Electrochemical studies of the nickel catecholate complexes for detection of sulphur dioxide gas

摘要

Nickel catecholate complexes, bis(diphenylphosphino)ethanenickelcatecholate [(dppe)NiO_2C_6H_34-R_1] R_1 = CH_3 (1), C(CH_3)_3 (2), H (3) and F (4)] were studied using CV and SWV techniques between -1.5 and +1.5 V at 50mVs~(-1) in cathodic and anodic sweeps. Glassy carbon electrode was used with 0.1 M tetrabutylammonium tetrafluroborate (TBATFB) in CH_2Cl_2. Complexes 1-4 before addition of SO_2, showed approximately reversible behaviour (i_(pa)/i_(pc) ≈ 1 and ΔE ≈ 77-88 mV); oxidation peaks observed between +313 and +524mV, reduction peaks between +225 and +436mV, depending on the substituent on the ligand. Detection limit 0.01 ppm, linear range 0.01-20 ppm, sensitivity 0.02 ppm/mV (with SWV) were obtained. The complexes 1 and 2 could be used as voltammetric sensors while complexes 3 and 4 would be suitable as amperometric sensors, for monitoring industrial SO_2 emissions.