High and selective CO2 uptake, H2 storage and methanol sensing on the amine-decorated 12-connected MOF CAU-1

The amine-decorated microporous metal-organic framework CAU-1 was readily synthesized and activated using a home-made efficient protocol. It exhibited a high heat of adsorption for CO2, high CO2 uptake capacity, and an impressive selectivity for CO2 over N-2. At 273 K and up to 1 atm, CO2 uptake capacity can reach as much as 7.2 mmol g(-1). Comparatively, the CH4 and N-2 uptakes at 273 K and 1 atm were only 1.34 mmol g(-1) and 0.37 mmol g(-1), respectively. The CO2/N-2 selectivity was 101 : 1 at 273 K. The isosteric heat of adsorption (Q(st)) for CO2 was similar to 48 kJ mol(-1) at the onset of adsorption, and it decreases to similar to 28 kJ mol(-1) at higher CO2 pressures. Furthermore, CAU-1 can adsorb 2.0 wt% and 4.0 wt% hydrogen at 77 K under 1 atm and 30 atm, respectively. The adsorption characteristics of CAU-1 for methanol investigated in situ with a quartz crystal microbalance (QCM), indicated that this particular MOF structure can be used as a highly sensitive sensor for methanol detection such as direct methanol fuel cells.