Hydrogen evolution reaction (HER) has been identified as a sustainable and environment friendly technology for a wide range of energy conversion and storage applications. The big barrier in realizing this green technology requires a highly efficient, earth-abundant, and low-cost electrocatalyst for HER. Various HER catalysts have been designed and reported, still, their performance is not up to the mark of Pt. Among them, cobalt-based, especially cobalt disulfide (CoS₂) has shown significant HER activity and found suitable candidature for HER due to its low cost, simple to prepare, and exhibits good stability. Herein, we synthesized various nanostructured materials including pure CoS₂, Co₃O₄ and their composites by wet chemical methods and found them active for HER. The scanning electron microscopy (SEM) has revealed a morphology of composite as a mixture of nanowires and round shape spherical nanoparticles with several microns in dimension. The X-ray diffraction (XRD) confirmed the cubic phase of CoS₂ and cubic phase of Co₃O₄ in the composite materials. The chemical deposition of CoS₂ onto Co₃O₄ has tailored the HER activity of CoS₂@Co₃O₄ composite material. Two CoS₂@Co₃O₄ composite materials were produced with varying amounts of Co₃O₄ and labeled as samples 1 and 2. The Co₃O₄ reduced the adsorption energy for hydrogen, decreased the aggregation of CoS₂ and uplifted the stability of CoS₂@Co₃O₄ a composite material in alkaline media. Sample 1 requires an overpotential of 320 mV to reach a current density of 10 mA/cm² and it exhibits a Tafel slope of 42 mVdec⁻¹which is the key indicator for the fast HER kinetics on sample 1. The sample 1 is highly durable for 50 h and also it has excellent stability. The electrochemical impedance spectroscopy (EIS) revealed a small charge transfer resistance of 28.81 Ohms for the sample 1 with high capacitance double-layer value of 0.81 mF. EIS has supported polarization and Tafel slope results. Based on the partial physical characterization and the electrochemical results, the as-obtained sample 1 (CoS₂@Co₃O₄ composite material) will find potential applications in an extended range of energy conversion and storage devices owing to its low cost, high abundance, and excellent efficiency.

氢气析出反应（HER）被认为是一种可持续的，环境友好的技术，适用于各种能量转换和存储应用。实现这种绿色技术的最大障碍是需要高效，富含地球和低成本的HER电催化剂。已经设计并报道了多种HER催化剂，但是它们的性能还没有达到Pt的标准。其中，基于钴的，尤其是二硫化钴（CoS ₂）显示出显着的HER活性，并且由于其成本低，易于制备且显示出良好的稳定性而成为HER的合适候选者。在此，我们合成了包括纯CoS ₂，Co ₃ O ₄在内的各种纳米结构材料。和它们的复合物通过湿化学方法，发现它们对HER具有活性。扫描电子显微镜（SEM）揭示了复合物的形态，该复合物是纳米线和尺寸为几微米的圆形球形纳米粒子的混合物。X射线衍射（XRD）证实了复合材料中CoS _2的立方相和Co ₃ O _4的立方相。CoS ₂在Co ₃ O ₄上的化学沉积已调整了CoS ₂ @Co ₃ O ₄复合材料的HER活性。两个CoS ₂ @Co ₃ O ₄复合材料制作了具有不同量的Co ₃ ö ₄，并标记为样品1和2共同₃ Ô ₄降低了吸附能量为氢，降低服务等级的聚集₂和隆起的CoS的稳定性₂ @Co ₃ ö ₄在碱性介质中的复合材料。样品1需要320 mV的过电势才能达到10 mA / cm ²的电流密度，并且其Tafel斜率显示为42 mVdec ^-1这是样品1上快速HER动力学的关键指标。样品1具有50小时的高度耐用性，并且具有出色的稳定性。电化学阻抗谱（EIS）显示，样品1的电荷转移电阻小，为28.81欧姆，双层电容值为0.81 mF。EIS支持极化和Tafel斜率结果。根据部分物理特征和电化学结果，所获得的样品1（CoS ₂ @Co ₃ O ₄复合材料）因其低成本，高丰度而将在扩展的能量转换和存储设备中找到潜在的应用。 ，效率极高。