Abstract
Abstract Hydrogen is considered an attractive alternative to fossil fuels, but only a small amount of it is produced from renewable energy, making it not such a clean energy carrier after all. Producing hydrogen through water electrolysis is promising, but using a cost-effective and high-performing catalyst that has long-term stability is still a challenge. This study exploits, for the first time, the potential of zinc oxide nanoparticles with diverse morphologies as catalysts for the electrocatalytic production of hydrogen from water. The morphology of the nanoparticles (wires, cuboids, spheres) was easily regulated by changing the concentration of sodium hydroxide, used as the shape controlling agent, during the synthesis. The spherical morphology exhibited the highest electrocatalytic activity at the lowest potential voltage. These spherical nanoparticles had the highest number of oxygen vacancies and lowest particle size compared to the other two morphologies, features directly linked to high catalytic activity. However, the nanowires were much more stable with repeated scans. Density-functional theory showed that the presence of oxygen vacancies in all three morphologies led to diminished band gaps, which is of catalytic interest.
Highlights
Hydrogen is considered as an attractive energy vector due to its high energy to mass ratio (120 MJ/kg) that can replace fossil fuel consumption meeting global energy demands
Their structural, morphological and chemical properties were thoroughly investigated by X-ray diffraction (XRD), small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS)
To the best of our knowledge, this is the first study to report the influence of the Zinc oxide (ZnO) morphology, particle size and oxygen vacancies on its electrocatalytic activity for hydrogen production via electrochemical water splitting
Summary
Hydrogen is considered as an attractive energy vector due to its high energy to mass ratio (120 MJ/kg) that can replace fossil fuel consumption meeting global energy demands. Is cost-effective, both in terms of the raw materials and synthesis method, and has high catalytic efficiency and long-term stability is vital for the establishment of the green hydrogen production For this purpose, the potential of zinc oxide nanoparticles to be used as catalysts for the HER is exploited. Compared with other sol–gel methods, this approach is cost-effective, simple, and reproduced, and can be used to effectively control the morphology to create well-defined ZnO nanoparticles that are uniform in size Their structural, morphological and chemical properties were thoroughly investigated by X-ray diffraction (XRD), small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). To the best of our knowledge, this is the first study to report the influence of the ZnO morphology, particle size and oxygen vacancies on its electrocatalytic activity for hydrogen production via electrochemical water splitting
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