Self-powered photoelectrochemical aptasensor for sensitive detection of Microcystin-RR by integrating TiO2/S-doped Ti3C2 MXene photoanode and MoS2/S-doped Ti3C2 MXene photocathode

Abstract

Screening sufficient Fermi level differentiation of photoeletrodes is significantly meaningful for developing high-performance self-powered photoelectrochemical (PEC) sensors. In this work, a dual-photoelectrode self-powered system was fabricated for sensitive detection of Microcystin-RR (MC-RR) by integration of the TiO2/S-doped Ti3C2 photoanode and MoS2/S-doped Ti3C2 photocathode. The introduction of S-doped Ti3C2 nanosheets synergistically integrated with semiconductors (TiO2 and MoS2) could generate the unique Schottky junctions, which could adjust the Fermi energy levels, facilitate the separation of electron-hole pairs and broaden light absorption, leading to high photoelectric conversion efficiency. The electric output of self-powered sensing systems was increased by the substantial inherent bias between the Fermi energy levels of various photoelectrodes and the complementary functions of Schottky junctions, which provided a necessary foundation for the development of sensitive sensors. After the immobilization of the MC-RR aptamer, a novel signal-off dual-photoelectrode self-powered sensor was constructed for sensitive detection of MC-RR based on steric hindrance effect. Moreover, the as-fabricated sensor exhibited prominent analytical performance including wide detection range (10−16 M to 10−9 M), low detection limit (3.4 × 10−17 M), good selectivity, stability and reproducibility, so as to be successfully applied to real sample analysis. The designing ideas of the proposed S-doped Ti3C2 MXene-based Schottky junctions can provide a foothold for the innovative construction of dual-photoelectrode internal-driven self-powered sensing platforms with satisfactory performance.