Abstract
The mesoporous tungsten oxides have shown great potential in various fields, including energy storage and conversion, catalysis, and gas sensor, because they have ordered porous architectures and unique semiconducting property for host-guest interaction. Most of the reported mesoporous tungsten oxides have monomodal mesopores, which are not favorable for the mass diffusion and host-guest interactions. To date, it still remains a great challenge to synthesize ordered mesoporous WO3 with bimodal or hierarchical pores and crystalline frameworks. Herein, a pore engineering strategy is demonstrated for the synthesis of ordered mesoporous WO3 with well-connected bimodal pores, and crystalline pore walls by using hydrophilic resols as the sacrificial carbon source which can interact preferentially with poly(ethylene oxide) (PEO) domains and serves a glue to bridge the tungsten species and poly(ethylene oxide)-block-polystyrene block copolymers. The obtained ordered mesoporous tungsten oxide materials possess dual mesopore size (5.8 and 15.8 nm), high surface area (128 m(2) g(-1)), large window size (7.7 nm), and highly crystalline mesostructure. The dual mesoporous WO3-based gas sensor exhibits significantly excellent gas sensing performance toward H2S with a rapid response (3 s) and recovery (14 s) even at low concentration (0.2 ppm), and high selectivity, which is much better than previously reported WO3-based sensors.