Huang Hao, Zhao Yue, Bai Yimin, Li Fumin, Zhang Ying, Chen Yu
Key Laboratory of Applied Surface and Colloid Chemistry Ministry of Education School of Chemistry and Chemical Engineering Shaanxi Normal University Xi'an 710062 P. R. China.
Key Laboratory of Macromolecular Science of Shaanxi Province Shaanxi Key Laboratory for Advanced Energy Devices School of Materials Science and Engineering Shaanxi Normal University Xi'an 710062 P. R. China.
Adv Sci (Weinh). 2020 Mar 16;7(9):2000012. doi: 10.1002/advs.202000012. eCollection 2020 May.
The 2D conductive metal-organic frameworks (MOFs) are expected to be an ideal electrocatalyst due to their high utilization of metal atoms. Exploring a new conjugated ligand with extra active metallic center can further boost the structural advantages of conductive MOFs. In this work, hexaiminohexaazatrinaphthalene (HAHATN) is employed as a conjugated ligand to construct bimetallic sited conductive MOFs (M2(M1∙HAHATN)) with an extra M-N moiety. Density functional theory (DFT) calculations demonstrate that the 2D conjugated framework renders M2(M1∙HAHATN) a high electric conductivity with narrow bandgap (0.19 eV) for electron transfer and a favorable in-plane porous structure (2.7 nm) for mass transfer. Moreover, the metal atom at the extra M-N moiety has a higher unsaturation degree than that at M-N linkage, resulting in a stronger ability to donate electrons for enhancing electroactivity. These characteristics endow the new conductive MOFs with an enhanced electroactivity for hydrogen evolution reaction (HER) electrocatalysis. Among the series of M2(M1∙HAHATN) MOF, Ni(Ni∙HAHATN) nanosheets with the optimal structure exhibit a small overpotential of 115 mV at 10 mA cm, low Tafel slope of (45.6 mV dec), and promising electrocatalytic stability for HER. This work provides an effective strategy for designing conductive MOFs with a favorable structure for electrocatalysis.
二维导电金属有机框架材料（MOFs）因其金属原子的高利用率有望成为理想的电催化剂。探索具有额外活性金属中心的新型共轭配体能够进一步提升导电MOFs的结构优势。在这项工作中，六亚氨基六氮杂三萘（HAHATN）被用作共轭配体来构建具有额外M-N部分的双金属位点导电MOFs（M2(M1∙HAHATN)）。密度泛函理论（DFT）计算表明，二维共轭框架使M2(M1∙HAHATN)具有高电导率，其电子转移的带隙窄（0.19电子伏特），且具有有利于传质的面内多孔结构（2.7纳米）。此外，额外M-N部分的金属原子比M-N键处的金属原子具有更高的不饱和程度，从而具有更强的供电子能力以增强电活性。这些特性赋予了新型导电MOFs在析氢反应（HER）电催化中增强的电活性。在一系列M2(M1∙HAHATN) MOF中，具有最佳结构的Ni(Ni∙HAHATN)纳米片在10 mA cm时表现出115 mV的小过电位、低塔菲尔斜率（45.6 mV dec）以及对HER有良好的电催化稳定性。这项工作为设计具有有利于电催化结构的导电MOFs提供了一种有效策略。
