I. Poimenidis, N. Papakosta, P. Loukakos, G. Marnellos, M. Konsolakis
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引用次数: 0
摘要
用于氧进化反应(OER)的非贵金属电催化剂最近受到了特别关注。本研究采用简便的一步电沉积法在泡沫镍(NF)电极上原位合成了硫化钴纳米结构。通过分别使用 Co(NO3)2-6 H2O 和 CH4N2S 作为 Co 和 S 前驱体,首次系统地研究了 Co/S 摩尔比对镍基 OER 电极的结构、形态和电化学特性的影响。等摩尔 Co:S 比例(1:1)的电极性能最佳,而富含硫或 Co 的电极性能较差。尤其是含有 Co/S(1:1)的 CoxSy@NF 电极,在 10 mA cm-2 时的过电位值最低(0.28 V),塔菲尔斜率为 95 mV dec-1,此外还具有 10.7 mF cm-2 的高双层电容(CDL)。电化学阻抗光谱(EIS)测量证实了 Co/S 比对电荷转移反应速率的关键影响,Co:S 摩尔比为 1:1 时,电荷转移反应速率最大。此外,还进行了场发射扫描电子显微镜 (FE-SEM)、X 射线衍射 (XRD) 和 X 射线荧光 (XRF),以深入了解 Co/S 比对电极结构和形态特征的影响。值得注意的是,具有等摩尔 Co:S 比率的 CoxSy@NF 电催化剂呈现出三维花状纳米片形态,提供了更大的电化学活性表面积(ESCA)并改善了 OER 动力学。
Highly Efficient Cobalt Sulfide Heterostructures Fabricated on Nickel Foam Electrodes for Oxygen Evolution Reaction in Alkaline Water Electrolysis Cells
Non-noble metal electrocatalysts for the oxygen evolution reaction (OER) have recently gained particular attention. In the present work, a facile one-step electrodeposition method is applied in situ to synthesize cobalt sulfide nanostructures on nickel foam (NF) electrodes. For the first time, a systematic study is carried out on the impact of the Co/S molar ratio on the structural, morphological, and electrochemical characteristics of Ni-based OER electrodes by employing Co(NO3)2·6 H2O and CH4N2S as Co and S precursors, respectively. The optimum performance was obtained for an equimolar Co:S ratio (1:1), whereas sulfur-rich or Co-rich electrodes resulted in an inferior behavior. In particular, the CoxSy@NF electrode with Co/S (1:1) exhibited the lowest overpotential value at 10 mA cm−2 (0.28 V) and a Tafel slope of 95 mV dec−1, offering, in addition, a high double-layer capacitance (CDL) of 10.7 mF cm−2. Electrochemical impedance spectroscopy (EIS) measurements confirmed the crucial effect of the Co/S ratio on the charge-transfer reaction rate, which is maximized for a Co:S molar ratio of 1:1. Moreover, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were conducted to gain insights into the impact of the Co/S ratio on the structural and morphological characteristics of the electrodes. Notably, the CoxSy@NF electrocatalyst with an equimolar Co:S ratio presented a 3D flower-like nanosheet morphology, offering an increased electrochemically active surface area (ESCA) and improved OER kinetics.