In this work, we present Co₃O₄ quantum dots (QDs) as a highly efficient and stable oxygen evolution reaction (OER) catalyst at neutral pH. The Co₃O₄ QDs with a mean size of 5 nm were synthesized by reacting cobalt acetate with benzyl alcohol in the presence of ammonia under reflux conditions. The as-synthesized Co₃O₄ QDs show extraordinary water oxidation activity with onset overpotential as low as 398 mV and mass activity as high as 567 A/g (at 1.75 V vs RHE) in a 0.2 M phosphate buffer electrolyte (pH ∼7), which are among the most efficient Earth-abundant OER catalysts at neutral pH reported in the literature, reaching a stable current density of 10 mA/cm² at an overpotential of ∼490 mV with a Tafel slope of 80 mV/decade. Through in-depth investigations by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, the high spin Co²⁺ and Co³⁺ cations on the surface of Co₃O₄ QDs were found to be important to promote the OER kinetics at neutral pH.

中文翻译：

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高自旋态促进中性pH下尖晶石型氧化钴中水的氧化催化作用

在这项工作中，我们提出了Co ₃ O ₄量子点（QDs）作为在中性pH值下高效且稳定的析氧反应（OER）催化剂。通过使乙酸钴与苯甲醇在氨气存在下于回流条件下反应，合成了平均粒径为5 nm的Co ₃ O ₄ QD。合成后的Co ₃ O ₄ QD在0.2 M磷酸盐缓冲电解质（pH约为7）中表现出非凡的水氧化活性，起始超电势低至398 mV，质量活性高达567 A / g（相对RHE为1.75 V）。 ），是文献中报道的在中性pH值下最有效的富含地球的OER催化剂之一，达到10 mA / cm ²的稳定电流密度在约490 mV的超电势下，Tafel斜率为80 mV /十倍。通过X射线光电子能谱和X射线吸收能谱的深入研究，发现Co ₃ O ₄ QDs表面的高自旋Co ²⁺和Co ³⁺阳离子对于促进中性OER动力学很重要。 pH值