Electrocatalytic reduction of aldehydes and ketones on nickel(II) tetraazamacrocyclic complex-modified graphite felt electrode

Electrocatalytic reduction of aldehydes and ketones was studied using a nickel(II) tetraazamacrocyclic complex-modified graphite felt (GF) electrode. The nickel(II) tetraazamacrocyclic complex-modified GF electrode was prepared by attaching nickel(II) (6-(2′-hydroxyethyl)-1,4,8,11-tetraazacyclotetradecane)perchlorate chemically to the carboxyl groups of a thin poly(acrylic acid) (PAA) layer coated on the GF. The modified electrode gave a reversible electron transfer for the nickel(II)–nickel(I) redox couple in cyclic voltammetry at −0.95 V versus Ag/AgCl. A preparative electrocatalytic reduction of aldehydes and ketones to the corresponding alcohol and pinacol compounds was successfully achieved on the modified electrode with an adequate current efficiency (46.9–75.9%), conversion (48.1–84.6%) and turnover number of the nickel catalyst (1053–2267).