Influence of Halide Ions on Electrochemical Reduction of Carbon dioxide over Copper Surface

The electrochemical reduction of carbon dioxide (ERCO2) to valuable chemicals and fuels is one of the promising approaches for reducing excess CO2 concentration. However, it faces the great challenge of...

Photoelectrocatalytic C–H halogenation over an oxygen vacancy-rich TiO2 photoanode

Photoelectrochemical cells are emerging as powerful tools for organic synthesis. However, they have rarely been explored for C–H halogenation to produce organic halides of industrial and medicinal importance. Here we report a photoelectrocatalytic strategy for C–H halogenation using an oxygen-vacancy-rich TiO2 photoanode with NaX (X=Cl−, Br−, I−). Under illumination, the photogenerated holes in TiO2 oxidize the halide ions to corresponding radicals or X2, which then react with the substrates to yield organic halides. The PEC C–H halogenation strategy exhibits broad substrate scope, including arenes, heteroarenes, nonpolar cycloalkanes, and aliphatic hydrocarbons. Experimental and theoretical data reveal that the oxygen vacancy on TiO2 facilitates the photo-induced carriers separation efficiency and more importantly, promotes halide ions adsorption with intermediary strength and hence increases the activity. Moreover, we designed a self-powered PEC system and directly utilised seawater as both the electrolyte and chloride ions source, attaining chlorocyclohexane productivity of 412 µmol h−1 coupled with H2 productivity of 9.2 mL h−1, thus achieving a promising way to use solar for upcycling halogen in ocean resource into valuable organic halides.

Induced Effect of Gold Nanoparticles (AuNPs) and Halide Ions on Pyridoxine Molecule Stability

The electrochemical behavior of pyridoxine was studied in 0.1 mol × L−1 NaX (X = F, Cl, Br) support electrolyte on a gold electrode using cyclic voltammetry and UV–Vis spectrophotometry. The influence of gold nanoparticles (AuNPs) on the electrochemical behavior of pyridoxine was studied. The experimental results obtained by both cyclic voltammetry and UV–Vis spectrophotometry indicate strong interactions in the B6 and NaBr/NaCl_AuNP systems, while in the NaF_B6_AuNP ternary system the results indicate a mechanism of direct electrochemical degradation of vitamin B6. The experimental results obtained for the electrochemical degradation of pyridoxine, in the presence of chloride and bromide ions, indicate strong interactions in the NaCl_B6_AuNP and NaBr_B6_AuNP systems associated with the spectrophotometric identification of the electrogenerated intermediates, while in the presence of fluoride ions no such products are identified. The development of the mechanism of electrochemical degradation of the pyridoxine molecule predicts both the formation of the corresponding electrogenerated intermediates and the steps of electro-incineration in a direct mechanism.