High-Efficiency Photoelectric Activity of InP/ZnS Quantum Dots Modulated by Iron Single-Atom Catalyst for Sensitive Photoelectrochemical Biosensing

The development of a green photoelectrochemical (PEC) active material and the manipulation of its carrier migration are of paramount importance for achieving high-performance PEC biosensing. In this study, we engineered a PEC heterojunction involving green InP/ZnS quantum dots (InP/ZnS QDs) with a sulfur-doped Fe–N–C single-atom catalyst (Fe–S/N–C) through electrostatic self-assembly. In the InP/ZnS@Fe–S/N–C heterojunction structure, InP/ZnS QDs significantly enhance the generation of photoinduced carriers due to its exceptional photophysical features, while Fe–S/N–C efficiently manipulates the transfer of interfacial electrons, driving a high-efficiency photoelectric conversion efficiency as demonstrated by a 5.6-fold photocurrent enhancement relative to pure InP/ZnS QDs. Coupling with the efficient peroxide-like activity of Fe–S/N–C, the resultant InP/ZnS@Fe–S/N–C heterojunction was explored to fabricate a PEC biosensing platform for sensitive and selective detection of hydroquinone (HQ) and glucose through synergistic signal amplification. The constructed PEC biosensor reveals outstanding analytical performance, showing a low limit of detection of 9.8 μM for HQ and 50 μM for glucose, respectively. This work provides a promising strategy to enhance the photoelectric response of green semiconductor QDs by coupling them with versatile single-atom catalysts for advancing PEC biosensing applications.