Space-Confinement Epitaxy of Single-Crystalline V2O5 Nanowire Arrays for High-Performance and Flexible Hydrogen Sensing.

Oxide nanostructures hold great promise for next-generation gas-sensing technologies owing to their chemical stability, rich surface chemistry, and tunable electronic properties. However, controlled epitaxial growth of oxide nanostructures remains challenging, particularly for V2O5, a highly promising material for hydrogen detection. Here, we develop a space-confinement chemical vapor deposition strategy that enables epitaxial growth of highly ordered V2O5 nanowire arrays on r-Al2O3 substrates. The confined geometry precisely regulates gas-phase transport and surface reaction kinetics, allowing morphology control via confinement distance and yielding single-crystalline nanowires with atomically sharp interfaces. Upon Pd decoration, V2O5 nanowire array sensors demonstrate remarkable hydrogen-sensing performance, featuring high sensitivity, low optimal operating temperatures down to room temperature, and rapid response/recovery dynamics. Moreover, flexible single-nanowire sensors maintain stable performance under repeated mechanical deformation. This work provides fundamental insight into space-confinement epitaxy of nanostructures and establishes a scalable route toward flexible, low-power, and high-performance gas sensors for future wearable and intelligent environmental monitoring technologies.