Polymer sphere lithography for solid oxide fuel cells: a route to functional, well-defined electrode structures

Abstract

As a first step towards mechanistic studies of fuel cell electrodes with both well-defined and functionally representative structural features, two-dimensional anti-dot metal films with tunable features are prepared. The fabrication employs a facile, sacrificial templating method, known as polymer sphere lithography, and the resulting metal films are fully connected, yet fully porous. Using initial bead sizes in the range of 500 nm to 3.2 mm and oxygen plasma etching to remove from ¼ to 3 ⁄4 of the original bead diameter, computed triple phase boundary densities in the porous films of 2,000 to 43,500 cm cm À2 are achieved. Image analysis shows the computed (theoretical) and experimental structural features to be in good agreement, demonstrating sufficient perfection in the films for electrochemical studies. Furthermore, thermal stability under hydrogen of thermally evaporated Ni films is excellent, with negligible change in triple phase boundary length as required for quantitative electrochemical measurements. Ultimately, these two-dimensional metallic networks may also serve as the platform for future fabrication of three-dimensional electrodes with truly optimized structural features.

Novel Microstructural Strategies To Enhance the Electrochemical Performance of La0.8Sr0.2MnO3−δCathodes

“…It is generally assumed that the TPB of SOFC electrodes, at which gas, electrode and electrolyte phases are simultaneously in contact, serve as the predominant site for the electrochemical reactions. 3 In this sense, various fabrication techniques have been investigated to obtain increased TPB lengths: (i) nanostructures LSM cathodes, including nanoparticles, nanofibers and thin films; [10][11][12][13][14][15][16] (ii) polymer templating methods to increase the porosity of the electrodes; [17][18][19] (iii) the infiltration of LSM into electrolyte backbones; [20][21][22] and (iv) composites of LSM with highly conductive materials, such as Bi 2 O 3-δ . [23][24][25][26] The preparation of electrodes via infiltration of a cation solution into a porous electrolyte backbone is one of the most effective methods used to increase the TPB area and to improve the cathode efficiency at lower temperature, especially in lab-scale research.…”

La-doped BaFeO3−δ perovskite as a cobalt-free oxygen reduction electrode for solid oxide fuel cells with oxygen-ion conducting electrolyte

“…The activity of an electrode is closely related to its material composition, lattice structure, physic-chemical properties, and morphologic structure. [6][7][8] Conventional oxygen reduction electrode in high-temperature SOFCs is La 0.8 Sr 0.2 MnO 3Àd (LSM), which has a perovskite-type lattice structure and shows pure electronic conductivity with the value in range of 150-250 S cm À1 under the fuel cells operation conditions. 9,10 Limited by its negligible oxygen-ion conductivity, the oxygen reduction reaction (ORR) over the LSM electrode occurs mainly at the triple phase boundaries (TPBs), at which gas, electrode and electrolyte phases are simultaneously in contact.…”

Nanosphere Lithography: A Powerful Method for the Controlled Manufacturing of Nanomaterials

“…Most of the literature on spin coating of colloidal suspension is experimentally based. Even if recent papers are more detailed, spin coating protocols described in the literature are varied and sometimes imprecise [56][57][58]. Therefore a major goal for further progress in NSL is the development of experimental protocols to control the ordering of particles on solid substrates and to get large well-ordered structures.…”