Controllable Synthesis Of Platinum Cobalt Bimetallic Nanomaterials With Enhanced Catalytic Properties

As we all know,the growing challenge of environmental pollution and energy shortage has always been one of the most urgent problems for the sustainable development of human beings.In recent years,the emergence of fuel cells and hydrogen energy provides a new idea.Platinum(Pt)catalyst is the most efficient single metal catalyst in many important applications.However,the commercialization of the Pt catalyst is seriously hindered,owing to the high price,low reserves and easy deactivation caused by the adsorbed poisonous CO-like intermediates.Therefore,to construct novel nanocatalysts with reduced usage of Pt and enhanced catalytic capability,Pt-based catalysts are prepared by introducing of transition non-precious metal(M = Co),and regulating morphology and structure based on the three-dimensional dendritic characters,hence increasing the active area and improving the catalytic activity.Specifically,we mainly used a simple one-pot solvothermal method,by utilizing cetyltrimethylammonium chloride(CTAC)as regulatory molecules and different reducing agents(glucose,L-glutamic acid,citric acid)to prepare the dendritic structure of PtCo nanoparticles.The structure of PtCo nanoparticles were mainly characterized by a series of characterization technologies(transmission electron microscopy(TElM),high-angle annular dark-field scanning-transmission electron microscopy-energy dispersive spectroscopy(HAADF-STEM-EDS),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS)et.al),whose formation mechanisms of the PtCo nanoparticles were also explored.The results showed that the prepared materials exhibited better catalytic performance compared with commercial Pt black and/or Pt/C catalysts,owing to the unique denderitic structure and the synergistic effect between Pt and Co.The specific contents are as follows:(1)Facile solvothermal synthesis of Pt76Co24 nanomyriapods for efficient electrocatalysisHerein,a one-pot solvothermal method was developed for constructing Pt76Co24 nanomyriapods(NMs)with abundant active sites and Pt-rich surfaces,where L-glutamic acid and CTAC were used as the green reductant and structure director,respectively.The architectures had larger electrochemically active surface area(ECSA)of 24.49 m2g-1 than Pt49Co51 nanoparticles(NPs,15.17 m2 g-1),Pt80Co20 NPs(16.71 m2 g-1)and commercial Pt black(20.35 m2 g-1),and exhibited superior catalytic performances for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER).The mass activity of Pt76Co24 NMs(105.26 mA mg-1pt)for ORR was double higher than Pt black(47.35 mA mg-1Pt).And the Pt76Co24 NMs catalyst exhibited better durable ability in acid media relative to Pt black and/or Pt/C.This work would have practical applications in catalysis,energy storage and conversion.(2)Facile solvothermal synthesis of Pt4Co multi-dendrites for efficient electrocatalysisIn this research,hierarchical Pt4Co multi-dendrites(MDs)with abundant active sites were synthesized by a one-pot solvothermal co-reduction approach,where CTAC,citric acid and oleylamine served as the structure-director,eco-friendly reducing agent and co-reductant,respectively.The architectures were mainly characterized by a series of characterization technologies,showing the enlarged ECSA of 28.27 m2 g-1,much enhanced mass activity and specific activity for ORR(279.14 mA mg-1Pt and 0.89 mA cm-2)and glycerol oxidation reaction(1422.56 mA mg-1pt,4.58 mA cm-2)comparable with commercial Pt black,along with the superior durability.These results demonstrate the potential applications of the synthesized Pt4Co MDs catalyst in energy storage and transformation.(3)Facile solvothermal synthesis of monodisperse Pt2.6Co1 nanoflowers for efficient electrocatalysisHerein,uniform Pt2.6Co1 nanoflowers(NFs)were synthesized in oleylamine by a one-pot solvothermal method,using CTAC and glucose as the capping agent and green reducing agent.The samples were mainly characterized by TEM,HAADF-STEM,XRD and XPS.The architectures had larger ECSA of 23.84 m2 g-1pt than Pti.2Co1 nanocrystals(NCs,14.96 m2 g-1Pt),Pt3.7Co1 NCs(16.96 m2 g-1pt)and Pt black(20.35 m2 g-1pt).And the as-obtained Pt2.6Co1 catalyst displayed superior catalytic performance and better durability for HER as compared to Pti.2Co1 NCs,Pt3.7Co1 NCs,commercial Pt/C and Pt black catalysts in acid and alkaline media.Meanwhile,ORR electrocatalytic performance of Pt2.6Co1 NFs in acid media is better than that in alkaline media.It indicates the great potential applications of the as-prepared catalyst in fuel cells.