resumo
The development of efficient electrocatalysts for slow reaction of the oxygen evolution reaction (OER) is fundamental for viability of the electrochemical water splitting technologies. Here we report for the first time the synthesis of NiO/carbon hollow fibres (NiO-HF) by the Solution Blow Spinning (SBS) technique, and a study of their catalytic activity towards the OER in alkaline medium. The hollow fibres were obtained with ca. 300 nm in diameter consisting of agglomerated NiO nanoparticles with an average size of 50 nm which is close to the tubular wall thickness. The formation mechanism of the hollow structure was discussed. It was revealed that the carbon from polyenic branch of polyvinylpyrrolidone (PVP) resists the firing treatment and acts as an agglomerating agent, thus ensuring a conductive and percolating path between NiO nanoparticles along the fibres. A battery of electrochemical tests of NiO-HF supported by commercial Ni foam reveals excellent electrochemical activity for OER in 1 M KOH, in comparison with reference NiO nanoparticles (NiO-NP, diameter ca. 23 nm). NiO-HF attains an overpotential of 340 mV vs. RHE at a current density of 10 mA cm(-2), which is amongst the lowest values reported in the literature for undoped NiO. Chronopotentiometry reveals stable NiO-HF electrodes over 15 h under an electrolysis current of 25 mA cm(-2). Microscopic analysis shows that the fibrillar morphology is completely preserved after the electrolysis test. The remarkable performance of the NiO-HF catalyst is ascribed to the enhanced electronic conductivity resulting from the interpenetrating NiO-HF/carbon microstructure. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
palavras-chave
ELECTROSPUN NANOFIBERS; ENERGY-CONVERSION; CARBON NANOFIBERS; HIGHLY EFFICIENT; MFE2O4 M; OXIDE; NI; METAL; NANOPARTICLES; NANOSHEETS
categoria
Chemistry; Electrochemistry; Energy & Fuels
autores
Silva, VD; Simoes, TA; Loureiro, FJA; Fagg, DP; Figueiredo, FML; Medeiros, ES; Macedo, DA
nossos autores
agradecimentos
The authors acknowledge CNPq (447797/2014-0 and 311883/2016-8) and CAPES (Brazil) and the Foundation for Science and Technology Portugal, FCT, project grant PTDC CTM-ENE/6319/2014, UID/CTW50011/2013 and CENTRO-01-0145-FEDER-022083, IF/01344/2014/CP1222/CT0001, (IF/01174/2013, QREN, FEDER and COMPETE Portugal and the European Union for their financial support. Additional support and funding from projects CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTW50011/2013), and UniRCell POCI-01-0145-FEDER-016422 (Ref. SAICTPAC/0032/2015), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement, are also acknowledged. Vinicius D. Silva and Thiago A. Similes thank CAPES for their master and postdoctoral grants. Francisco J. A. Loureiro acknowledges FCT grant PD/BDE/114353/2016. We wish to thank Prof. Rubens Maribondo do Nascimento (UFRN) and Prof. Sandro Marden Torres (UFPB) for FESEM and XRD analyses, respectively, and to Prof. Rik Brydson (Leeds) for debating the XPS results.