Optical Absorption And Photocatalytic Properties Of ?Au,Ag,Cu?/BaTiO₃ Composite Thin Films

Metal nanoparticles?NPs?dispersed composite films can be fabricated by dispersing metal NPs into suitable semiconductors.The optical absorption band can be broadened by the surface plasmon resonance?SPR?and interband transition of metal NPs,thus resulting in the enhanced optical absorption and photocatalytic properties of semiconductors.Among all metals,Au,Ag and Cu are considered as the most effective dispersing elements since they have chemical stability,a remarkable SPR effect and interband transition.On the other hand,BaTiO₃?BTO?is an important semiconductor with rich reserves,low-cost and excellent chemical stability,however,its photocatalytic property has rarely been reported.Therefore,in the present study,?Au,Ag,Cu?/BTO composite films were studied in expect that the optical absorption of BTO can be broadened due to the SPR effect and interband transition of Au,Ag and Cu NPs,thus promoting the photocatalytic property.The optical absorption properties of?Au,Ag,Cu?/BTO composite films were theoretically caculated by classical and modified Mie theory,the effects of metal species and content on the phase structure and morphology,optical absorption and photocatalytic properties and the related mechanism were systematically inversitaged.The optical absorption spectra of the nano-composite films dispersed by Ag,Au and Cu NPs were simulated by the classical Mie theory.It was found that the optical absorption spectra exhibit SPR absorption peaks and interband transition in visible region.The optical absorption properties were theoretically caculated by classical Mie theory for Au/BTO,Ag/BTO,Cu/BTO monometallic NPs dospersed composite films mixture and by modified Mie theory for?Au,Ag?/BTO,?Ag,Cu?/BTO,?Au,Cu?/BTO bimetallic and binary alloy NPs dispersed composite films.The influences of metal content on the SPR absorption peak and interband transition were analyzed.Au/BTO,Ag/BTO and Cu/BTO composite films with amorphous BTO and cubic metallic Au,Ag and Cu NPs were fabricated by a simple sol-gel and spin-coating method.The phase structure and morphology,optical absortion and photocatalytic properties,and the enhanced mechanism of the properties were investigated.The optical absorption band ascribed to the SPR effect and interband transition of Au NPs were broadened for all the BTO based composite films,resulting in the enhanced photocatalytic properties for the degradation of rhodamine B?RhB?under UV-vis light.The degradation efficiency of the RhB on the AU35/BTO,Ag₂₅/BTO and Cu₂₅/BTO thin films is about 3,5 times higher than the pristine BTO.The photocatalytic property of Cu₂₅/BTO thin film is comparable to that of the Au₃₅/BTO and Ag₂₅/BTO films.Therefore,Cu is expected to substitute for Au and Ag to low the cost of semiconductor photocatalysts.The Ag₂₅Aux/BTO composite thin films were further prepared and their phase structure and morphology,optical absortion and photocatalytic properties,and the mechanism of the enhanced photoactivity were investigated.The cubic Au-Ag binary alloy NPs are uniformly dispersed in the amorphous BTO.The optical absorption band are broadened after the addition of Au NPs,and the Ag₂₅Au15/BTO thin film arrives in the optimal photocatalytic efficiency of 72%for the degradation of RhB,which is enhanced by 10%compared to the Ag₂₅/BTO.The improved optical absorption and photocatalytic properties of the composite films is attributed to the synergistic effect of the SPR effect of Ag NPs and the SPR effect and interband transition of Au NPs.