Metallic nanoaggregates deposited on nonconductive oxides powders as catalysts have shown good efficiency in electrocatalytic hydrogenation (ECH). In this process, the polarization of the metallic nanoaggregates is very important. This polarization can be improved when the electrode material is conductive. Thus, the goal of this work was to study the effect of the conduction of the supported material on the ECH process. Tin dioxide was chosen as oxide because it can be obtained in non-conductive or conductive form by doping with fluorine. Palladium supported catalysts powders were prepared by the sol-gel method. These electrocatalysts were characterized by XRD, SEM, TGA/DSC, FTIR and electrical conductivity. The effects of temperature and time of calcination were also investigated. Comparison of nonconductive and conductive catalysts for ECH of phenol shows that conductive F-doped SnO 2 increases the rate of electrohydrogenation.

The electrocatalytic hydrogenation (ECH) of phenol and cyclohexanone was performed on a conductive Pd/SnO2:F catalyst. The catalyst was obtained by the impregnation method. We studied the influence of the pH of the supporting electrolyte, the conditioning pH, and the quantity of the conditioning charge passed before hydrogenation. Fourier transform infrared spectroscopy analysis showed that the functionalization of the catalyst surface by the acetic acid electrolyte depends on the pH. A direct correlation was observed between the efficiency of the hydrogenation, the pH of the electrolyte, and the electrode conditioning charge. Phenol hydrogenation was favored in acidic media, whereas cyclohexanone hydrogenation needed an acidic medium for conditioning and a basic medium for hydrogenation. The ECH rate appeared to depend on the functionalization of the catalyst surface, the adsorption of the target organic molecule on the catalyst, and its structural modification with the pH.