Ordered V2O5 Nanowire Bundles Enable Self-Powered Fast-Response Photoelectrochemical UV Detection

One-dimensional V 2 O 5 nanostructures, with their anisotropic crystal structure, accessible oxide/electrolyte interface, and short radial carrier transport distance, are promising photoelectrode materials for photoelectrochemical (PEC) detectors. However, controllably ordered V 2 O 5 nanowire bundles have yet to be achieved, and the photoresponse feasibility of such well-defined one-dimensional architectures requires further investigation. Herein, we present an alcohol-mediated hydrothermal approach to engineer directionally organized V 2 O 5 nanowire bundles and subsequently evaluate the self-powered PEC ultraviolet detection performance of a representative ethanol-derived sample. Alcohols with carbon chains of different lengths were employed to regulate the morphology of the V 3 O 7 ·H 2 O precursor, which was subsequently converted into orthorhombic V 2 O 5 by calcination while largely preserving its one-dimensional morphology. Among the investigated solvents, ethanol produced the most uniform and well-organized nanowire bundles, consisting of highly crystalline individual nanowires with an average diameter of approximately 61.09 nm. Using this ethanol-derived V 2 O 5 photoanode, a PEC detector was subsequently assembled. Under 365 nm illumination at zero bias, the device exhibited reproducible photocurrent switching and a response with nearly linear dependence on light intensity over the range of 13.2–105.1 mW/cm 2 . Under weak illumination, a maximum responsivity of 4.60 × 10 –5 A/W and an external quantum efficiency of 0.0157% were obtained, whereas the photo-to-dark current ratio reached 21.97 at 105.1 mW/cm 2 . Furthermore, the detector exhibited fast temporal response, with rise and decay times of 43 and 49 ms, respectively. These results demonstrate that the nanostructure organization induced by solvents provides a relatively simple route for fabricating V 2 O 5 PEC detectors with fast response and operation at zero bias. This work highlights the potential of ethanol-derived V 2 O 5 nanowire bundles for self-powered UV photodetection, particularly in terms of fast response, zero-bias operation, and high sensitivity under weak illumination.