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Electromotive Force and Measurement in Several Systems Part 4

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Tham khảo tài liệu 'electromotive force and measurement in several systems part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Electromotive Forces in Solar Energy and Photocatalysis Photo Electromotive Forces 35 Thus the necessary factor was obtaining the nanoparticles with sizes in the range of 10 nm leading to the generation of heterostructures of the metal nanoparticles plasmon resonance in the system. As a result of processing the AFM images it was revealed that the copper nanoparticles generated in the conditions of the Cu2 reduction using sodium tetrahydroborate Fig. 9b possess spherical form and narrow particle size distribution of about 8 nm. According to Fig.9 c the generated Ag nanoparticles represent triangular nanoprisms with the average size of about 5 nm distributed in regular intervals on the TiO2 surface. Sample Photo-emf non-calcined mV Conductivity type TiO2 Ag 46 p- Tio2 cu 32 p- TiO2 non-modified 15 n- Table 6. The photoactivity characteristics of composite materials obtained using metal nanoparticles. The data implying high photoactivity of the Ag TiO2 composite are confirmed by the greatest photoresponse value of 46 mV Table 6. After UV irradiation the excited electrons move towards the TiO2 conductivity zone and holes move towards the valence zone through interface. Thus the separation of the photogenerated electron-hole pairs in a composite film is more efficient than in pure non-modified one. Hence the recombination of the photogenerated charge carriers also proceeds more efficiently and that is proved by an increase in the photoresponse value for the composites used. The use of copper and silver nanoparticles also promotes the increase in photocatalytic activity of a film Table 6 owing to larger water adsorption on the surface of a composite due to the nanoparticle surface effect Agafonov et al. 2009 which is promoted by a high concentration of the photogenerated holes whose presence is confirmed by composite conductivity type Tab.6. 12. Using template synthesis for obtaining materials with high photoactivity The analysis of literature data has shown that for .