School of Chemical Engineering, The University of Adelaide, Adelaide, SA 5005, Australia.
Nanoscale. 2019 Feb 21;11(8):3599-3605. doi: 10.1039/c8nr09680e.
2D metal-organic frameworks (MOFs) are widely regarded as promising electrocatalysts for the oxygen evolution reaction (OER). This results from their inherent properties such as a large portion of surface coordinatively unsaturated metal atoms, rapid mass transfer and enhanced conductivity. However, 2D MOFs have a strong tendency to aggregate, which severely limits their potential application in the OER. Here, novel 2D Ni-BDC/Ni(OH)2 (BDC stands for 1,4-benzenedicarboxylate, C8H4O4) hybrid nanosheets are synthesized via a facile sonication-assisted solution method. Because of the rational material design, the large surface area of Ni-BDC is maintained. Significantly, after coupling, the electronic structure of Ni atoms in the Ni(OH)2 component is well modified, leading to the generation of Ni cations with higher oxidation states, which are desirable for the OER. As-prepared Ni-BDC/Ni(OH)2 exhibits high activity, favorable kinetics and strong durability towards the OER. Specifically, the OER current density of Ni-BDC/Ni(OH)2 is 82.5 mA cm-2 at 1.6 V versus a reversible hydrogen electrode (RHE), which is significantly greater than those of Ni-BDC (5.5 times), Ni(OH)2 (20.6 times) and Ir/C (3.0 times). Moreover, the sonication-assisted method developed in this work can be readily adapted for the preparation of various 2D MOF-based hybrid functional materials.
二维金属-有机骨架（MOFs）被广泛认为是氧气析出反应（OER）的有前途的电催化剂。这是由于其固有特性，如大量表面配位不饱和金属原子、快速传质和增强的导电性。然而，二维 MOFs 有强烈的聚集倾向，这严重限制了它们在 OER 中的潜在应用。在此，通过简便的超声辅助溶液法合成了新型二维 Ni-BDC/Ni(OH)2（BDC 代表 1,4-苯二甲酸，C8H4O4）杂化纳米片。由于合理的材料设计，Ni-BDC 的大表面积得以保持。值得注意的是，耦合后，Ni(OH)2 组分中 Ni 原子的电子结构得到了很好的修饰，导致生成了具有更高氧化态的 Ni 阳离子，这对于 OER 是理想的。所制备的 Ni-BDC/Ni(OH)2 对 OER 表现出高活性、有利的动力学和强耐久性。具体而言，Ni-BDC/Ni(OH)2 在 1.6 V 相对于可逆氢电极（RHE）的 OER 电流密度为 82.5 mA cm-2，明显大于 Ni-BDC（5.5 倍）、Ni(OH)2（20.6 倍）和 Ir/C（3.0 倍）。此外，本工作中开发的超声辅助方法可以很容易地适应各种二维 MOF 基杂化功能材料的制备。
