Synthesis Of Bimetallic Pt₃Co Alloy Nanocrystals For Heterogeneous Hydrogenation Of CO₂ To Methanol

CO₂ "greenhouse gas" poses genuine concerns and threats in the shape of ecological climate changes and global warming as a result of extensive combustion of fossil fuels.The environmental problems related to CO₂ emissions are significantly serious and therefore,people and governments are paying due attention to the efficient utilization of CO₂.Methanol is consequently good choice of liquid fuel with a relatively high energy density,because methanol can be produced by heterogeneous hydrogenation of CO₂.The utilization of methanol is highly preferred as an alternative to hydrogen due to its ability of storing and its simplicity in transporting,handling and storing of energy.（1）The first chapter highlights the major motivation to investigate the issue in detail.The rationale behind efficient use of CO₂ for synthesis of methanol has numerous superiorities because it is the exploitation of renewable fuel sources,avoidance of expensive CO₂ sequestration strategies,and reprocessing of CO₂ into precious liquid fuels and chemicals by alleviating the greenhouse effect.CO₂ molecule is thermodynamically very stable and heterogeneous catalytic activation of CO₂ plays a fundamental function in chemical conversion of CO₂ into efficient liquid chemicals.Moreover,it is helpful in fuels which require high energy demands and need to utilize high quality heterogeneous catalysts,proficient in motivating its selective transformation into targeted liquid fuels and chemicals.CO₂ is an attractive C1 building block that is most abundant raw substance in the environment,safe and renewable.Typically,an important strategy for utilization of CO₂ is heterogeneous hydrogenation of CO₂ for synthesizing valuable industrial chemicals including methanol,methane,formic acid,etc.which is one of the most economical way for storing energy.Conversion of CO₂ into useful chemicals and fuels helps not only minimize CO₂ concentrations,recycling of carbon resources,but also serves as an alternative economical feedstock for future petrochemical engineering and chemical industry.（2）The second chapter is devoted to the explanation of the innovative synthetic strategies that are employed for bimetallic nanocrystals,and which are considered novel synthetic methods in the world of material chemistry to adjust and engineer the material performance.In the second part,advanced analytical characterization techniques for bimetallic nanocrystals have been discussed in detail and have identified their obvious structure-property relationship.The author briefly illustrated absolute experimental and computational models attractive to explain actual reaction mechanisms of CO₂ hydrogenation to methanol for the designing of active and selective heterogeneous catalysts.（3）The third chapter discusses the synthesis of Pt₃Co nanocrystals with superior catalytic activity towards CO₂ hydrogenation to methanol.During the activation of CO₂,the electron transfer to CO₂ is a vital step.In order to boost up the heterogeneous catalytic activity,it is of paramount importance to engineer and design the electronic properties of heterogeneous catalysts for CO₂ hydrogenation.Pt nanocubes,Pt₃Co nanocubes,Pt₃Co octapods and Pt octapods,were investigated,where Pt₃Co octapods attained the most excellent catalytic activity.The existence of charge transfer between Pt and Co and multiple sharp tips both facilitate the accumulation of negative charges in the vertices of Pt₃Co octapods on the Pt atoms.Furthermore,diffuse reflectance infrared fourier transform spectroscopy proved that the high negative charge density in the vertices of the Pt₃Co octapods at the Pt atoms contributed for the activation of CO₂ and accordingly improved the catalytic activity.