通过两步还原法制备了Pd/Ni双金属催化剂.由于金属Pd原子在先行还原的Ni纳米粒子表面的外延生长以及其在Ni表面及Pd表面生长表现出的吉布斯自由能差异,最终导致了异结构Pd/Ni纳米粒子的形成.高分辨电子透射显微镜结果证实了异结构的存在,然而X射线衍射测量表明Pd/Ni纳米粒子具有类似于Pd的面心立方结构.制备的Pd/Ni纳米粒子与同等条件下合成的Pd纳米粒子相比对甲酸氧化呈现了更高的电催化活性,而且电催化稳定性也要明显优于纯Pd纳米粒子,证明Pd/Ni双金属催化剂是可选的直接甲酸燃料电池阳极催化剂.双金属催化剂对甲酸氧化电催化活性和稳定性增强可能是Ni原子的修饰改变了Pd粒子表面配位不饱和原子的电子结构所致.
任明军
,
邹亮亮
,
陈举
,
袁婷
,
黄庆红
,
张海峰
,
杨辉
,
封松林
. Pd/Ni异结构纳米催化剂的制备及其对甲酸氧化的电催化[J]. 电化学, 2012
, 18(6)
: 515
-520
.
DOI: 10.61558/2993-074X.2620
A Pd/Ni bimetallic nanostructured electrocatalyst was fabricated via a two-step reduction route. Owing to an epitaxial growth of Pd atoms on the surface of Ni nanoparticles, heterostructured Pd/Ni nanocomposites were formed and verified by high resolution transmission electron microscopy combined with energy-dispersion X-ray spectroscopy. X-ray diffraction confirmed that the as-prepared Pd/Ni nanocomposites possessed a single face-centered-cubic (fcc) Pd structure, probably due to a weaker diffraction intensity of metallic Ni and/or overlapping by that of Pd. The intrinsic catalytic activity on the Pd/Ni is higher than that on the Pd. Moreover, the durability of formic acid oxidation on the Pd/Ni was much enhanced over the Pd nanoparticles. The change in electronic structure of the surface coordination unsaturated Pd atoms and the possible dissolution of Ni species from the Pd/Ni heterostructure may account for such an improved durability for formic acid oxidation.
[1] Wang J Y, Zhang H X, Jiang K, et al. From HCOOH to CO at Pd electrodes: A surface-enhanced infrared spectroscopy study[J]. Journal of the American Chemical Society, 2011, 133(38): 14876-14879.
[2] Zhang H X, Wang S H, Jiang K, et al. In situ spectroscopic investigation of CO accumulation and poisoning on Pd black surfaces in concentrated HCOOH[J]. Journal of Power Sources, 2012, 199(1): 165-169.
[3] Yu X W, Pickup P G. Mechanistic study of the deactivation of carbon supported Pd during formic acid oxidation[J]. Electrochmistry Communications, 2009, 11(10): 2012-2014.
[4] Ren M J, Kang Y Y, He W, et al. Origin of performance degradation of palladium-based direct formic acid fuel cells[J]. Applied Catalysis B: Environmental, 2011, 104(1/2): 49-53.
[5] Wang X M, Xia Y Y. Electrocatalytic performance of PdCo-C catalyst for formic acid oxidation[J]. Electrochemistry Communications, 2008, 10(10): 1644-1646.
[6] Hann J L, Stafford K M, Morgan R D, et al. Performance of the direct formic acid fuel cell with electrochemically modified palladium-antimony anode catalyst[J]. Electrochimica Acta, 2010, 55(7): 2477-2481.
[7] Hammer B, N?rskov J K. Theoretical surface science and catalysis-calculations and concepts[J]. Advances in Catalysis, 2000, 45: 71-129.
[8] Ruban A, Hammer B, Stoltze P, et al. Surface electronic structure and reactivity of transition and noble metals[J]. Journal of Molecular Catalysis A: Chemical, 1997, 115(3): 421-429.
[9] Bligaard T, N?rskov J K. Ligand effects in heterogeneous catalysis and electrochemistry[J]. Electrochimica Acta, 2007, 52(18): 5512-5516.
[10] Strasser P, Koh S, Anniyev T, et al. Lattice-strain control of the activity in dealloyed core-shell fuel cell catalysts[J]. Nature Chemistry, 2010, 2(6): 454-460.
[11] Wang D S, Li Y D. Bimetallic nanocrystals: Liquid-phase synthesis and catalytic applications[J] Advanced Materials, 2011, 23(9): 1044-1060.
[12] Zhang S, Shao Y Y, Yin G P, et al. Electrostatic self-assembly of a Pt-around-Au nanocomposite with high activity towards formic acid oxidation[J]. Angewandte Chemie International Edition, 2010, 49(12): 2211-2214.
[13] Li R S, Wei Z, Huang T, et al. Ultrasonic-assisted synthesis of Pd-nialloycatalysts supported on multi-walled carbon nanotubes for formic acid electrooxidation[J]. Electrochimica Acta, 2011, 56(19): 6860-6865.
[14] Kibler L A, El-Aziz A M, Hoyer R, et al. Tuning reaction rates by lateral strain in a palladium monolayer[J]. Angewandte Chemie International Edition, 2005, 44(14): 2080-2084.
[15] Oezaslan M, Heggen M, Strasser P. Size-dependent morphology of dealloyed bimetallic catalysts: Linking the nano to the macro scal[J]. Journal of the American Chemical Society, 2012, 134(1): 514-524.