Preparation And Properties Of Activated Carbon Fiber Supported Metal Oxide Composites

At present,the synthesis processes of metal oxide photocatalysts such as Cu₂O,ZnO and BiOCl have become increasingly mature,but the application of powdered catalysts has a common problem.Firstly,the microscopic particles of the metal oxide are prone to agglomeration during the preparation process,resulting in a decrease in the separation efficiency of the photogenerated electron-hole,and a shortened service life of the photocatalyst;then the semiconductor catalyst existing in the form of powder is easily lost,and it is difficult to separate and recover.Therefore,it is necessary to seek reliable carriers,substrates or carriers to solve the problem of fixing and separating photocatalysts.Activated carbon fiber?ACF?is one of the more compelling supports in recent years.ACF can not only effectively increase the specific surface area of the catalyst,but also improve the light utilization efficiency and inhibit the photoelectron-hole recombination.In addition,due to the interaction between the metal oxide and the carbon material,the composite material has higher photocatalytic stability than the pure metal oxide.In this paper,Cu₂O/ACF,ZnO/ACF and BiOCl/ACF composites were prepared,and the structure,morphology and catalytic properties of the materials were studied.The main research contents are summarized as follows:1.Using ACF as the carrier,Cu?NO₃?₂·3H₂O as the copper source,thylene glycol as the solvent and reductant,the cubic Cu₂O particles were deposited on the surface of ACF by polyol reduction method.The effects of different reaction temperatures on the structure,morphology and photocatalytic properties of the composites were investigated,and the growth mechanism of Cu₂O on ACF was proposed.The results show that the sample prepared at the reaction temperature of 170°C has better adsorption performance than ACF cloth,and the adsorption efficiency can reach 89.4%after 24 h.The same sample has the best photocatalytic activity and the degradation efficiency after 6 h can reach 86.1%,and its efficiency remained at about 80%after 5 cycles of degradation experiments.We propose a photocatalytic mechanism of visible light-driven Cu₂O/ACF composites:composites exhibit enhanced photocatalytic activity due to the synergistic effect between the strong adsorption of ACF and the photocatalytic activity of Cu₂O.2.The ACF was acidified with 15%nitric acid,then the ZnO/ACF composite was prepared by the impregnation-hydrothermal method using acidified ACF as the carrier and cetyltrimethylammonium bromide?CTAB?as the surfactant.The effects of CTAB addition and hydrothermal reaction time on the adsorption and photocatalytic activity of the composites were researched.The results indicated that the structure and morphology of ACF did not change before and after acidification,and a large number of oxidized groups were attached to the surface of ACF after modification.When the amount of CTAB added in the growth solution is 2.0 mM,the ZnO/ACF composite has the best adsorption performance and photocatalytic activity for the MO solution.The adsorption rate of the sample reaches95.6%after 5 h,the photocatalytic degradation experiment of the sample was carried out under the visible light,and the degradation efficiency reached 99.4%after 5 h.The hydrothermal reaction time has little effect on the properties of ZnO/ACF composites.In addition,the growth mechanism of ZnO on the surface of ACF can be explained by electrostatic attraction.3.The BiOCl/ACF composites were successfully prepared by solvothermal method using NaCl as the Cl source and citric acid?AC?as the structure directing agent.The effects of different citric acid dosages on the phase structure,morphology and photocatalytic activity of BiOCl/ACF composites were discussed.The results demonstrate that BiOCl on the surface of ACF is assembled from ultra-thin nanosheets.The photocatalytic performance of the composite under the visible light was investigated by measuring the degradation of Rh-B solution.It was found that BiOCl/ACF composites have higher photocatalytic degradation efficiency than pure BiOCl.The sample prepared with an AC dosage of 2.800 g has the best photocatalytic performance,and the degradation efficiency reaches 99.5%after180 minutes of irradiation.The excellent photocatalytic properties of composite materials are due to the formation of photosensitizers between dye molecules and BiOCl.