Study On Design And Preparation Of WO₃-based Photocatalysts And Their Enhanced Performance

The rapid development of human society has resulted in increasingly serious energy and environmental problems.Solar photocatalysis technology provides an effective solution to these issues by enabling the decomposition of aquatic hydrogen and the degradation of organic pollutants.This technology has shown great potential and has become a research hotspot in the field of materials and chemistry.However,existing semiconductor photocatalytic materials have several drawbacks,including low photoabsorption efficiency,easy carrier recombination,and slow surface REDOX kinetics,which lead to low photocatalytic activity.To address these issues,we focused on WO₃,which has good acid resistance,stability,and a narrow band gap of 2.6 e V.However,intrinsic WO₃ suffers from rapid recombination of photogenerated carriers and slow surface reaction rates.To improve WO₃ photocatalytic performance,we synthesized electrospun WO₃ nanofibers and zero-dimensional WO₃ quantum dots by adjusting the dimensions and morphologies of semiconductors.We employed metal heteroatomic doping and semiconductor recombination strategies to enhance the photocatalytic performance of WO₃ for degrading VOCs and decomposing aquatic hydrogen.（1）We prepared WO₃ nanofibers with uniform size by a one-step calcination method and developed a Cu-doped WO₃ nanofibers photocatalyst using a non-noble metal element doping strategy.Copper replaces W atoms on the WO₃ matrix with a pentagram,causing charge rearrangement,inducing a local electric field between Cu and WO₃ nanofibers,and promoting photogenerated charge separation.In addition,Cu dopants promote the production of·OH radicals,enhancing the photodegradation of VOCs.Our studies showed that 0.7%Cu-doped WO₃ nanofibers had the best photocatalytic oxidation properties for formaldehyde and acetone,which were 5.5 times and 4.8 times higher than intrinsic WO₃ nanofibers,respectively.We used XPS,photoelectric tests,EPR spectroscopy,and DFT calculations to confirm the electron transfer and catalytic reaction mechanism of the catalyst.（2）We also synthesized 0D WO₃ quantum dots by a hydrothermal method and combined them with 3D In₂S₃ micron flowers to obtain 3D/0D In₂S₃/WO₃ S-scheme photocatalyst.We used SEM to observe the special fractional structure of In₂S₃ micron flowers and calculated the specific surface area of In₂S₃ micron flowers using a nitrogen adsorption desorption apparatus.Combined with XPS and element distribution,we observed that In₂S₃microflowers and WO₃quantum dots could be stably coupled together and self-assembled to construct In₂S₃/WO₃composite photocatalyst.We then studied the electron transfer mechanism of the S-type heterojunction of the composite photocatalyst using XPS tests combined with DFT and confirmed that the composite catalyst retained the strong REDOX ability of the intrinsic photocatalyst using EPR tests.The photocatalytic water analytic hydrogen activity test and the photocatalytic nitrobenzene hydrogenation experiment confirmed that the S-type heterojunction photocatalyst significantly improved the photocatalytic activity.