Optical H2-sensing properties of ordered porous WO3 films prepared by colloidal template method

In the coming hydrogen energy era, the development of optical WO3 hydrogen sensor with fast response speed provides a new method to detect hydrogen gas. In this work, the ordered porous WO3 films with different pore sizes were prepared by colloidal template method, and catalyst Pt was loaded by sputtering method. The Pt/WO3 films exhibited uniform and ordered porous structure with average pore diameter of 325, 772, and 1119 nm, respectively, and Pt particle size is 3 similar to 4 nm. Comparing the transmittance signal and reflectance signal during the gasochromic process to 4% H-2 gas, the change of transmittance signal is significantly (Delta T-1500nm is 9.5 similar to 28.6%), while the reflectance signal is basically unchanged (Delta R-1500nm < 2%). Comparing Pt/WO3 films with different structures or pore sizes, it was found that the 325 nm porous Pt/WO3 film shows the fastest coloring response speed of 66.3 s to 4% H-2 gas, four times faster than 1119 nm porous Pt/WO3 film (246.4 s), and six times faster than dense Pt/WO3 film(411.5 s). The 325 nm porous Pt/WO3 film can maintain a fast response speed after 100 coloring-bleaching cycles, and show different transmittance change value to different concentrations of H-2 gas. This study offers a new strategy for the design of optical sensors with high performance based on WO3 film.