Space‐Confinement Epitaxy of Single‐Crystalline V 2 O 5 Nanowire Arrays for High‐Performance and Flexible Hydrogen Sensing

ABSTRACT 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 V 2 O 5 , a highly promising material for hydrogen detection. Here, we develop a space‐confinement chemical vapor deposition strategy that enables epitaxial growth of highly ordered V 2 O 5 nanowire arrays on r‐Al 2 O 3 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, V 2 O 5 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.