Preparation Of Phenanthroline Graphite-Like Alkyne And Elementary Molecular Palladium Catalysts And Study Of Electrocatalytic Carbon Dioxide Reduction Performance

In recent years,the rapid development of industry and human society has led to the excessive consumption of fossil fuels such as coal,oil and natural gas.In this context,CO₂ reduction is considered to be an effective way of carbon resource recycling and sustainable fuel production.The research core of CO₂ reduction is the development of efficient catalysts,which can be divided into homogeneous and heterogeneous catalysts.Homogeneous catalysts have homogeneous and isolated active sites and specific structures,but there are some problems such as insufficient stability,difficult purification of products and difficult recycling of catalysts.However,heterogeneous catalysts are relatively stable in structure,easy to recycle,but have complex and diverse structures and difficult to accurately synthesize.Therefore,it has always been a challenging problem in the field of CO₂ reduction to balance the advantages and disadvantages of homogeneous and heterogeneous catalysts and to develop catalytic materials with high activity,stability and clear structure.In this paper,the reaction precursor hexaalkyne benzene and3,8-dibromo-1,10-phenanthroline were conjugated by Sonogashira coupling reaction to successfully construct Phenanthroline graphite-like alkyne framework material,and the corresponding elementary small molecular ligand structure of Phenanthroline graphite-like framework material was synthesized.In addition,theπbond of C≡C in the structure of the N-doped graphite-like alkyne material has interaction with the d orbital of the metal atom,Therefore,both pyridine nitrogen and ortho-angle alkyne bond positions in the material can be used as metal monatomic anchoring sites.By using the wet chemical method,the Pd metal was directly introduced into the Phenanthroline graphite-like alkyne framework material/elementary small molecular ligand structure through the anchoring of metal by the included angle alkyne bond and the nitrogen-containing ligand.Finally,Phenanthroline graphite-like alkyne CNTs-p GDY-Pd_x catalyst materials with different palladium loads and two different palladium molecular catalyst materials were obtainedThe results showed that Phenanthroline graphite-like alkyne CNTs-p GDY-Pd_xcatalyst material and two kinds of palladium molecular catalyst materials could be used for electrocatalytic synthesis of syngas from CO₂RR.When the palladium loading capacity was 1.78wt%,CNTs-p GDY-Pd₃ catalyst could be used in the potential range of-0.8 V to-1.2 V vs.RHE.The syngas CO/H₂ is stable at 1～1.5.For the two kinds of palladium molecular catalysts,the syngas CO/H₂ of PHEN-Pd₂catalyst sample is about 2 in the potential range of-0.8 V to-1.0 V vs.RHE,while the syngas CO/H₂ of PHEN-Pd₃ catalyst sample is about 0.5 in the potential range of-0.8 V to-1.1 V vs.RHE.The ratio of syngas meets the industrial Fischer-Tropsch synthesis.This work provides a new idea for the development of novel and low-cost heterogeneous catalysts,and reveals the possibility of application of N-doped graphite-like alkyne base materials and their corresponding small molecule ligands in electrocatalytic CO₂RR synthesis gas field.