The development of a less expensive yet outstanding electrocatalyst in terms of activity and stability for the oxygen evolution reaction (OER) working in a universal pH range still remains challenging. Most of the highly active expensive electrocatalyts work in a single pH. Therefore, the development of a low cost electrocatalyst, which fulfils the above-mentioned requirements, is highly needed. Here, we report the development of Co₃S₄ hollow nanoparticles using a one-step hot injection method, and we modified them for superior electrocatalytic OER activity and stability in the entire pH range (alkaline, neutral, and acidic). Activated carbon supported Co₃S₄ hollow nanoparticles exhibit remarkable OER activity (overpotential, η = 0.27 V in 1.0 M KOH; 0.33 V in 0.5 M H₂SO₄; 0.37 V in 1.0 M phosphate buffer) and offer maximal cycling stability for more than 24–48 h (>10 000 cycles) with no loss in the magnitude of current density (10 mA/cm²). High spin states of Co²⁺ and Co³⁺ and their large spin–orbit interactions (as indicated by XPS and EPR studies) related to oxygen surface exchange mechanism are proposed to account for the observed high electrocatalytic activity at all pH levels.

中文翻译：

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空心钴硫化物纳米颗粒：鲁棒和低成本的pH值通用氧气析出电催化剂

就在通用pH范围内进行的析氧反应（OER）的活性和稳定性而言，开发一种价格较低廉但出色的电催化剂仍然具有挑战性。大多数高活性，昂贵的电催化剂都在单个pH下工作。因此，迫切需要开发满足上述要求的低成本电催化剂。在这里，我们报告了使用一步热注射方法开发的Co ₃ S ₄空心纳米颗粒，并对它们进行了改性，使其在整个pH范围（碱性，中性和酸性）中均具有出色的电催化OER活性和稳定性。活性炭负载的Co ₃ S ₄中空纳米颗粒具有显着的OER活性（过电势，在1.0 M KOH中η= 0.27 V；在0.5 MH ₂ SO ₄中为0.33 V ；在1.0 M磷酸盐缓冲液中为0.37 V），并提供超过24–48 h（> 10的最大循环稳定性） 000个周期），而电流密度（10 mA / cm ²）的大小没有损失。提出了与氧表面交换机制有关的Co ²⁺和Co ^3+的高自旋态以及它们的大自旋轨道相互作用（如XPS和EPR研究所示），以解释在所有pH值下观察到的高电催化活性。