CONICET | Buscador de Institutos y Recursos Humanos

The use of earth-abundant materials for designing efficient and stable electrocatalysts is of paramount importance tofacilitate large-scale production of hydrogen. In this work we developed a new series of electrodes based on Nisemiconductorcomposites (Ni|SC) that are easy to synthesize (binder-free, economic and readily scalable method ofsynthesis), highly stable and active towards electrochemical hydrogen production under alkaline conditions. We showed thedirect electrodeposition of composites (Ni|SC) from nickel-Watts plating baths modified by the addition of Nb2O5, Nb3(PO4)5,Bi2O3 and WO3 semiconductor particles. The electrodes were characterized by different techniques (electron and confocalmicroscopy, X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, among others) before and after theirelectrochemical evaluation as catalysts for hydrogen evolution from water. In order to gain insights into their structureactivityrelationship, the materials were also characterized by means of electrochemical analyses, i.e., cyclic voltammetry,chronoamperometry and electrochemical impedance spectroscopy. All catalysts have onset potential values around -1.1 Vvs SCE and similar Tafel slopes (ca. 120 mV dec-1) corresponding to the Volmer reaction as the rate determining step of thereaction. These catalysts show an increase of up to 115% (for Ni|WO3) of hydrogen production current compared toconventional Ni catalysts; in most cases preserving great chemical and structural stability after short ageing under alkalineconditions. The composite catalysts were synthesized on low-cost nickel-plated stainless-steel supports, which make themexcellent alternatives for replacing massive nickel electrodes in conventional alkaline electrolyzers.

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