Bernicke Michael, Ortel Erik, Reier Tobias, Bergmann Arno, Ferreira de Araujo Jorge, Strasser Peter, Kraehnert Ralph
Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 124, 10623 Berlin (Germany).
Division 6.8 Surface Analysis and Interfacial Chemistry, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 44-46, 12203 Berlin (Germany).
ChemSusChem. 2015 Jun 8;8(11):1908-15. doi: 10.1002/cssc.201402988. Epub 2015 May 8.
Iridium oxide is the catalytic material with the highest stability in the oxygen evolution reaction (OER) performed under acidic conditions. However, its high cost and limited availability demand that IrO2 is utilized as efficiently as possible. We report the synthesis and OER performance of highly active mesoporous IrO2 catalysts with optimized surface area, intrinsic activity, and pore accessibility. Catalytic layers with controlled pore size were obtained by soft-templating with micelles formed from amphiphilic block copolymers poly(ethylene oxide)-b-poly(butadiene)-b-poly(ethylene oxide). A systematic study on the influence of the calcination temperature and film thickness on the morphology, phase composition, accessible surface area, and OER activity reveals that the catalytic performance is controlled by at least two independent factors, that is, accessible surface area and intrinsic activity per accessible site. Catalysts with lower crystallinity show higher intrinsic activity. The catalyst surface area increases linearly with film thickness. As a result of the templated mesopores, the pore surface remains fully active and accessible even for thick IrO2 films. Even the most active multilayer catalyst does not show signs of transport limitations at current densities as high as 75 mA cm(-2) .
氧化铱是在酸性条件下进行析氧反应（OER）时稳定性最高的催化材料。然而，其高成本和有限的可用性要求尽可能高效地利用IrO₂。我们报道了具有优化表面积、本征活性和孔可及性的高活性介孔IrO₂催化剂的合成及其OER性能。通过用两亲性嵌段共聚物聚（环氧乙烷）-b-聚（丁二烯）-b-聚（环氧乙烷）形成的胶束进行软模板法制备了具有可控孔径的催化层。对煅烧温度和膜厚度对形态、相组成、可及表面积和OER活性的影响进行的系统研究表明，催化性能至少受两个独立因素控制，即可及表面积和每个可及位点的本征活性。结晶度较低的催化剂显示出较高的本征活性。催化剂表面积随膜厚度线性增加。由于模板化介孔的存在，即使对于厚的IrO₂膜，孔表面仍保持完全活性且可及。即使是活性最高的多层催化剂在高达75 mA cm⁻²的电流密度下也没有显示出传输限制的迹象。
