Confined interfacial micelle aggregating assembly of ordered macro–mesoporous tungsten oxides for H2S sensing

Abstract

Porous tungsten oxides (WO₃) have been implemented in various application fields including catalysis, energy storage and conversion, and gas sensing. However, the construction of hierarchically ordered porous WO₃ nanostructures with highly crystalline frameworks remains a great challenge. Herein, a confined interfacial micelle aggregating assembly approach has been developed for the synthesis of ordered macro–mesoporous WO₃ (OMMW) nanostructures using three-dimensional SiO₂ photonic crystals (PCs) as nanoreactors for the confined assembly of tungsten precursor and poly(ethylene oxide)-block-polystyrene (PEO-b-PS) template. After the heat treatment and etching processes, the obtained OMMW could achieve hierarchically ordered porous nanostructures with close-packed spherical mesopores (∼34.1 nm), interconnected macro-cavities (∼420 nm), high accessible surface areas (∼78 m² g⁻¹), and highly crystalline frameworks owing to the protection of dual templates. When OMMW nanostructures were assembled into gas sensors for the detection of H₂S, the resulting sensors exhibited excellent comprehensive sensing performance, including a rapid response–recovery kinetics, in addition to high selectivity and long-term stability, which are significantly better than the previously reported WO₃-based sensors. This study paves a promising way toward the development of hierarchically ordered porous semiconductors with large and interconnected porous channels for sensing applications.