Copper Cobalt Sulfide Nanosheets Realizing a Promising Electrocatalytic Oxygen Evolution Reaction
Copper Cobalt Sulfide Nanosheets Realizing a Promising Electrocatalytic Oxygen Evolution Reaction
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DOI：
10.1021/acscatal.7b01831
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发表时间：
2017-09-01
期刊：
影响因子：
12.9
通讯作者：
Deka, Sasanka
中科院分区：
文献类型：
--
作者：
Chauhan, Meenakshi;Reddy, Kasala Prabhakar;Deka, Sasanka
纳米结构的CuCo 2S 4，混合金属硫尖晶石，被发现是一个基准电催化剂的析氧反应（OER）在这项研究中具有低过电位，低塔菲尔斜率，高耐久性，和高周转频率（TOF）在较低的质量负载。CuCo 2S 4的纳米片由水热合成方法实现，其中发现片的平均厚度在815 nm的范围内。聚集的纳米片形成高度开放的分级结构。当用作电催化剂时，CuCo 2S 4纳米片在10 mA cm（2）电流密度下提供310 mV的超电势值，在1 M KOH电解质中进行10000次测量循环时保持一致。计时电流法研究表明，在10 mV s（-1）扫描速率下持续12 h的氧气释放量不变，活性无任何降解。此外，计算出的CuCo 2S 4电催化剂的质量活性被发现是14.29 A/g，并在310 mV下在0.7 mg cm（-2）的质量负载下提供0.1431 s（-1）的TOF值。为了比较，Co 3S 4和Cu0.5Co2.5S4的纳米结构已经使用与CuCo 2S 4类似的方法合成。当与这三种硫尖晶石和标准IrO 2之间的OER活性相比时，CuCo 2S 4纳米片在相同的质量负载（0.7 mg/cm（-2））下提供最高的OER活性。广泛的X射线光电子能谱和电子顺磁共振分析的机制研究表明，引入铜到Co 3S 4晶格增强氧的演变和动力学提供Cu 2+网站的实用吸附的OH，O，和OOH反应物种，也通过提供一个高度活跃的高自旋状态的八面体Co 3 + OER催化。
Nanostructured CuCo2S4, a mixed metal thiospinel, is found to be a benchmark electrocatalyst for oxygen evolution reaction (OER) in this study with a low overpotential, a low Tafel slope, a high durability, and a high turnover frequency (TOF) at lower mass loadings. Nanosheets of CuCo2S4 are realized from a hydrothermal synthesis method in which the average thickness of the sheets is found to be in the range of 815 nm. Aggregated nanosheets form a highly open hierarchical structure. When used as an electrocatalyst, CuCo2S4 nanosheets offer an overpotential value of 310 mV at a 10 mA cm(2) current density, which remains consistent for 10000 measured cycles in a 1 M KOH electrolyte. A chronoamperometric study reveals constant oxygen evolution for 12 h at a 10 mV s(-1) scan rate without any degradation of the activity. Furthermore, the calculated mass activity of the CuCo2S4 electrocatalyst is found to be 14.29 A/g and to afford a TOF value of 0.1431 s(-1) at 310 mV at a mass loading of 0.7 mg cm(-2). For comparison, nanostructures of Co3S4 and Cu0.5Co2.5S4 have been synthesized using a similar method followed for CuCo2S4. When compared to the OER activities among these three thiospinels and standard IrO2, CuCo2S4 nanosheets offered the highest OER activities at the same mass loading (0.7 mg/cm(-2)). Extensive X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses for a mechanistic study reveal that introduction of Cu into the Co3S4 lattice enhances the oxygen evolution and kinetics by offering Cu2+ sites for utilitarian adsorption of OH, O, and OOH reactive species and also by offering a highly active high-spin state of octahedral Co3+ for OER catalysis.