Electrocatalytic Water Splitting with Ruthenium Nanoparticles

Abstract

The study of nanoparticulated systems for the hydrogen evolution (HER) and oxygen evolution (OER) reactions allows to rationally design new catalysts that enhance the water splitting process for obtaining H2, and thus making it a suitable alternative to fossil fuels as energy carriers. Nowadays Pt and Ir are the leading metals in HE and OE catalysts, respectively, but a huge effort is being devoted to understand the mechanistic pathways that rule both semi-reactions in order to transfer the knowledge to other metals which can be more abundant and thus cheaper. Ru appears as a feasible alternative to deeply explore the reaction steps involved in the process, because it is a highly-versatile metal which shows similar activities than Pt/Ir and which can be studied by a wide range of analytical techniques as a result of its properties. In addition, Ru is four times cheaper than the state-of-the-art Pt. This PhD work aims to develop Ru-based nanocatalysts for both HER and OER, and study the characteristics that induce a specific catalytic response. The use of the organometallic approach as synthetic methodology allows to finely control the properties of the NPs, e.g. size, surface environment, dispersion, etc. In this synthetic procedure, organic ligands can be added as stabilizing agents to halt the nucleation of metal atoms leading to the formation of the nanosized systems. These ligands can alter the chemical properties of the surface of the nanoparticles, a key feature in the catalytic processes. This methodology allows as well the preparation of metal nanoparticles onto the surface of solid supports, e.g. carbon nano-tubes, fibers, metal oxides, MOFs, etc. The organometallic approach was first developed in our group around three decades ago, and today its wide use by the global scientific community has brought a large knowledge on different nanometric systems. The development of precisely controlled nanocatalysts for their application in challenging catalysis like the production of H2 by water-splitting lies among our research interests. To sum up, the synthesis of Ru-NPs and their evaluation as catalysts for the HER and OER are described, aiming to understand the factors ruling the catalytic steps on the surface of the particles, to be able to rationally design new catalysts that make the water splitting process efficient enough to replace fossil fuels by H2.

Date of Award	11 Jul 2018
Original language	English
Supervisor	Jordi García-Antón Aviñó (Co-director), Xavier Sala Roman (Co-director) & Karine Philippot (Co-director)