Modified Electrode Of Rhodium (Ⅲ) Chloro Complex Of 1, 2-Naphthoquinone-1-oxime

1,2-naphthoquinone-mono-oximes (nqo) are good bidentate ligands to transition metals. The complexes of nqo, similar to 2,2'-bipyridine complexes which are excellent electrocatalysts, exhibited various electron-transfer behaviors. Glass carbon (GC) electrode was modified by rhodium cholor complex of 1,2-naphthoquinone-1-oximes (1-nqo) [Rh(vpy)2(1-nqo)Cl2] (vpy=4-vinylpyridine; 1-nqo=1,2-Naphthoquinone-1-Oxime). Electrocativities and electrocatalytic properties of the modified electrode were investigated in this thesis.On the cyclic voltammogram of the modified electrode C/[Rh(vpy)2(1-nqo)Cl2] in aqueous solution of 0.1 mol·dm-3 NaAc, peaks of reduction of Rh(Ⅲ) and reoxidation of the produced Rh(Ⅰ) complex on the electrode appeared at -0.45 and 0.34 V (vs. SCE), respectively. While the redox pair related to 1-nqo ligand appeared at -1.30 V. Upon successive cyclic voltammetric scans, a new redox pair appeared at -0.56 V due to the production of rhodium hydride complex.The modified electrode C/[Rh(vpy)2(1-nqo)Cl2] showed good electrocatalytic properties for electrochemical reduction of formic acid, oxalic acid and cyclohexanone in 0.1 mol·dm-3 NaAc. The reductive currents on the modified electrode were linearly with concerntrations of formic acid and oxalic acid in the range of 2.67～141.7 mmol·dm-3 and 2.0～20.00 mmol·dm-3, respectively. Reduction of formic acid, oxalic acid and cyclohexanone were performed at -0.9 V on the modified electrode. Formaldehyde and cyclohexanol were produced by electrochemical reduction of formic acid and cyclohexanone, based on gas chromatography (GC) analyses. The reduction product of oxalic acid is postulated glyoxylic acid.