Study On The Preparation Of BaTiO₃nanofiber Based Hybrid Materials And Their Photocatalytic Properties

In the face of the increasingly severe energy crisis and environmental pollution,the development of clean and renewable energy and the search for efficient degradation of organic pollutants has become a research hotspot.BaTiO₃is a typical perovskite-type semiconductor with good electronic properties,strong stability and high photocatalytic efficiency,and is considered as a promising photocatalyst.However,its wide band gap,low light absorption capacity,and high recombination efficiency of charge carriers limit the application of BaTiO₃in photocatalysis.In this paper,a series of optimization strategy,such as double-cocatalyst modification and S-scheme heterojunction construction,were applied to enhance the carrier separation efficiency of BaTiO₃.Moreover,due to the piezoelectric property of BaTiO₃,its photocatalytic performance is further improved by the synergistic effect of heterojunction and piezoelectric effects.Considering the unique properties of 1D nanostructures,a series of BaTiO₃-based nanofiber composite photocatalysts were designed and prepared.The morphology,structure and properties of these composites were investigated in detail to elucidate the interfacial charge transfer and performance enhancement mechanisms through various characterization techniques and DFT theoretical calculations.The details are as follows:（1）The BaTiO₃/Pt/Ni S hybrid photocatalyst was prepared by electrospinning,hydrothermal and photodeposition.The structure,morphology and surface chemical state of the composite photocatalyst were studied by various characterization techniques.The performance of these composites was evaluated by the photocatalytic hydrogen evolution.It was found that the activity of BaTiO₃/Pt/Ni S composites was significantly enhanced.This is mainly attributed to the formation of Schottky junctions between BaTiO₃and Pt,which can rapidly transfer electrons,and the formation of p-n junctions between BaTiO₃and Ni S,which can effectively capture holes in the photocatalytic reaction,thus significantly accelerating charge migration and effectively reducing electron-hole recombination.（2）Photocatalytic hydrogen evolution coupled with photodegradation of organic pollutant was explored,as additional organic sacrificial agents are commonly consumed in photocatalytic hydrogen evolution.A series of BaTiO₃/Ag₂S S-scheme heterojunction photocatalyst prepared by electrospinning and hydrothermal method were used to photocatalytic hydrogen evolution coupled with the tetracycline（TC）photodegradation.The results show that the performance of BaTiO₃/Ag₂S S heterojunction photocatalyst is obviously improved in comparison with pure BaTiO₃.This may be attributed to the S-scheme charge transfer mechanism,which improves the light absorption as well as the efficient separation of photogenerated charge carriers with strong redox capacity.The mechanism of the photocatalytic hydrogen evolution coupled with the TC photodegradation was described in detail based on the free radical capture experiments.The results showed that h⁺and e^-were used for pollutant degradation and hydrogen production simultaneously.（3）Considering the synergistic effect of S-scheme heterojunction and piezoelectric effects,the BaTiO₃/Zn In₂S₄S-scheme heterojunction photocatalyst was prepared by electrospinning and hydrothermal method.The performance of photocatalytic degradation,piezoelectric degradation,and piezoelectric photocatalytic degradation of organic pollutants were examined for the as-prepared samples.The BaTiO₃/Zn In₂S₄hybrids were found to show excellent piezoelectric photocatalytic degradation activities.The hydroxyl radical（·OH）and superoxide radical（·O₂^-）are confirmed to be the important active substances in the piezoelectric photocatalytic degradation of organic pollutants.A mechanism for piezoelectric photocatalytic degradation of organic pollutants for composite materials was proposed.