Colloidal synthesis method such as oleylamine(OAm)-stabilized process is of great interest for obtaining uniform and highly dispersed platinum nanoparticle catalysts, yet the ligand may unavoidably inhibit their elect...Colloidal synthesis method such as oleylamine(OAm)-stabilized process is of great interest for obtaining uniform and highly dispersed platinum nanoparticle catalysts, yet the ligand may unavoidably inhibit their electro-catalytic performance. Thus, fully removing these ligands is critical to activate catalyst surface. Previous research of OAm removal process pointed that thermal annealing was the most effective way in comparison with other methods such as chemical washing, UV–Ozone irradiation and cyclic voltammetry sweeping, but generally resulting in undesired growth of platinum nanoparticle. Few studies concerning a more efficient ligand removal process have been published yet. In this work we proposed a platinum in-situ catalytic OAm combustion strategy to elucidate the removal mechanism of OAm ligands in thermal process and the key experimental parameters were also optimized. In addition, heat flow signal based on differential scanning calorimetry(DSC) measurement as a sensitive indicator, is suggested to reveal the ligand removal efficiency, which is much more reliable than the traditional spectroscopy.In comparison with commercial Pt/C sample, such a surface clean Pt/C electrocatalyst has shown an enhanced specific activity for oxygen reduction reaction. Our removal strategy and the evaluation method are highly instructive to efficient removal of different organic ligands.展开更多
The stability constants of some ternary mixed-ligand complexes, Pt(Phen)(CA)+, where Phen=1,10-phenanthroline and CA- =carboxylate, were determined by means of potentiometric pH titration in aqueous solutions(I=0.1 mo...The stability constants of some ternary mixed-ligand complexes, Pt(Phen)(CA)+, where Phen=1,10-phenanthroline and CA- =carboxylate, were determined by means of potentiometric pH titration in aqueous solutions(I=0.1 mol/L, KNO 3; 25 ℃), and the stability of them was compared with that of the corresponding binary complexes. It was revealed that the ternary complexes containing phenylalkane carboxylates ligands(PCA-) are much more stable than those formed with formate and acetate. The results indicate that there exist the intramolecular aromatic-ring interactions between the phenanthroline ring of Phen and the phenyl moiety of ligand PCA- in the ternary mixed-ligand Pt(Phen)(PCA)- complexes. The extent of the stacking interactions, which depends on the number of methylene groups between the phenyl moieties and the coordinated phenylalkane carboxylate groups, was calculated. The best-fitted stack was obtained for the complexes with 2-phenylacetate and 3-phenylpropionate as the ligands.展开更多
Six-nuclear complexes of Platinum(II) with cleavage of a cystamine dihydrochloride by β-mercaptoethylamine with composition [Pt<sub>6</sub>(H<sub>2</sub>NCH<sub>2</sub>CH<sub>...Six-nuclear complexes of Platinum(II) with cleavage of a cystamine dihydrochloride by β-mercaptoethylamine with composition [Pt<sub>6</sub>(H<sub>2</sub>NCH<sub>2</sub>CH<sub>2</sub>S)<sub>8</sub>]Cl<sub>4</sub>·5H<sub>2</sub>O had been syntesized for the first time. Structure of the complex had been installed together with IKS- and XRD analysis. It has been established that each atom of platinum is surrounded by two atoms of sulfur and nitrogen due to bidentate coordination of a ligand. Only two of the six platinum atoms are on the same plane;other four atoms are in the different crossing planes. Four platinum atoms form adurable metal chelate cycles, which collapse over temperature 260℃. The results of IR spectroscopy confirmed with the RS-analysis.展开更多
基金the financial support by DICP Grant no.ZZBS201705。
文摘Colloidal synthesis method such as oleylamine(OAm)-stabilized process is of great interest for obtaining uniform and highly dispersed platinum nanoparticle catalysts, yet the ligand may unavoidably inhibit their electro-catalytic performance. Thus, fully removing these ligands is critical to activate catalyst surface. Previous research of OAm removal process pointed that thermal annealing was the most effective way in comparison with other methods such as chemical washing, UV–Ozone irradiation and cyclic voltammetry sweeping, but generally resulting in undesired growth of platinum nanoparticle. Few studies concerning a more efficient ligand removal process have been published yet. In this work we proposed a platinum in-situ catalytic OAm combustion strategy to elucidate the removal mechanism of OAm ligands in thermal process and the key experimental parameters were also optimized. In addition, heat flow signal based on differential scanning calorimetry(DSC) measurement as a sensitive indicator, is suggested to reveal the ligand removal efficiency, which is much more reliable than the traditional spectroscopy.In comparison with commercial Pt/C sample, such a surface clean Pt/C electrocatalyst has shown an enhanced specific activity for oxygen reduction reaction. Our removal strategy and the evaluation method are highly instructive to efficient removal of different organic ligands.
基金Supported by the Foundation of Academ y L eader of Zhejiang Gongshang U niversity(No.19972 0 0 2 )
文摘The stability constants of some ternary mixed-ligand complexes, Pt(Phen)(CA)+, where Phen=1,10-phenanthroline and CA- =carboxylate, were determined by means of potentiometric pH titration in aqueous solutions(I=0.1 mol/L, KNO 3; 25 ℃), and the stability of them was compared with that of the corresponding binary complexes. It was revealed that the ternary complexes containing phenylalkane carboxylates ligands(PCA-) are much more stable than those formed with formate and acetate. The results indicate that there exist the intramolecular aromatic-ring interactions between the phenanthroline ring of Phen and the phenyl moiety of ligand PCA- in the ternary mixed-ligand Pt(Phen)(PCA)- complexes. The extent of the stacking interactions, which depends on the number of methylene groups between the phenyl moieties and the coordinated phenylalkane carboxylate groups, was calculated. The best-fitted stack was obtained for the complexes with 2-phenylacetate and 3-phenylpropionate as the ligands.
文摘Six-nuclear complexes of Platinum(II) with cleavage of a cystamine dihydrochloride by β-mercaptoethylamine with composition [Pt<sub>6</sub>(H<sub>2</sub>NCH<sub>2</sub>CH<sub>2</sub>S)<sub>8</sub>]Cl<sub>4</sub>·5H<sub>2</sub>O had been syntesized for the first time. Structure of the complex had been installed together with IKS- and XRD analysis. It has been established that each atom of platinum is surrounded by two atoms of sulfur and nitrogen due to bidentate coordination of a ligand. Only two of the six platinum atoms are on the same plane;other four atoms are in the different crossing planes. Four platinum atoms form adurable metal chelate cycles, which collapse over temperature 260℃. The results of IR spectroscopy confirmed with the RS-analysis.
基金supported by the National Natural Science Foundation of China(21073143)“Chunhui Project”from the Ministry of Education of China(Z2009-1-71002,Z2009-1-71006)+2 种基金Graduate Starting Seed Fund of Northwestern Polytechnical University(NPU),China(Z2015152)NPU Foundation for Graduate InnovationChina~~
