State Key Laboratory of Chem/Bio-Sensing and Chemometrics, Provincial Hunan Key Laboratory for Graphene Materials and Devices, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.
School of Chemistry, University of Manchester, Manchester, M13 9PL, UK.
Adv Mater. 2017 Aug;29(30). doi: 10.1002/adma.201701546. Epub 2017 Jun 7.
An earth-abundant and highly efficient electrocatalyst is essential for oxygen evolution reaction (OER) due to its poor kinetics. Layered double hydroxide (LDH)-based nanomaterials are considered as promising electrocatalysts for OER. However, the stacking structure of LDHs limits the exposure of the active sites. Therefore, the exfoliation is necessary to expose more active sites. In addition, the defect engineering is proved to be an efficient strategy to enhance the performance of OER electrocatalysts. For the first time, this study prepares ultrathin CoFe LDHs nanosheets with multivacancies as OER electrocatalysts by water-plasma-enabled exfoliation. The water plasma can destroy the electrostatic interactions between the host metal layers and the interlayer cations, resulting in the fast exfoliation. On the other hand, the etching effect of plasma can simultaneously and effectively produce multivacancies in the as-exfoliated ultrathin LDHs nanosheets. The increased active sites and the multivacancies significantly contribute to the enhanced electrocatalytic activity for OER. Compared to pristine CoFe LDHs, the as-exfoliated ultrathin CoFe LDHs nanosheets exhibit excellent catalytic activity for OER with a ultralow overpotential of only 232 mV at 10 mA cm and possesses outstanding kinetics (the Tafel slope of 36 mV dec ). This work provides a novel strategy to exfoliate LDHs and to produce multivacancies simultaneously as highly efficient electrocatalysts for OER.
由于动力学性能较差，对于析氧反应（OER）而言，一种丰富且高效的电催化剂至关重要。基于层状双氢氧化物（LDH）的纳米材料被认为是 OER 的一种很有前途的电催化剂。然而，LDHs 的堆叠结构限制了活性位点的暴露。因此，必须进行剥离以暴露更多的活性位点。此外，缺陷工程已被证明是增强 OER 电催化剂性能的有效策略。本研究首次通过水等离子体引发的剥离，制备了具有多空位的超薄 CoFe LDHs 纳米片作为 OER 电催化剂。水等离子体可以破坏主体金属层与层间阳离子之间的静电相互作用，从而实现快速剥离。另一方面，等离子体的刻蚀效应可以同时有效地在剥离得到的超薄 LDHs 纳米片中产生多空位。增加的活性位点和多空位显著提高了 OER 的电催化活性。与原始的 CoFe LDHs 相比，剥离得到的超薄 CoFe LDHs 纳米片具有出色的 OER 催化活性，仅需 232 mV 的超低过电位即可达到 10 mA cm 的电流密度，并且具有出色的动力学性能（塔菲尔斜率为 36 mV dec ）。这项工作为 LDHs 的剥离和同时产生多空位提供了一种新策略，为 OER 高效电催化剂的制备提供了新的思路。
