Missing-Linker 2D Conductive Metal Organic Frameworks for Rapid Gas Detection

Abstract

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.

Room-Temperature Semiconductor Gas Sensors: Challenges and Opportunities

“…Tailor-made molecular design is also attractive for the rational design of MOFs-based gas sensors. − Mirica et al utilized a heterobimetallic 2D conducting MOFs with metallophthalocyanine units interconnected via Cu nodes to achieve ultrahighly sensitive detection of ppm levels of carbon monoxide (CO) at RT. Figure k shows the SEM image of the CoPc-O 8 -Cu MOF.…”

Metal–organic framework based systems for CO2 sensing

“…Despite these promising results which reveal the potential of 2D MOFs in tuning and optimising chemiresistive responses, the synthesis of conductive 2D MOFs remains synthetically challenging and limited to conjugated benzene rings and porphyrin rings. 56 To circumvent the low conductivity of MOFs, composite materials have also been synthesised. 25,57 25 The sensor device includes a dried paste containing carbon black or single walled carbon nanotubes and polytetrafluoroethylene (PTFE) which are placed as a film on glass slides using silver conductive paint.…”

MOF-derived electrochemical catalyst Cu–N/C for the enhancement of amperometric oxygen detection

“…[34][35][36][37][38] The catalysts could be provided with more active sites, which would improve the electrical conductivity. [39][40][41][42][43] Apart from the fact that Fe and Co have been widely investigated as transition metal electrochemical catalysts, it was found that Cu-embedded catalysts possess higher catalysis performance with higher conductivity and enhanced charge transfer and hence can be considered as a promising candidate. [44][45][46][47] In addition, owing to the high surface area provided by the porous nanocarbon structure, Cu and N codoped carbon (Cu-N/C) catalysts are sought after due to their satisfactory catalysis performance.…”