Study On Photocatalysis And Energy Storage Ability Of Pt-loaded And Hydrogen-treated WO₃

With the industrial development, the problem of the environmental pollution isgetting worse. Especially the indoor air pollution, with major pollutants such asformaldehyde, is a serious threat to people’s health. Photocatalytic semiconductormaterials excitated by light can effectively break down and mineralize pollutants,converting light energy into chemical energy. With the advantage of the fast, non-selectiveoxidation with full depth of the pollutants, photocatalysis is considered to be an effectivesolution to this problem. But traditional photocatalytic materials due to the large band gap,the high recombination rate of the photogenerated carriers and other issues, suffer fromproblems such as the low solar energy utilization efficiency and the low conversionefficiency. Besides, it can only work in the light, which greatly limits its practicalapplication. And it is found that the material modification, the hydrotreatment and theplatinum loading, can respectively expand the absorption spectrum and inhibit therecombination of photoexcited carriers, thereby improving the photocatalytic activity ofthe materials; photocatalytic energy storage material systems can make the photocatalyststate continue to play its role in the dark, by storing the energy absorbed in the light.Therefore, in this work, the photocatalytic material WO3, which can also be used asthe energy storage material, was hydrogenated and platinum loaded, to study itsphotocatalytic degradation of formaldehyde performance, energy storage properties andphotoconductive properties. It is found that the absorption spectrum of thehydrogen-treated WO3extended to infrared region, and its visible-infrared light absorptionwas higher than ultraviolet light, but either in the light or in dark no degradationperformance of formaldehyde was shown; platinum loading of WO3did not get extendedabsorption spectrum, though the photocatalytic activity was enhanced, and showed shortenergy storage performance. Modified with a combination of both ways, thehydrogen-treated and Pt-loaded WO3, showed both the infrared light absorbing properties,and the further enhanced photocatalytic activity. In addition, it showed a super-longpersistent energy storage ability, with the degradation performance of formaldehyde after stored in dark for300h. The photoconductive test results further confirmed the results ofthe catalytic experiments.Furthermore, in this work, a number of means like XRD, SEM, Raman, HRTEM, PLspectra, XPS, NMR, UV-vis absorption spectroscopy was applied to characterize thestructure of the platinum loaded and hydrogenated samples. The photocatalytic and energystorage mechanism of the platinum-loaded and hydrogen-treated WO3was also discussed.