Modulation of TEA and methanol gas sensing by ion-exchange based on a sacrificial template 3D diamond-shaped MOF

This paper introduces a facile and simple method to synthesize ZnO and modulate ZnO to change into CuO/ZnO for realizing gas sensitive performance transformation from triethylamine (TEA) to methanol (CH3OH) without altering the original morphology of ZnO. ZnO with diamond-shape was prepared simply by calcining a three-dimensional (3D) Metal Organic Framework (MOF) {[Zn-5(L)(2)(H2O)(5)]center dot 7(DMA)center dot 10(H2O)}(n) (HPU-15) as template. When HPU-15 was immersed in solutions containing Cu(II) cations, Zn2+ in HPU-15 could be exchanged by Cu2+ rapidly. Then, CuO/ZnO was derived from the ion-exchanged product Cu@HPU-15. Unlike ZnO shows the selective responses to TEA, CuO/ZnO shows the highest sensing performance to CH3OH. First principles calculations showed that the gas sensitive performance transformation is mainly attributed to the changes of adsorption energy of materials, which gives rise to the transformation of sensing performance. Besides, the unique p-n junction is also beneficial for CH3OH gas sensing performance. Therefore, such post-synthetic metal ion exchange approach provides a novel strategy for the development of functional sacrificial template MOF materials for the application in the modulation of the sensitive performance of sensor.