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

One-dimensional V2O5 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 V2O5 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 V2O5 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 V3O7·H2O precursor, which was subsequently converted into orthorhombic V2O5 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 V2O5 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/cm2. 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/cm2. 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 V2O5 PEC detectors with fast response and operation at zero bias. This work highlights the potential of ethanol-derived V2O5 nanowire bundles for self-powered UV photodetection, particularly in terms of fast response, zero-bias operation, and high sensitivity under weak illumination.