Preparation Of Copper/Graphene Composites And Their Catalytic Properties

Copper/graphene（Cu/Gr）composites have excellent mechanical properties,high electrical and thermal conductivity,as well as good oxidation and corrosion resistance to make them of great potential application in modern electronic materials,aerospace materials,construction materials and other fields.However,its research is still in the laboratory stage,and there are problems such as complicated preparation process,easy agglomeration of graphene and easy destruction of structure.In this paper,graphene（Gr）was used as the raw material to obtain uniformly dispersed graphene dispersion intermediates,and then Cu/Gr composites were successfully prepared by primary hydrothermal method,and further a new technology of preparing Cu/Gr composites by electroplating method was successfully developed for the first time.Cu/Gr composites as catalysts were applied to phenol hydroxylation with better tatalytic teactivity.The main research results are as follows:（1）A technique was developed for the preparation of Cu/Gr composites by hydrothermal method using Gr and copper acetate（C₄H₆Cu O₄·H₂O）as raw materials.The effects of reductant dosage,hydrothermal temperature,hydrothermal time and solution p H on the copper content in the composites were investigated.The optimal reaction conditions were:reducing agent dosage:Cu²⁺to ascorbic acid（VC）mass ratio of 1:2,hydrothermal reaction temperature:120°C,hydrothermal reaction time:8 h,reaction solution p H:11.The Gr structure in the composites was even dispersed,and no other impurities such as copper oxide and cuprous oxide were detected.（2）A technique was developed for the preparation of Cu/Gr composites by electroplating method using Gr as raw material.The effects of electrolyte concentration,electrode sheet distance,current magnitude and plating time on the copper content in the composites were investigated.The electroplating parametres had an effect on the Cu content in the composites,and Cu/Gr composites with different Cu contents can be obtained by controlling the electroplating reaction parameters to meet the specific application requirements.（3）The catalytic activity of phenol hydroxylation with Cu/Gr composites prepared by hydrothermal and electroplating methods was evaluated.The effects of different reaction conditions on the catalytic activity of the Cu/Gr composites were investigated using hydrogen peroxide（H₂O₂）as the oxidant.The optimum reaction conditions were obtained:phenol concentration of 5.0 wt.%,molar ratio of phenol/H₂O₂ of 1:2,reaction temperature of 70°C,reaction time of 3 h,and catalyst dosage of 0.15 g.Under the optimal reaction conditions of,the Cu/Gr composites prepared by hydrothermal method achieved 85.1%phenol conversion and 98.4%total selectivity to hydroquinone with the molar ratio of catechol to hydroquinone was 3:2.The catalyst can be reused five times without obvious activity loss,and the phenol conversion can still reach 80.5%;the Cu/Gr composites prepared by electroplating method showed 86.2%phenol conversion and 99.0%total selectivity of hydroquinone,with 3:2 molar ratio of catechol to hydroquinone.83.8%phenol conversion was achieved after five times of reuse of the catalyst.It was shown that the Cu/Gr composites prepared by both methods have good catalytic performance,with the composite prepared by electroplating method having higher activity and stability.