A novel approach for ultrasensitive estradiol detection based on single-layer MXene-based MX@TiO

A MXene-TiO₂ composite (MX@TiO₂) was successfully synthesized by employing single-layer MXene as a substrate and partially oxidizing it via an in-situ growth method. Subsequently, CdSe quantum dots (QDs) were coupled with this composite to construct an MX@TiO₂/CdSe heterojunction, which demonstrated remarkable photoelectric performance. The favorable energy level alignment between MX@TiO₂ and CdSe QDs significantly enhanced the separation efficiency of photogenerated electron-hole pairs at their interface. Meanwhile, the high conductivity of MXene not only facilitated rapid charge transfer but also inhibited the agglomeration of TiO₂ and CdSe QDs, thereby improving light absorption and photoelectric conversion efficiency while reducing charge recombination. Based on the MX@TiO₂/CdSe electrode, an ultrasensitive photoelectrochemical (PEC) sensor was developed for the efficient and accurate detection of estradiol (E₂) in real water samples. The sensor exhibited a wide detection range from 10⁻² to 10³ nmol·L⁻¹, with a low detection limit of 0.0082 nmol·L⁻¹, along with high stability, selectivity, and reproducibility. This work provides a feasible strategy for designing heterojunction-based photoactive materials for photoelectrochemical (PEC) sensing and offers new insights into developing sensitive biosensing for E2 detection.