Preparation Of Ni-modified TiO₂ Nanotube Array Composites And Their CO₂ Reduction Properties

Photoelectric catalytic reduction of CO₂ technology is relatively mild in practical production with its reaction conditions and meets the requirements of green chemistry.TiO₂ NTs,with its unique and regular structure,is widely used in photoelectric catalytic reduction technology.However,due to its low selectivity and yield,the modification and morphology control of TiO₂ NTs have gradually become a research focus.Therefore,this paper takes TiO₂ NTs array as the research object,changes different preparation conditions by in situ secondary oxidation method to synthesize TiO₂ NTs array,and then compounds nickel oxide to the array surface by photoelectric deposition technology,and then studies its photoelectric performance and photoelectric catalytic reduction performance,and obtains the following research results:Using photoelectric deposition technology by changing the sequence of sedimentary and roasting and photoelectric sedimentary Ni²⁺concentration of nickel oxide compound further to TiO₂ NTs array on the surface,the results show that by first deposition of Ni TiO₂ NTs array reduces the original TiO₂ NTs array forbidden band width,forbidden band width value reduced from 3.2 eV to 2.08 eV,greatly improve the optical performance.CO₂ was reduced by means of optical,electrical and magnetic field coupling,and the reduced products were detected and analyzed by gas and liquid chromatography.The results show that formic acid has the highest selectivity under the condition of pure light,and the selectivity is more than 99%,while formaldehyde and methanol have the lowest selectivity,which is less than 1%.Under the ultraviolet light,the reduction voltage of-0.75 V and the electromagnetic field of 5 V,the three fields catalyzed the reduction reaction of NiO-TiO₂ NTs array material with the concentration of Ni²⁺0.1mol L^-1.The highest space-time rate of product formic acid was 53243.76 nmol?h^-1?cm^-2,the highest space-time rate of formaldehyde was13807.59 nmol?h^-1?cm^-2,and the highest space-time rate of methanol was 2783.75nmol?h^-1?cm^-2.The selectivity of formaldehyde and methanol was increased to 19.77%and 3.99%respectively,which was more conducive to the production of formaldehyde and methanol,two difficult reduction products.