Block copolymer-templated gasochromic WO3 thin films with uniform mesopores for fast optical hydrogen sensing

Abstract

A method to prepare mesoporous WO3 thin films (represented by MP-WO3) with a uniform pore size of ∼18 nm is developed successfully by utilizing poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as the structure-directing agent (SDA). The properties of the gasochromic MP-WO3 thin film are studied in detail and compared with the control groups prepared by using homopolymer PEO, PS, or their mixtures as SDA. Utilizing an optimized thermal treatment procedure, the gasochromic MP-WO3 thin film of which the transmittance change ΔT is 59.1% exhibites the fastest coloration and bleaching speed with a coloration time of 27.3 s and a bleaching time of 19.7s as well as excellent reversibility within 90 cycles. This study offers a new strategy and insight into the development of mesoporous WO3 hydrogen gasochromic films with excellent performances and paves its way toward the application of an optical hydrogen sensor.