Co-Ni bi-metallic thin films with different stoichiometries have been deposited by magnetron co-sputtering technique on Ni foam (NF), Si and carbon paper substrates. The structural and morphological characterisations of these films have been done by X-ray diffraction, X-ray absorption spectroscopy and Field Emission Scanning Electron Microscope measurements. The performances of these films for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have been evaluated through electrochemical measurements like Linear Sweep Voltammetry, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy measurements. X ray absorption near edge spectroscopy measurements have also been carried out during HER and OER to decipher the redox reaction mechanisms. It has been observed that the HER and OER performance of all the Co Ni bi-metallic thin films on NF are found to be better than that of bare NF. The CoNi sample with composition of 58.7 % Co and 41.3 % Ni shows the best catalytic activity and stability towards HER and OER reactions. Though the HER activity is not the best but is comparable to many results reported in the literature, however the catalyst shows excellent OER activity with overpotential of 214 mV for 10 mA/cm current density. This is much better than that of the OER benchmark catalyst RuO and most of those reported in the literature. The OER is kinetically slower than HER and requires more overpotential, hence a significant improvement in the catalytic OER activity will definitely enhance the overall water splitting activity and hydrogen production efficiency. Thus the Co-Ni bi-metallic catalyst prepared by an easily scalable and highly reproducible magnetron co-sputtering technique has significant potential to emerge out as a technologically viable water splitting catalyst.

中文翻译：

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用于碱性析氢和析氧反应的Co-Ni共溅射沉积双金属薄膜催化剂


采用磁控共溅射技术在泡沫镍（NF）、硅和碳纸基材上沉积了不同化学计量的钴镍双金属薄膜。这些薄膜的结构和形态表征已通过 X 射线衍射、X 射线吸收光谱和场发射扫描电子显微镜测量完成。这些薄膜的析氢反应 (HER) 和析氧反应 (OER) 性能已通过线性扫描伏安法、循环伏安法和电化学阻抗谱测量等电化学测量进行了评估。在 HER 和 OER 过程中还进行了 X 射线吸收近边光谱测量，以破译氧化还原反应机制。据观察，NF 上所有 Co Ni 双金属薄膜的 HER 和 OER 性能均优于裸 NF。成分为 58.7% Co 和 41.3% Ni 的 CoNi 样品对 HER 和 OER 反应表现出最佳的催化活性和稳定性。虽然 HER 活性不是最好的，但与文献报道的许多结果相当，但该催化剂显示出优异的 OER 活性，在 10 mA/cm 电流密度下过电势为 214 mV。这比 OER 基准催化剂 RuO 和文献中报道的大多数催化剂要好得多。 OER在动力学上比HER更慢并且需要更多的过电势，因此催化OER活性的显着提高肯定会提高整体水分解活性和产氢效率。 因此，通过易于扩展和高度可重复的磁控共溅射技术制备的Co-Ni双金属催化剂具有作为技术上可行的水分解催化剂的巨大潜力。