Preparation And Electrocatalytic Properties Of Carbon-based Material Catalysts

With the advantages of high sensitivity,simple equipment,easy operation,safety,and environmental protection,electrocatalysis can be widely used to solve problems such as environmental pollution,energy crisis,and the greenhouse effect.Carbon-based materials are widely used in the field of electrocatalysis due to their low price,environmental friendliness,high electrical conductivity,stability,large specific surface area,diverse pore structure,rich functional groups,recyclability,and good plasticity.Therefore,the development of inexpensive,readily available,highly active,and stable carbon-based electrocatalysts can play an important role in the widespread development and application of electrocatalytic technology.In this thesis,a series of carbon-based electrocatalysts based on carbon materials were prepared by non-metallic heteroatom doping,noble metal loading,and transition metal loading,and applied to the electrocatalytic reactions of p-nitrophenol reduction,hydrogen precipitation,and carbon dioxide reduction,respectively.The conformational relationships between the physical and chemical properties of the catalysts and their electrocatalytic activities were also investigated.The main elements are as follows.（1）N-doped carbon dry gels were synthesized by in situ condensation pyrolysis of formaldehyde and dicyandiamide as C and N sources,and then N,P or N,S co-doped carbon dry gels were prepared by introducing P from diammonium hydrogen phosphate or S atoms from thiourea into the carbon skeleton using vapor deposition and were used for the electrocatalytic reduction of p-nitrophenol.The N,P co-doped carbon dry gels（P-NDCX-1.0）with 9.09 g,2.0 g,and 1.0 g of C,N,and P precursors,respectively,showed the best activity and good stability for the reduction reaction,with a reduction peak potential of-0.569 V.After100 CV cycles,the reduction peak potential was only shifted to the negative potential by 14m V.After 100 CV cycles,the reduction peak potential was only shifted to the negative potential by 14 m V.（2）Pt-Ni alloy nanoparticle carbon dry gels with low Pt loading（0.78 wt.%）were prepared for electrocatalytic decomposition of hydrohydrogen evolution reaction（HER）by reflow loading and high-temperature hydrogen reduction using N-doped carbon dry gels as carriers.Electrochemical tests revealed that the Pt Ni₉/NDCX catalyst,obtained at a Pt/Ni mass ratio of 1/9,exhibited the best HER reaction activity:an overpotential of 40 m V at a current density of 10 m A/cm²,which was only 10 m V different from the commercial 20 wt.%Pt/C（30m V）under the same conditions,and a Tafel slope of 20.5 m V·dec^-1,which is lower than the commercial 20 wt.%Pt/C(23.1 m V·dec^-1);and the overpotential of Pt Ni₉/NDCX was only shifted by 3 m V after 10 h of continuous chrono-potentiation（CP,10 m A/cm²）.Ni nanoparticles were successfully synthesized and loaded onto NDCX carriers.The introduction of Ni nanoparticles was able to improve the dispersion of Pt nanoparticles,inhibit agglomeration at high temperatures and produce Pt-Ni synergy.（3）Cu/RGCN-7.5（carbon nitride exfoliation for 7.5 h）,an electrocatalyst loaded with Cu nanoparticles,was prepared for the CO₂ electrochemical reduction reaction（CO₂ER）by ultrasonic loading using carbon aerogel（RGCN）of graphene oxide（GO）and carbon nitride（g-C₃N₄）as carriers.The presence of carbon nitride enlarges the spacing of the graphene lamellae,providing a more specific surface area for the loading of Cu nanoparticles;sonication loading can control the particle size of Cu nanoparticles to below 5 nm.Electrochemical tests revealed that the products were CO,CH₄,C₂H₄ and C₂H₆,and the Cu/RGCN-7.5 catalyst had the highest Faraday efficiency for CO when the overpotential was-0.8V,reaching 12%,which was better than the graphene-loaded Cu nanoparticle catalyst（Cu/RG,4%）,and the graphene carrier（RG,2.5%）;Cu/RGCN-7.5 also had the highest C_dl（8.70μF/cm²）,which was 15.3 and3.72 times higher than RG（0.57μF/cm²）and Cu/RG（2.34μF/cm²）,respectively.