Preparation And Of Photocatalytic Performance For Hydrogen Production Of Cu NPs/ Graphene From Plumeria Rubra

Environmental pollution and energy depletion are two major global problems that need to be solved,which seriously restrict the development of human civilization.It is a consensus of all countries to enable to actively solve the energy crisis and environmental pollution problems and to seek clean,efficient,renewable,environmentally friendly and sustainable alternative energy sources around the world.With the advancement of science,a new solution has emerged—photocatalytic decomposition of water to produce hydrogen,transforming endless solar energy into clean hydrogen energy,which is a new energy source with research potential and far-reaching significance.In the development of photocatalytic decomposition of hydrogen produced by water,designing and synthesizing photocatalysts based on photocatalytic properties has become a major and difficult point.Through the unremitting efforts of scientists,we have achieved remarkable results in the design of photocatalysts.Nowadays,the research on the application of inorganic semiconductors and organic semiconductors in photocatalytic has been very thorough.The plasmon resonance photocatalytic by noble metals,such as Pt,Au and Ag is a hot research topic,except the cheap and easy to obtain Cu.There are only a handful of studies on photocatalysis of Cu,because when copper nanoparticles are in contact with air,they are easily oxidized to form copper oxides due to their active chemical activity,which affects the plasmon resonance effect of Cu nanoparticles.Therefore,in order to prevent oxidation and agglomeration of Cu nanoparticles,an ideal and feasible method is to load Cu nanoparticles on graphene.It is well known that graphene has an ultra-large specific surface area,ultra-high conductivity and light transmittance,which can provide a large number of active sites for photocatalytic reaction and effectively reduce the recombination rate of photogenerated electrons and holes.However,the current general methods for synthesizing graphene are limited by consumption of time and complicated multiple steps,making it impossible to mass produce high quality graphene.There is an urgent need for a simple,green and reliable method for the synthesis of graphene.Therefore,biomass,having an inexpensive,non-toxic and readily available property,has attracted more and more attention in the preparation of graphene.Finding effective biomass precursors is the key to synthetic graphene.Therefore,this paper synthesized Multi-layer graphene from Plumeria rubra,exploring the effect of the amount of potassium hydroxide and calcination temperature on the performance of graphene.The experimental results show that when the ratio of potassium hydroxide to precursor is 2:1 and the calcination temperature is 1000°C,the performance of the multi-layer graphene is the best.It has an ultra-high specific surface area(1581 m² g^-1)and a large pore volume(0.916 cm³ g^-1),a high degree of graphitization(I_D/I_G=0.77,I_2D/I_G=0.53)and a 5-layer microstructure.In this paper,a vacuum-blocked reaction system was used to synthesize copper nanoparticles by photoreduction under vacuum and loaded on the surface of the multi-layer graphene.Forming a composite catalyst?Cu/PGS?can effectively the oxidation of Cu nanoparticles.The effects of the addition amount of sacrificial agent?lactic acid?and the degree of graphitization of graphene on the photocatalytic activities for hydrogen evolution of Cu/PGS were investigated,and the cyclic stability of the composite was also tested.The experimental results show that the highest hydrogen production rate of Cu/PGS-2-1000reaches 4.87 mmol g^-1 h^-1,and has strong photocatalytic stability.Furthermore,we analyzed the effect of photoreduction on graphene through a series of tests.The results show that photogenerated electrons can reduce graphene,reducing the degree of defects and oxidation of graphene,and increasing the degree of graphitization of graphene.Finally,this paper also explores the mechanism of Cu/PGS photocatalytic hydrogen evolution,studies the process of photogenerated electrons and holes generation and separation,and explores the process of photogenerated electron reduction of graphene and H⁺.