greatly depress the metal-induced gap states and enhance the carrier transport. Under just light irradiation or ambient electric field (AEF), the current response of the lamination electrode obviously increases, compared to that without the key BP cover layer. Further, the response can be promoted to 236.4 μA cm−2, stimulated by AEF combined with light irradiation, which is about 1.8 times and 19.4 times higher than that of light irradiation alone and AEF alone, respectively. These can be attributed to the defect engineering effect, by which the 2D materials constantly mending the defects.