Continuous mesoporous pd films by electrochemical deposition in nonionic micellar solution
Author(s)
Date
2017Source Title
Chemistry of Materials
Print ISSN
0897-4756
Publisher
American Chemical Society
Volume
29
Issue
15
Pages
6405 - 6413
Language
English
Type
ArticleItem Usage Stats
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Abstract
Mesoporous metals that combine catalytic activity and high surface area can provide more opportunities for electrochemical applications. Various synthetic methods, including hard and soft templating, have been developed to prepare mesoporous/nanoporous metals. Micelle assembly, typically involved in soft-templates, is flexible and convenient for such purposes. It is, however, difficult to control, and the ordering is significantly destroyed during the metal deposition process, which is detrimental when it comes to designing precisely mesostructured materials. In the present work, mesoporous Pd films were uniformly electrodeposited using a nonionic surfactant, triblock copolymer poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide), as a pore-directing agent. The interaction between micelles and metal precursors greatly influences the metal growth and determines the final structure. The water-coordinated species interact with the ethylene oxide moiety of the micelles to effectively drive the Pd(II) species toward the working electrode surface. From small-angle neutron scattering data, it is found that spherical P123 micelles, with an average diameter of ∼14 nm, are formed in the electrolyte, and the addition of Pd ions does not significantly modify their structure, which is the essence of the micelle assembly approach. The uniformly sized mesopores are formed over the entire mesoporous Pd film and have an average pore diameter of 10.9 nm. Cross-sectional observation of the film also shows mesopores spanning continuously from the bottom to the top of the film. The crystallinity, crystal phase, and electronic coordination state of the Pd film are also confirmed. Through this study, it is found that the optimized surfactant concentration and applied deposition potential are the key factors to govern the formation of homogeneous and well-distributed pores over the entire film. Interestingly, the as-prepared mesoporous Pd films exhibit superior electrocatalytic activity toward the ethanol oxidation reaction by fully utilizing the accessible active surface area. Our approach combines electrochemistry with colloidal and coordination chemistry and is widely applicable to other promising metals and alloy electrocatalysts.
Keywords
Catalyst activityCoordination reactions
Deposition
Digital storage
Electrocatalysts
Electrochemistry
Electrodeposition
Electrodes
Electrolytes
Ethylene
Mesoporous materials
Metals
Micelles
Neutron scattering
Nonionic surfactants
Oxide films
Palladium compounds
Polyethylene oxides
Reduction
Surface active agents
Synthetic metals
Co-ordination chemistries
Cross-sectional observations
Electrocatalytic activity
Electrochemical applications
Electrochemical deposition
Ethanol oxidation reaction
Mesostructured materials
Surfactant concentrations
Palladium