石墨烯
过电位
电催化剂
氧化物
咪唑酯
材料科学
化学工程
电解质
碳化
催化作用
金属有机骨架
分解水
碳纤维
纳米技术
无机化学
化学
电极
电化学
复合数
有机化学
物理化学
复合材料
吸附
冶金
工程类
光催化
扫描电子显微镜
作者
Sampath Gayathri,Paulraj Arunkumar,Ranjith Bose,Akram Alfantazi,Jong Hun Han
标识
DOI:10.1016/j.cej.2021.131270
摘要
Designing unique metal–organic framework (MOF) precursors is crucial for the development of efficient metal-supported carbon-based electrocatalysts for the hydrogen evolution reaction (HER). Herein, the atypical role of graphene oxide (GO) in the morphology of 2D Co-based leaf-like zeolitic imidazolate framework (ZIF-Co-L) is reported. We demonstrated that GO regulated water accessibility in the ZIF reaction medium. The shape of GO-modified ZIF transformed from typical leaf-like (at GO contents of less than 40 wt%) to elongated hexagonal-shape (at GO contents of ≥ 40 wt%). This was attributed to the trapping of water molecules into the interlayers of GO. The water-deficient medium restricted crystal growth along the a direction of ZIF-Co-L and caused the formation of hexagonal shapes by distorting the water-driven hydrogen-bonding interactions between monodentate methylimidazole (mIm) in the ab direction and free mIm in the c direction. Furthermore, the leaf-like [email protected]%GO and hexagonal-shaped [email protected]%GO precursors were carbonized to Co-embedded N-doped-carbon/reduced GO (rGO) electrocatalysts, denoted as [email protected] and [email protected], respectively. The [email protected] catalyst (~3% rGO) presented fast kinetics and high durability (~10 h) in KOH electrolyte. Moreover, the overpotential of [email protected] at 10 mA cm−2 in the KOH electrolyte (220 mV) was lower than that of [email protected] (230 mV). This was ascribed to the lower ratio of Co-to-rGO contents in the [email protected] (~13% rGO) inhibiting its HER activity despite their excellent shape benefits of the ZIF precursor. The superior performance of [email protected] electrocatalysts was attributed to the unique shape features of ZIF precursor; abundant active sites; and synergistic effect of Co nanoparticles, N doping, and conducting carbon. The proposed synthesis approach offers promising prospects for the development of transition-metal-supported carbon-based catalysts from shape-variant MOF precursors for efficient electrochemical water splitting.
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