不同方法制备Pt/C催化剂对燃料电池催化活性的影响

分别采用高压有机溶剂法和回流法不同的制备方法,制备了含铂20%(w)的催化剂Pt/C-HP(高压有机溶剂法)和Pt/C-Reflux(回流法)。实验发现:对于甲醇的阳极氧化过程,高压有机溶胶法制得的催化剂活性较高,催化剂Pt/C-HP甲醇氧化峰电流密度是Pt/C-Reflux的1.5倍,且远远高于商业催化剂JM3000含铂20%(w)Pt/C催化剂,催化剂Pt/C-Reflux甲醇氧化峰电流密度与商业催化剂JM3000催化剂相当。采用X射线衍射(XRD)、透射电镜(TEM)、循环伏安法(CV)等方法对催化剂进行表征的结果表明:高压有机溶胶法制得的催化剂分散性比回流法制得的催化剂好,使得前者催化剂的电化学活性比表面积得到了显著的提高。     

A high dispersed Pt0.35Pd0.35Co0.30/C as superior catalyst for methanol and formic acid electro-oxidation

Pt：Pd：Co ternary alloy nanoparticles were synthesized by sodium borohydride reduction under nitrogen, and were supported on carbon black as catalysts for methanol and formic acid electro-oxidation. Compared with Pt0.65C00.35/C, Pt/C, Pd0.65C00.35/C, and Pd/C catalyst, Pt0.35Pd0.35Co0.30/C exhibited relatively high durability and strong poisoning resistance, and the Pt-mass activity was 3.6 times higher than that of Pt/C in methanol oxidation reaction. Meanwhile, the Pt0.35Pd0.35Co0.30/C exhibited excellent activity with higher current density and higher CO tolerance than that of Pt0.6sCo0.35/C, Pt/C, Pd0.65C00.35/ C, and Pd/C in formic acid electro-oxidation.     

Concave Pt-Cu-Fe ternary nanocubes:One-pot synthesis and their electrocatalytic activity of methanol and formic acid oxidation

Concave nanostructures may be developed to improve the specific mass activity of a catalyst for formic acid and methanol electro-oxidation. In this work, we report the elctrocatalytic oxidation of methanol and formic acid in acid medium over concave Pt-Cu-Fe ternary nanocubes (NCs), obtained by the galvanic exchange of Pt and Fe on Cu NCs. The concave Pt-Cu-Fe NCs exhibited improved electrooxidation performance contrasted to Pt-Cu NCs and purchased commercial Pt/C as demonstrated by their improved durability, lower onset potential, and more preferable anti-poisoning properties. These properties are believed to originate from the tailored concave structure of the catalyst and possible synergetic effects among the components of the Pt-Cu-Fe NCs.     

Salt effect on molecular orientation at air/liquid methanol interface

The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy(SFG-VS). We clarified that the average tilting angle of the methyl group to be u = 308 58 at the air/pure methanol surface assuming a d-function orientational distribution. Upon the addition of 3 mol/L Na I, the methyl group tilts further away from the surface normal with a new u = 418 38. This orientational change does not explain the enhancement of the SFG-VS intensities when adding Na I, implying the number density of the methanol molecules with a net polar ordering in the surface region also changed with the Na I concentrations. These spectroscopic findings shed new light on the salt effects on the surfaces structures of the polar organic solutions. It was also shown that the accurate determination of the bulk refractive indices and Raman depolarization ratios for different salt concentrations is crucial to quantitatively interpret the SFG-VS data.     

New measurements and analysis of the far-infrared spectrum of CH2DOH in the lowest torsional vibrational state (e0)

In this work the far infrared (FIR) absorption spectrum has been measured for the asymmetrically mono deuterated Methanol (CH₂DOH) species in the wavenumber range of 15–1200 cm⁻¹ better accuracy and signal/noise ratio than known before. Assignments have been made for b-type transitions in the lowest lying torsional vibrational state trans-(e₀) for a wide range of rotational angular momentum. The assignments have been rigorously confirmed by the residual loop defect methods. The ^rR–branch wavenumbers are analyzed by the usual state dependent expansion parameters and the Q-Branch origins. These origins have been used to calculate the torsional and torsional-rotation interaction contributions. These findings are in good agreement with predicted from the Hamiltonian model described in recent publications. A large number of assignments have also been made in the millimeter wave spectrum recorded earlier and thereby evaluated the asymmetry splitting parameters for 4 different axial rotational angular momentum quantum numbers. The analysis and interpretation of the spectra are reported. New assignments for about 260 transitions are included the text and a catalog of about 1500 transitions belonging to the e₀ species is prepared (Appendix 1) and is made available through the open server in “Research Gate” and will be freely available to others.     

Solid deformation induced by the adsorption of methane and methanol under sub- and supercritical conditions

Carbonaceous materials with some degree of flexibility in their physical structure can expand or contract under the influence of the forces exerted by adsorbed molecules. To gain insight into how adsorption of non-polar and polar fluids could deform a carbon solid, we present GCMC simulations of sub- and supercritical adsorption of methane and methanol in slit-shaped pores whose walls are made of graphene layers. Our extensive simulation study shows that there is a strong correlation between solvation pressure and solid deformation, and that the expansion or contraction of the pore strongly depends on adsorbate loading, temperature and pore size.     

“三明治式”多层Au/Pt复合薄膜的制备及其对甲醇的电氧化

采用界面组装、欠电位沉积和氧化还原置换反应组合方法制备了单层Pt/Au复合薄膜, 并且不需要任何有机偶联剂; 组装单层Pt/Au复合薄膜为三类多层Pt/Au复合薄膜: (Pt/Au)_n、Pt_m/Au和(Pt₃/Au)_k (n、m和k分别为Pt/Au、Pt和Pt₃/Au的层数). 采用电子显微镜研究了Au纳米粒子单层膜和Pt/Au复合多层膜的形貌. 对于所有的多层膜电极而言, 其电化学活性面积随着层数的增加而增加. 通过研究甲醇在每一类Pt/Au复合薄膜上的氧化电流密度, 考察了其对甲醇的电催化和抗毒化性能. 对于同一类复合薄膜而言, 甲醇分别在(Pt/Au)₃、Pt₃/Au和(Pt₃/Au)₂电极上均具有最大的氧化电流密度, 且优于本体Pt电极. 在这三种电极中, (Pt/Au)₃电极无论从电流密度上还是从抗毒化能力上讲, 其性能是最好的, 而且其抗毒化能力也优于商业Pt/C催化剂. 这种良好的催化性能源于Au和Pt之间最大化的协同效应, 这取决于Pt和Au原子比率以及Pt纳米层和Au纳米层之间的排布方式.