PDA and its derived NGC membrane coated A-TiO2 for visible-light-driven photocatalytic oxidation of acetaldehyde
In order to improve the catalytic degradation performance of TiO2 for continuous flowing acetaldehyde under visible light irradiation,core-shell type anatase TiO2(AT)(AT@P and AT@C)wrapped by a broad-spectrum polydopamine(PDA)and its derived N-doped carbon(NGC)membrane were constructed using mussel bionic chemistry strategy and high-temperature carbonization process.Scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),UV-visible diffuse reflection spectroscopy(UV-vis DRS),instantaneous photocurrent density-time curve(I-t)and A.C.impedance(EIS)were used to characterize the physicochemical and photoelectric properties of the materials.The effects of different coating amounts of PDA and the microscopic compositional and structural changes before and after carbonization at optimal coating amount on the visible light-driven catalytic performance of acetaldehyde were studied.The results showed that PDA coating significantly enhanced the visible light absorption and photo-induced carrier separation ability of AT,leading to a significant improvement of photocatalytic degradation activity of acetaldehyde under visible light irradiation.When the addition of DA was 50 mg,the degradation efficiency of acetaldehyde over AT@P-50(71％)was higher than that of AT@P-10 and AT@P-100,which was 2.09 times of that of AT.The conversion of highly active N(graphitized N)with π-conjugate structures can further improved carrier separation efficiency and interfacial mobility of materials,thus promoting the photocatalytic activity and stability of AT.The degradation rate of AT@C-50 coated with NGC derived from the PDA with optimum amount is up to 77％,which is 2.26 and 1.08 times of AT and AT@P-50,respectively.Under the same continuous flowing system and acetaldehyde concentration conditions,the synthesized AT@P-x(x=10,50 and 100)and AT@C-50 exhibited superior visible photocatalytic degradation of acetaldehyde compared to other well-designed TiO2 composites.In addition,In-situ infrared diffuse reflectance technique(in-situ DRIFTS)is used to investigate the evolutionary behavior of the intermediate products of AT@C-50 with optimal catalytic performance in the acetaldehyde catalytic process,and the possible catalytic pathways and reaction mechanisms were revealed.
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