Abstract

Mixed transition-metals oxide electrocatalysts have shown huge potential for electrochemical water oxidation due to their earth abundance, low cost and excellent electrocatalytic activity. Here we present Co–Fe–B–O coatings as oxygen evolution catalyst synthesized by Pulsed Laser Deposition (PLD) which provided flexibility to investigate the effect of morphology and structural transformation on the catalytic activity. As an unusual behaviour, nanomorphology of 3D-urchin-like particles assembled with crystallized CoFe₂O₄ nanowires, acquiring high surface area, displayed inferior performance as compared to core–shell particles with partially crystalline shell containing boron. The best electrochemical activity towards water oxidation in alkaline medium with an overpotential of 315 mV at 10 mA/cm² along with a Tafel slope of 31.5 mV/dec was recorded with core–shell particle morphology. Systematic comparison with control samples highlighted the role of all the elements, with Co being the active element, boron prevents the complete oxidation of Co to form Co³⁺ active species (CoOOH), while Fe assists in reducing Co³⁺ to Co²⁺ so that these species are regenerated in the successive cycles. Thorough observation of results also indicates that the activity of the active sites play a dominating role in determining the performance of the electrocatalyst over the number of adsorption sites. The synthesized Co–Fe–B–O coatings displayed good stability and recyclability thereby showcasing potential for industrial applications.

Graphic Abstract

中文翻译：

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脉冲激光沉积碱性水氧化沉积Co-Fe-B-O薄膜的形貌和元素研究：与吸附过程相比，电荷交换效率是主要因素

摘要

混合过渡金属氧化物电催化剂由于其土壤丰富，低成本和出色的电催化活性而显示出巨大的电化学水氧化潜力。在这里，我们介绍了通过脉冲激光沉积（PLD）合成的Co-Fe-B-O涂层作为析氧催化剂，这为研究形态和结构转变对催化活性的影响提供了灵活性。作为不寻常的行为，与结晶的CoFe ₂ O ₄组装在一起的3D顽童状颗粒的纳米形态与具有硼的部分结晶壳的核壳颗粒相比，纳米线具有较高的表面积，表现出较差的性能。用核-壳颗粒形态记录了在10 mA / cm ^2时超电势为315 mV，Tafel斜率为31.5 mV / dec的碱性介质中对水氧化的最佳电化学活性。与对照样品的系统比较突出了所有元素的作用，其中Co是活性元素，硼阻止Co完全氧化形成Co ³⁺活性物质（CoOOH），而Fe有助于将Co ³⁺还原为Co ²⁺使这些物种在连续的循环中得以再生。对结果的透彻观察还表明，活性位点的活性在决定电催化剂在吸附位点数量上的性能方面起着主导作用。合成的Co–Fe–B–O涂层显示出良好的稳定性和可回收性，从而展示了工业应用的潜力。

图形摘要