Nunes, Marta S.Fernandes, Diana M.Morales, M. V.Rodríguez Ramos, InmaculadaGuerrero Ruíz, Antonio RicardoFreire, Cristina2024-11-072024-11-072020-11-01Marta Nunes, Diana M. Fernandes, M.V. Morales, I. Rodríguez-Ramos, A. Guerrero-Ruiz, Cristina Freire, Cu and Pd nanoparticles supported on a graphitic carbon material as bifunctional HER/ORR electrocatalysts, Catalysis Today, Volume 357, 2020, Pages 279-290, ISSN 0920-5861, https://doi.org/10.1016/j.cattod.2019.04.0430920-5861 | eISSN 1873-4308https://doi.org/10.1016/j.cattod.2019.04.043https://hdl.handle.net/20.500.14468/24279The registered version of this article, first published in “Catalysis Today, Volume 357", is available online at the publisher's website: Elsevier, https://doi.org/10.1016/j.cattod.2019.04.043 La versión registrada de este artículo, publicado por primera vez en “Catalysis Today, Volume 357", está disponible en línea en el sitio web del editor: Elsevier, https://doi.org/10.1016/j.cattod.2019.04.043The development of efficient, available and robust substitutes for the Pt-based electrocatalysts is very important for a sustainable energetic future. Herein, we report a series of composites based on Cu, Pd and Cu-Pd nanoparticles (NPs) supported on high surface area graphite (HSAG), as electrocatalysts for the energy-related reduction reactions – oxygen reduction (ORR) and hydrogen evolution (HER) reactions. All the composites showed interesting ORR electrocatalytic activities in alkaline medium. The Pd/HSAG and Cu-Pd/HSAG composites exhibited the most promising performances, with onset potentials of 0.84 and 0.91 V and current densities of jL, 0.3 V, 1600 rpm=−3.5 and −4.2 mA cm−2, respectively. All the composites showed selectivity for the 4-electron process and Tafel slopes in the range 48–77 mV dec−1. The metal/HSAG composites revealed a great tolerance to methanol and moderate electrochemical stability. In highly acidic medium (0.5 mol dm−3 H2SO4, pH=0.3) only the Cu-Pd/HSAG and Pd/HSAG electrocatalysts presented electrocatalytic activity toward HER, with relative low overpotentials (η10=0.145 and 0.063 V, respectively), small Tafel slopes (75 and 42 mV dec−1) and similar exchange current densities (0.43 and 0.57 mA cm−2). These electrocatalysts also showed moderate electrochemical stability, in particular Cu-Pd/ HSAG for which overpotential only changed between 0.033 and 0.038 V for j=40mAcm−2. The results showed that only small loading of Pd NPs (1 wt.% Pd) was able to improve significantly the ORR/ HER electrocatalytic activity, which is a very important outcome to rationalize the design of efficient and costeffective electrocatalysts in future.eninfo:eu-repo/semantics/openAccess23 Química::2303 Química inorgánicaartículoOxygen reduction reactionHydrogen evolution reactionPalladium nanoparticlesCopper nanoparticlesBifunctionality