Electrocatalytic reduction of nitrocompounds on gold UPD modified electrodes: Part 1. Reduction of nitrobenzene and 3-nitro-1,2,4-triazole on Au and Au/M(UPD) (M = Pb, Tl)

摘要: Abstract The underpotential deposition (UPD) of Pb and Tl has been found to exhibit a marked influence on the performance Au electrode for electroreduction nitro groups. In acid solutions, UPD shifts four-electron reduction wave nitrobenzene phenylhydroxylamine towards more negative potentials also causes complete inhibition step aniline. However, Pb(UPD) Tl(UPD) adatom layers catalyse 3-nitro-1,2,4-triazole in solutions. catalytic effect is characterized by positive shift attainment diffusion-controlled limiting currents at medium degrees coverages. At coverages, activity decreases current becomes kinetically controlled as bare Au. kinetic character was attributed dehydration reaction dihydroxylamine intermediate an ECCE sequence. observed coverages interpreted terms strong adsorption group with bridged complex involving substrate (Au) adsorbate atom (Pb,Tl) which favour NO bond cleavage. Finally, alkaline solutions it that monolayers 3-nitro-1,2,4-triazole.