Exploration of the use of p-TeO₂-branch/n-SnO₂ core nanowires nanocomposites for gas sensing

Branched nanowires (NWs) are a novel class of composite materials with increased surface area relative to their pristine one-dimensional counterparts. Accordingly, they are good choice for gas sensing studies. In this study, p-n, TeO₂-branched SnO₂ NWs were produced by a two-step catalyst-assisted vapor-liquid-solid (VLS) growth technique for gas sensing studies. First, SnO₂ NWs were synthesized from highly pure Sn powders, and TeO₂ branches were subsequently added. The fabricated samples were well characterized in terms of morphology, crystallinity, and chemical composition. Gas sensing results exhibited the enhanced NO₂ sensing capability of TeO₂ branched SnO₂ NW sensors relative to pristine SnO₂ NWs. In particular, the maximum responses (R_g/R_a) of pristine and TeO₂ branched SnO₂ sensors to 10 ppm NO₂ were 6.34 and 10.25, respectively. Furthermore, dynamics of TeO₂ branched sensor at the optimal temperature was faster. Superior sensing properties of TeO₂ branched SnO₂ NWs were related to the high surface area of the branched sensors and creation of p-n heterojunctions on the surfaces of this sensor. We believe that branching is a good way to realize gas sensors for practical usages.