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<p>Cobalt nanoparticles with controlled morphology were synthesized via a tunable heating-rate approach and evaluated for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysis. Cyclic voltammetry studies revealed that the nanoparticles remain electrochemically stable up to –1.5&#xa0;V, with well-defined cathodic and anodic redox peaks corresponding to the Co2⁺/Co redox couple. Among the synthesized samples, those prepared at the lowest heating rate (5&#xa0;°C&#xa0;h⁻1) exhibited superior catalytic activity, achieving a maximum current of 4.31&#xa0;mA and a current density of 215&#xa0;mA&#xa0;cm⁻2 at –1.5&#xa0;V. The onset potentials for HER were –0.798, –0.808, and –0.814&#xa0;V versus Ag/AgCl for heating rates of 5, 25, and 250&#xa0;°C&#xa0;h⁻1, respectively, with corresponding overpotentials at 10&#xa0;mA&#xa0;cm⁻2 of –0.870, –0.902, and –0.942&#xa0;V. These results surpass the performance of bulk cobalt and are comparable with reported cobalt-based electrocatalysts. Long-term electrochemical stability was demonstrated over 250 continuous cycles without significant loss of activity. Post-electrolysis structural characterization confirmed that the nanoparticles retained their crystalline monophasic structure and predominantly spherical morphology, with minor surface oxidation observed. The enhanced HER performance is attributed to the higher specific surface area and favorable nanoparticle alignment achieved at lower heating rates, highlighting the critical role of synthesis parameters in tuning electrochemical activity. Overall, this study demonstrates that rationally engineered cobalt nanostructures offer a promising, cost-effective route for high-performance HER and OER electrocatalysis, providing valuable insights for the development of sustainable water-splitting technologies.</p> Graphical Abstract <p>Synthesis of Co metal nanoparticles of different size having excellent electrocatalytic property with high stability</p> <p></p>

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Investigation of growth mechanism for non-precious Co nanostructures as highly efficient electrocatalysts for hydrogen and oxygen evolution reaction

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  • 发表日期：

    2026年3月19日

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  • Bharat Kumar

摘要

Cobalt nanoparticles with controlled morphology were synthesized via a tunable heating-rate approach and evaluated for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysis. Cyclic voltammetry studies revealed that the nanoparticles remain electrochemically stable up to –1.5 V, with well-defined cathodic and anodic redox peaks corresponding to the Co2⁺/Co redox couple. Among the synthesized samples, those prepared at the lowest heating rate (5 °C h⁻1) exhibited superior catalytic activity, achieving a maximum current of 4.31 mA and a current density of 215 mA cm⁻2 at –1.5 V. The onset potentials for HER were –0.798, –0.808, and –0.814 V versus Ag/AgCl for heating rates of 5, 25, and 250 °C h⁻1, respectively, with corresponding overpotentials at 10 mA cm⁻2 of –0.870, –0.902, and –0.942 V. These results surpass the performance of bulk cobalt and are comparable with reported cobalt-based electrocatalysts. Long-term electrochemical stability was demonstrated over 250 continuous cycles without significant loss of activity. Post-electrolysis structural characterization confirmed that the nanoparticles retained their crystalline monophasic structure and predominantly spherical morphology, with minor surface oxidation observed. The enhanced HER performance is attributed to the higher specific surface area and favorable nanoparticle alignment achieved at lower heating rates, highlighting the critical role of synthesis parameters in tuning electrochemical activity. Overall, this study demonstrates that rationally engineered cobalt nanostructures offer a promising, cost-effective route for high-performance HER and OER electrocatalysis, providing valuable insights for the development of sustainable water-splitting technologies.

Graphical Abstract

Synthesis of Co metal nanoparticles of different size having excellent electrocatalytic property with high stability