Synthesis of monoclinic WO3 nanosphere hydrogen gasochromic film via a sol–gel approach using PS-b-PAA diblock copolymer as template

A monoclinic tungsten trioxide (WO3) nanosphere film was synthesized via a sol–gel approach using an amphiphilic diblock copolymer polystyrene-b-polyacrylic acid (PS-b-PAA) as template in toluene. The morphology, surface area and crystal structure of as-synthesized WO3 were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), BET (N2) and powder X-ray diffraction (XRD). The XRD pattern of WO3 nanosphere film can be identified as a pure monoclinic WO3 phase. The WO3 precursor nanospheres had diameters ranging from 20 to 150 nm and surface area of 78.8 m2 g−1. The hydrogen gasochromic experiments revealed that such WO3 nanosphere film with high surface area had a rapid response (5 ∼ 10 s) to pure hydrogen at room temperature.

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