Nanoscale Pd catalysts decorated WO₃–SnO₂ heterojunction nanotubes for highly sensitive and selective acetone sensing

In this study, we report on the construction of multiple heterojunctions by functionalization of WO₃–SnO₂ n–n junction nanotubes (NTs) with nanoscale Pd catalysts for highly sensitive and selective acetone sensing. WO₃–SnO₂ n–n junction NTs with various W/Sn molar ratios were fabricated via an electrospinning technique. Pd decoration of WO₃–SnO₂ NTs was further developed by a chemical deposition method. As a result, the enhancement of sensing selectivity and sensitivity to acetone and reduction of operating temperature were simultaneously achieved. The enhanced sensing characteristics of Pd@WO₃–SnO₂ NTs were mainly ascribed to the formation of multiple heterojunctions (WO₃–SnO₂ n–n junctions, PdO–SnO₂ and PdO–WO₃ p–n junctions) and chemical sensitization effect of Pd nanocatalysts. The present results demonstrate that porous WO₃–SnO₂ heterojunction NTs decorated with nanoscale Pd catalysts have a good potential for sensitive and selective detection of acetone.