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Metal Ion Sensing and Electrochemical Behavior of MOF Derived ZnCo 2 O 4
Author(s) -
Ghosh Debamalya,
Pal Ananya,
Ghosh Susanta,
Gayen Arup,
Seikh Md. Motin,
Mahata Partha
Publication year - 2019
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201900439
Subject(s) - powder diffraction , chemistry , metal , electrochemistry , crystallography , ion , metal ions in aqueous solution , aqueous solution , analytical chemistry (journal) , inorganic chemistry , electrode , organic chemistry
A metal‐organic framework (MOF) with the formula {(H 2 pip)[Zn 1/3 Co 2/3 (pydc‐2,5) 2 (H 2 O)] · 2H 2 O}{where H 2 pip = piperazinediium, pydc‐2,5 = pyridine‐2,5‐dicarboxylate}, 1 , has been synthesized. To confirm the structure and phase purity of 1 , the PXRD pattern of the synthesized compound has been compared with the simulated PXRD pattern generated from the single‐crystal X‐ray data of isomorphous pure Co compound synthesized by Niu and Co‐workers. Upon solid state annealing of the mixed‐metal precursor (MOF) at 400 °C for one hour, pure ZnCo 2 O 4 was obtained. The phase purity of ZnCo 2 O 4 was confirmed by powder X‐ray diffraction. The as obtained ZnCo 2 O 4 was fully characterized using PXRD, SEM, TEM, and EDX elemental mapping analysis. The particle size is in the range of 22 nm‐40 nm with a dominant size of 30 nm. The emissive properties of nano‐sized ZnCo 2 O 4 at 391 nm upon excitation at 310 nm have been probed for the luminescence‐based sensing of metal cations in aqueous medium. The metal ion sensing is based on the differential change in intensity, which in turn reflects the strength of the interaction between ZnCo 2 O 4 and the metal ion. Such interactions can be rationalized within the framework of the ligand exchange rate as well as ionic radii of the aquated metal ions. Accordingly, Cu 2+ and Hg 2+ with highest ligand exchange rate exhibit maximum luminescence quenching, 71.7 % and 51 %, respectively. On the other hand, the nanostructured ZnCo 2 O 4 also shows super capacitance behavior with a maximum energy density of 2.39 Wh kg –1 at a power density of 36.66 W kg –1 .