Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
ACS Sens. 2021 Feb 26;6(2):429-438. doi: 10.1021/acssensors.0c01933. Epub 2021 Jan 11.
The structural diversity and tunability of metal organic frameworks (MOFs) represent an ideal material platform for a variety of practical scenarios ranging from gas storage/separation to catalysis, yet their application in chemiresistive gas sensing is relatively lacking, due to the requirements of combined electrical conductivity and optimized gas adsorption properties. Here, we report an effective chemical sensing strategy based on missing-linker two-dimensional conductive MOF, with incorporated defects via a simple ligand oxidization method. The multiple hydroxyl defect sites in the conductive 2D missing-linker amorphous Ni-HAB (aNi-HAB) enable rapid adsorption and desorption of water molecules compared to crystalline Ni-HAB (cNi-HAB). As a result, the aNi-HAB sensory device shows good sensitivity, selectivity, linearity, fast response/recovery rate, and excellent stability, which can be further improved by Nafion functionalization. Theoretical investigations including transient current measurement, density functional theory (DFT) calculations, and systematic performance evaluation of isostructural 2D aM-HAB (M = Cu, Fe, Co) MOF showed that unique transport mechanism and adsorption/activation energies originated from hydrogen bonding at defective sites are critical for enhanced humidity response, and further confirmed that defect engineering through missing linker incorporation is a general and effective approach to tune the sensing properties of conductive MOF materials.
金属有机骨架（MOFs）的结构多样性和可调变性为各种实际应用提供了理想的材料平台，包括气体存储/分离到催化等领域，然而，由于需要结合电导率和优化的气体吸附性能，它们在化学电阻式气体传感中的应用相对较少。在这里，我们报道了一种基于缺失配体二维导电 MOF 的有效化学传感策略，通过简单的配体氧化方法引入了缺陷。与结晶 Ni-HAB（cNi-HAB）相比，导电二维缺失链接无定形 Ni-HAB（aNi-HAB）中的多个羟基缺陷位可实现水分子的快速吸附和解吸。因此，aNi-HAB 传感器件表现出良好的灵敏度、选择性、线性度、快速的响应/恢复速率和出色的稳定性，通过 Nafion 功能化可进一步提高性能。包括瞬态电流测量、密度泛函理论（DFT）计算和同构二维 aM-HAB（M = Cu、Fe、Co）MOF 系统性能评估在内的理论研究表明，源于缺陷部位氢键的独特传输机制和吸附/活化能对于增强湿度响应至关重要，并进一步证实，通过缺失配体结合进行缺陷工程是调节导电 MOF 材料传感性能的一种通用且有效的方法。
