Synthesis And Enhanced Photocatalytic Performance Of CaTiO₃ Nanocuboids

In this thesis,calcium titanate?CaTiO₃?is used as the main research body.CaTiO₃nanocuboids?CaTiO₃ NCs?were prepared by hydrothermal method,which were respectively treated with NaBH₄ surface treatment,Au nanoparticles?Au NPs?surface modification,and Ag₂S quantum dots?Ag₂S QDs?form a binary Z-type heterojunction and form a ternary Z-type heterojunction with AgBr/g-C₃N₄ to enhance the photocatalytic performance of CaTiO₃ NCs.Rhodamine B?RhB?is used as the model pollutant.The photocatalytic enhancement effect of the four modification methods is compared and analyzed to find the best treatment method.I particularly hope that this thesis can serve as a reference for the treatment of environmental pollution in real life.The specific research contents are as follows:1.Using P25 as a titanium source,CaTiO₃ NCs?width:0.3-0.5?m,length:0.8-1.1?m?were synthesized by hydrothermal method and the growth process was systematically studied.The photocatalytic activity of CaTiO₃ NCs under simulated sunlight is significantly higher than that of CaTiO₃ nanoparticles?⁵5 nm?prepared by sol-gel method.This is due to the special exposed surfaces?010?and?101?of CaTiO₃ NCs.2.Treating CaTiO₃ NCs with NaBH₄ to enhance their photocatalytic performance.The results of photocatalysis experiments show that R0.1 M-CaTiO₃ exhibits the best photocatalytic activity,and its photocatalytic activity under simulated sunlight is twice that of CaTiO₃ NCs,which is mainly attributed to two factors:?1?Using NaBH₄treat CaTiO₃ NCs,the formed surface disorder expands the light absorption area.?2?The disordered surface states can act as electron acceptors to capture photogenerated electrons,effectively inhibiting the recombination of photogenerated electron-hole pairs,and prompting more photogenerated holes to participate in the photocatalytic reaction.3.Assemble Au NPs with a size of 3-7 nm on the surface of CaTiO₃ NCs.4.3%Au@CaTiO₃ showed the best photocatalytic performance,and its photocatalytic activity under simulated sunlight was 3.9 times that of CaTiO₃ NCs.The main reasons are:?1?Au NPs act as electron acceptors for CaTiO₃ NCs,thereby effectively hindering the recombination of photogenerated electron-hole pairs in CaTiO₃ NCs;?2?The electromagnetic field caused by local surface plasmon resonance?LSPR?effect of Au NPs can can promote the generation and separation of electron-hole pairs in CaTiO₃NCs;?3?The LSPR effect induces the electrons generated in Au NPs to participate in the photocatalytic reaction.4.Assemble Ag₂S QDs?7-17 nm?onto CaTiO₃ NCs,aiming to construct an Ag₂S@CaTiO₃ direct Z-type heterojunction photocatalyst with excellent photocatalytic performance.15%Ag₂S@CaTiO₃ as the best composite ratio,the photocatalytic activity under ultraviolet light is about 3.6 times that of CaTiO₃ NCs,which can be explained by the effective separation of photogenerated electron-hole pairs caused by Z-type carrier transfer.In addition,all composite materials exhibit enhanced visible light photocatalytic performance.5.A new ternary CaTiO₃/g-C₃N₄/AgBr Z-type heterojunction photocatalyst was studied by assembling g-C₃N₄ nanoplates and AgBr nanoparticles on the surface of CaTiO₃ NCs.The photocatalysis experiment showed that the best composite ratio was CaTiO₃/10%g-C₃N₄/50%AgBr,and its photocatalytic activity was 28.3,19.9 and 2.0times that of CaTiO₃ NCs,g-C₃N₄ and AgBr,respectively.The Z-type carrier transfer mechanism enables the effective separation of photogenerated electron-hole pairs to explain the enhanced photocatalytic performance of the ternary CaTiO₃/g-C₃N₄/AgBr composite.