Preparation And Properties Of Bi-based Piezoelectric Photocatalytic With Different Morphologies

With the rapid development of industrialization,the discharge of hard-to-degrade organic pollutants poses a potential threat to the water environment.Photocatalysis as an environmentally friendly and efficient treatment technology has been widely used in the treatment of water environment.However,the photogenerated carrier compounding problem greatly limits the development of conventional photocatalysis.To solve this problem,this study utilizes the coupling effect of photocatalysis and piezoelectric effect,and uses the piezoelectric potential generated by the deformation of piezoelectric materials as a driving force to suppress the compounding of photogenerated electron holes and improve the degradation efficiency of photocatalysis.It is worth noting that the morphology of piezoelectric materials plays an important role in the performance of piezoelectric photocatalytic,but the study of the specific mechanism of action is still lacking.Therefore,in this study,high-performance Bi-based piezoelectric photocatalytic materials Ti-Bi OCl and Bi_3.25La_0.75Ti₃O₁₂（BLT）with different microscopic morphologies were prepared by modulating the synthesis process.The degradation of composite organic pollution by two different dimensions of Ti-Bi OCl（nanowires,nanosheets）and three different dimensions of BLT（nanowires,nanosheets,nanospheres）were compared and analyzed,and the influence of microscopic morphology on the catalytic performance of piezoelectric photocatalysts was deeply explored by combining ESR,electrochemical analysis,PFM,FEM and other characterization means,which provides a new piezoelectric photocatalytic material design of new piezoelectric photocatalytic materials,which provides useful guidance.The results of the study are as follows:（1）Two dimensions of Ti-BiOCl were used as the study models,and rhodamine B（Rh B）and tetracycline（TC）were used as the target composite contaminants to investigate the effect of micro-morphology on the catalytic performance of piezoelectric photocatalytic materials.Well-grown Ti-Bi OCl nanowires and nanosheet piezoelectric photocatalysts were obtained by regulating the synthesis temperature under the premise of optimal Ti doping ratio（Ti:Bi=1:4）and optimal p H of the synthesis solution（p H=9）.When the temperature was250℃,Ti-Bi OCl was a one-dimensional nanowire structure;when the synthesis temperature was 180℃,Ti-Bi OCl exhibited a two-dimensional nanosheet structure.The degradation of Rh B and TC by Ti-Bi OCl with different morphologies shows that in the presence of both light and ultrasound,Ti-Bi OCl nanowires exhibited better voltage-pressure photocatalytic performance than nanosheets,and the degradation rates of Rh B and TC could reach 99.01%and 93.97%after 60 min and 10 min,respectively,corresponding to the reaction rate constants of 0.070 min^-1 and 0.318 min^-1,respectively.（2）Three different dimensions of BLT were used as the study models,and 2,4-dichlorophenol（2,4-DCP）and tetracycline（TC）were used as the target composite contaminants to investigate the effect of micro-morphology on the piezoelectric photocatalytic performance in a more comprehensive and in-depth manner.Well-grown BLT nanowires,nanosheets and nanospheres piezoelectric photocatalysts were obtained by regulating the synthesis temperature under the premise of optimal p H of the synthesis solution（p H=9）.When the temperature was 250℃,BLT exhibited a one-dimensional nanowire structure;when the temperature was 180℃,BLT was a two-dimensional nanosheet structure;when the synthesis temperature was 80℃,BLT was a three-dimensional nanosphere structure.The degradation of 2,4-DCP and TC by BLT with different morphologies shows that in the presence of both light and ultrasound,BLT nanowires exhibit the best catalytic performance,followed by BLT nanosheets,and BLT nanospheres have the worst catalytic effect.The degradation rates of 2,4-DCP and TC by BLT nanowires were up to 93.04%and 96.30%after 60 min and 8 min,respectively,corresponding to the reaction rate constants of 0.042 min^-1 and 0.428 min^-1,respectively.（3）The Bi-based catalysts showed different degradation effects on organic pollutants under different conditions,among which,the best results were obtained in the presence of both light and ultrasound,which indicates that the introduction of ultrasound has a positive contribution to the photocatalytic degradation process.The ESR characterization results show that the strongest intensities of the signals of·OH and·O₂^-are generated in the catalyst system in the presence of both light and ultrasound,which proves that the catalyst can generate more reactive radicals in the system in the presence of both light and ultrasound.The results of photoelectrochemical tests such as EIS and photocurrent response can be concluded that in the presence of both light and ultrasound,the system resistance decreases significantly and the intensity of photocurrent generated by the increased amount of photogenerated charge is enhanced.It can be proved that the introduction of ultrasound makes the photogenerated electron and hole complexes effectively suppressed,which finally shows the improvement of the pollutant degradation effect.（4）Bi-based catalysts with different micro-morphologies showed different degradation effects on organic pollutants,among which,low-dimensional materials showed the most excellent piezoelectric photocatalytic performance,specifically 1D materials were better than 2D materials（better than 3D materials）.PFM,FEM and other characterization results demonstrate that the one-dimensional piezoelectric photocatalyst can generate a larger piezoelectric potential under the same external force compared to the two-dimensional（three-dimensional）.The ESR characterization results show that the strongest intensity of·OH and·O₂^-signals are generated in the one-dimensional piezoelectric photocatalyst system in the presence of both light and ultrasound,which indicates that the larger piezoelectric potential generated by the low-dimensional piezoelectric photocatalyst is more favorable to inhibit the complexation of photogenerated carriers,thus allowing more reactive radicals to participate in the degradation of organic pollutants.It is thus clear that microscopic morphology plays a decisive role in the catalytic performance of piezoelectric photocatalysts.