| Nano-materials are extremely important catalytic materials,because of their unique size effect,crystal surface effect and synergistic effect,are widely used in industrial production,including hydrogenation industry,fuel cell,gas sensing and electrochemical sensing equipment.The catalytic activity and stability of nano-particle catalysts depend largely on the size and morphology of particles,and the nanometer materials with uniform appearance,small size and homogeneous dispersion have attracted wide attention because of their excellent catalytic properties.In this paper,carbon supported ultrafine dispersed transition metal catalysts are prepared by means of organic complexes.Organic complexes are the organic compounds containing coordination units,because of their flexible chemical structure,with a variety of coordination,with transition metal or rare-earth metal forming metal complexes,can effectively regulate the metal center of the electronic structure,thus affecting its catalytic performance.In this paper,different organic ligands are selected to control the growth rate of metal nanoparticles by regulating the oxidation reduction electrode potential of metal ions.The space limiting effect of ligand was used to inhibit the growth of metal nanoparticles.Through the interaction between the organic ligands and the metal nanoparticles,the electronic structure of the metal active center is regulated.In this way,high performance carbon supported transition metal catalyst is prepared.the main contents are as follows:1,In this manuscript,we presented a one-step reduction approach to the synthesis of highly dispersed and ultrafine phosphonate functionalized Pd nanoparticles supported by carbon(Pd/C)by using XC-72 as the catalyst support,ethylenediamine tetramethylene phosphonic acid(EDTMPA)as both coordination agent and stabilizer,palladium chloride(PdCl2)as the precursor and sodium borohydride(NaBH4)as the reducing agent,respectively.Transmission electron microscopy(TEM),X-ray diffraction(XRD)results indicated that the average particle size and the dispersion degree in the Pd/C catalysts are 2.7 nm and 37.1%,much higher than that of the commercial catalysts.The activation energy of catalytic hydrogenation for rhodamine(RhB)and p-nitrophenol(4-NP)for the obtained catalyst are calculated to be 27.1 and 16.9 kJ·mol-1,respectively,obviously lower than that in the commercial Pd/C catalyst(57.2 and 55.7 kJ·mol-1).2.Using inert salt NaCl as a hard template and stabilizer,Platinum Nitrate(Pt(NO3)2)and Nickel nitrate(Ni(NO3)2)as metal source,glucose(C6Hi2O6)as carbon source,through grinding-dissolving-crystallization process,and combine by one-step high temperature approach,a carbon nanosheet(PtNi@GCNS)with PtNi intermetallic compound nanoparticles were synthesized.Because of its unique two-dimensional porous structure and good synergistic effect between the embedded ultrafine PtNi intermetallic compounds,it has good catalytic activity on the hydrogenation reduction of P-nitrophenol(4-NP)(k = 0.276 min-1),and can convert 4-NP to 4-AP completely within 10 minutes.It also shows good cyclic stability.3.The tetra-substituted phenylamine phthalocyanine palladium(PdPc)is used as a metal precursor,and graphene oxide(GO)is used as a carrier.PdPc and GO can be combined by π-π conjugate to synthesize PdPc/GO complex.A Pd monoatomic catalyst supported on the surface of reduced graphene oxide was prepared by reducing Pd(II)at low temperature in an atmosphere of argon and hydrogen with PdPc/GO.The catalyst has excellent catalytic performance for the hydrogenation reaction of rhodamine B(k=0.083 min-1).4.The SiO2@GO nanometer microspheres were synthesized by the method of laminated self-assembly assisted with the template of SiO2.Then,by the strong π-πinteraction between GO and FePc,the FePc is loaded on the surface of the SiO2@GO nanometer microsphere to obtain the SiO2@GO/FePc complex.The SiO2@GO/FePc complex was pyrolysis at high temperature under the nitrogen atmosphere,and the SiO2@GO nanometer microspheres(SiO2@GO/Fe-N-C)with single atom iron on the surface were obtained.Finally,the Fe single atom catalyst with three-dimensional hollow nanosphere structure was obtained by removing the SiO2 template with NaOH solution.Because of its unique three-dimensional structure,a single atom of Fe disperses on the 3D GO surface,exposing all the metal activity centers to the surface and fully contacting the electrolyte to make it perform excellent catalytic performance against ORR.Compared with commercial Pt/C catalysts,The half-wave potential of the 3D RGO/Fe-N-C in the KOH solution to the oxygen reduction reaction(ORR)was 0.85 V,which was positive shift 20 mV than Pt/C,showing superior electrocatalytic activity.Moreover,3D RGO/Fe-N-C showed better anti-methanol and toxicity resistance(SOx,NOx)in the oxygen reduction reaction(ORR). |
