Preparation Of New Type RGO-CNTs Composite Material And Ternary Skeleton CuAlZn Material And Its Application In Energy Field

With the increasing consumption of nonrenewable energy,the problems of energy shortage and environmental degradation are becoming more and more prominent.Finding clean and renewable energy has been focused on in the world.The preparation of new energy materials has become a cutting-edge topic of concern to the world.Graphene has significant characteristics including high specific surface area,high conductivity,good chemical stability and mechanical stability,and therefore has been widely used as a high performance supercapacitior electrode material.The electrode of hybrid perovskite solar cell is usually metal material which has the following disadvantages:the price of materials is expensive,needing the expensive experimental equipment and the experimental conditions are too strict.The graphene and carbon tube nanocomposite used as the top electrode materials of hybrid perovskite solar cell has great prospects.The high performance carbon material electrode not only can be used as the hole transport layer material,but also can be used as the top electrode.As a result,the cost and the toxicity will be relatively reduced.The climate change caused by excessive emission of CO2 and the harm caused by it have become the biggest environmental problems that human beings face in twenty-first Century.CO2 is a rich,cheap,clean,safe carbon resource.The study on the preparation of oxygen containing compounds by catalytic hydrogenation has attracted much attention in recent years.The use of CO2 can not only reduce the content of CO2 in nature,but also can be used to produce value-added chemicals.However,CO2 is a fairly stable compound,and its utilization efficiency is low.Therefore,it is the key to develop efficient catalytic materials for CO2 resource conversion.In this paper,graphene-carbon nanotube composites were prepared and their properties were discussed.They were used as flexible linear supercapacitor electrodes and perovskite solar cells top electrodes.In addition,a novel ternary skeleton catalyst was prepared and used in CO2 hydrogenation and the catalytic mechanism was also study.The main contents and conclusions of the study are as follows:Novel reduced graphene oxide and carbon nanotube(rGO/CNT)hybrid fibers were prepared using a facial low-temperature chemical reduction self-assembly with vitamin C as the reducing agent.Mechanical measurements showed that hybrid fibers with an ultimate elongation of 150%had better mechanical properties than the single rGO fiber with an ultimate elongation of 105%.Cyclic voltammetry(CV)results showed that rGO/CNTs hybrid fibers exhibited better electrochemical performance than the rGO fiber because of the larger CV curve area of the former.The volumetric specific capacitance of the rGO/CNTs electrode was 559.9 F cm-3,and its qualitative specific capacitance was 59.76 F g-1 at a high current density of 1 A g-1.Both the volumetric specific capacitance and qualitative specific capacitance of the rGO/CNTs hybrid fibers were higher than those of single rGO fibers,particularly at low sweep speed.The scanning electron microscopy and transmission electron microscopy images of the rGO/CNTs composite fiber clearly showed the rGO and CNTs co-assembly and the interconnected porous structure formation.In the hybrid nanostructure,CNTs served as a reinforced bar,and the synergic effect between rGO and CNTs led to hybrid fibers with enhanced mechanical and electrochemical performances.Then,a perovskite solar cell was prepared by using a graphene/carbon nanotube composite thin film material as a positive electrode material and a hole transport layer,TiO2 as an electron transport layer and a perovskite crystal as active layer.The photoelectric conversion efficiency of the solar cell is 0.3%.Finally,a structure-activity controllable synthesis of ternary skeletal CuAlZn catalyst for NaHCO3 hydrogenation to produce formic acid was first investigated.Several kinds of Cu alloy and/or the synthetic methods were considered and their catalytic activities for hydrogenation of NaHCO3 were discussed.The results found that skeletal CuAlZn-2.5 h catalyst exhibited great catalytic activity to afford the maximum value of 86.1%of formic acid with 6 MPa H2 at 200 ℃ for 4 h.Reusability showed skeletal CuAlZn-2.5 h could still keep high catalytic activity for at least repeat three times.The present study provides a mild,efficient and eco-friendly method for formic acid synthesis by the hydrogenation of NaHCO3 and CO2.