Bimetallic Pt-based catalysts have been extensively investigated to enhance the performance of direct methanol fuel cells(DMFCs) because CO, a by-product, reduces the activity of the pure Pt catalysts. Herein, we synt...Bimetallic Pt-based catalysts have been extensively investigated to enhance the performance of direct methanol fuel cells(DMFCs) because CO, a by-product, reduces the activity of the pure Pt catalysts. Herein, we synthesized Pt-Pb hexagonal nanoplates as a model catalyst for the methanol oxidation reaction(MOR) and further controlled the Pt and Pb distributions on the surface of the nanoplates through acetic acid(HAc) treatment. As a result, we obtained Pt-Pb nanoplates and HAc-treated Pt-Pb nanoplates with homogeneous and heterogeneous distributions of the Pt-Pb alloy surfaces, respectively. We showed that the MOR activity and stability of the Pt-Pb nanoplates improved compared to those of the HAc-treated Pt-Pb nanoplates, mainly due to the enhanced CO tolerance and the modified electronic structure of Pt under the influence of the oxophilic Pb.展开更多
Based on the analysis of tin penetration mechanism in the float glass process, the oxidation model of stannous ion is constructed considering the oxygen activity and the redox reaction in the glass surface layer. The ...Based on the analysis of tin penetration mechanism in the float glass process, the oxidation model of stannous ion is constructed considering the oxygen activity and the redox reaction in the glass surface layer. The calculation of stannous ion's oxidation rate makes it possible to predict both stannous and stannic ion's concentrations independently. And it is also the necessary precondition for the numerical verification of tin penetration mechanism. Coupled diffusion simulation method is established to simulate the penetration process of both stannous and stannic ions simultaneously. The result shows that when the green glass is formed in the reducing atmosphere in tin bath, the stannic ion is accumulated at the position where oxygen activity changes sharply. Satellite peak (internal local concentration maximum) occurs in the tin concentration profile of green glass, which is quite different from that in low iron glass. Compared with gradually cooling temperature regulation, the tin penetrated shifts to greater depth and the depth and magnitude of the satellite peak also increase when reheating temperature regulation is applied. In order to reduce the amount of penetrated tin, the residual time in the high temperature region should be shortened.展开更多
文摘Bimetallic Pt-based catalysts have been extensively investigated to enhance the performance of direct methanol fuel cells(DMFCs) because CO, a by-product, reduces the activity of the pure Pt catalysts. Herein, we synthesized Pt-Pb hexagonal nanoplates as a model catalyst for the methanol oxidation reaction(MOR) and further controlled the Pt and Pb distributions on the surface of the nanoplates through acetic acid(HAc) treatment. As a result, we obtained Pt-Pb nanoplates and HAc-treated Pt-Pb nanoplates with homogeneous and heterogeneous distributions of the Pt-Pb alloy surfaces, respectively. We showed that the MOR activity and stability of the Pt-Pb nanoplates improved compared to those of the HAc-treated Pt-Pb nanoplates, mainly due to the enhanced CO tolerance and the modified electronic structure of Pt under the influence of the oxophilic Pb.
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2007CB206901)the Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (Grant No. 2006BAF02A27)
文摘Based on the analysis of tin penetration mechanism in the float glass process, the oxidation model of stannous ion is constructed considering the oxygen activity and the redox reaction in the glass surface layer. The calculation of stannous ion's oxidation rate makes it possible to predict both stannous and stannic ion's concentrations independently. And it is also the necessary precondition for the numerical verification of tin penetration mechanism. Coupled diffusion simulation method is established to simulate the penetration process of both stannous and stannic ions simultaneously. The result shows that when the green glass is formed in the reducing atmosphere in tin bath, the stannic ion is accumulated at the position where oxygen activity changes sharply. Satellite peak (internal local concentration maximum) occurs in the tin concentration profile of green glass, which is quite different from that in low iron glass. Compared with gradually cooling temperature regulation, the tin penetrated shifts to greater depth and the depth and magnitude of the satellite peak also increase when reheating temperature regulation is applied. In order to reduce the amount of penetrated tin, the residual time in the high temperature region should be shortened.
