Preparation And Photoelectrocatalysis Properties Of C-doped SnO₂

Tin dioxide（SnO₂）, which crystallizes in tetragonal, hexagonal or orthorhombic structure, is a kind of N-type semiconductor metal oxide. It is a candidate material for the electronic components and the sensors. However, its application in the field of photoelectric catalysis is limited for the wider band gap of the SnO₂（Eg= 3.6 e V,T =300 K）. Therefore, how to improve the photoelectric catalysis efficiency and the value of photoelectric chemical response of SnO₂ becomes a hot topic in the photocatalytic fields.Photoelectrocatalytic performance of semiconductor can be improved through doping non-metal material. In this work, using the Sn Cl2.2H2 O as raw material, DMF as solvent, and CH3NH3 I as carbon doping source, we prepared C-doped SnO₂ powder by the solvent thermal method. The structure and morphology of C-doped SnO₂ were investigated by scanning electron microscope（SEM）, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）. The photoelectrocatalytic water splitting and photocatalytic degradation of methyl orange and phenol of C-doped SnO₂ and SnO₂ were studied under simulated sunlight, respectively. According to the analysis of the experimental data, results are as follow:（1） The size of C-doped SnO₂ prepared by the solvent thermal method is 100 nm. The optimal technological parameter is 150 oC, 15 h, DMF. C-doped SnO₂ had the highest photocurrent value（0.5013 m A/cm2）at 150 oC,on 15 h and in DMF. The process of the preparation of C-doped SnO₂, which is energy-saving and environment-friendly, has certain reference significance for the synthesis of SnO₂.（2） XPS illustrated that the C element replace lattice oxygen of SnO₂, which increased the oxygen vacancy concentration; Plane-sweep EDS showed the C element in the C-doped SnO₂ was distributed uniformly without obvious stratification; The Sn Cl2 and CH3NH3 I diffraction peak were absent in XRD spectrum, which indicated the reactants in reaction process were almost transformed into the target product; XRD diffraction peak of C-doped SnO₂ had a good agreement with the basic standard of the SnO₂ diffraction peak; Uv-vis absorption spectroscopy of C-doped SnO₂ showed obviously red shift, which indicated that increase the absorption in visible spectral range.（3） The experimental results showed that photocurrent of the C-doped SnO₂ photoanode under the simulated sunlight irradiation（AM 1.5G） could reach 0.15 m A/cm2 at 0 V vs Ag/Ag Cl, which was two orders of magnitude higher than that of SnO₂ prepared by direct oxidation（<2×10-3 m A/cm2）.（4） In the experiment of the photocatalytic degradation of methyl orange and phenol, we found that the degradation rate of C-doped SnO₂ photocatalytic materials was 3 times higher than that of pure SnO₂ powder; The photocatalytic degradation circulation experiments of C-doped SnO₂ materials showed that it had a better cyclic performance. In the photoelectrocatalytic water splitting experiment of the C-doped SnO₂ photoanode, the hydrogen production rate of C-doped SnO₂ was 7.08 μmol/h?cm2 under the simulated sunlight irradiation.