Atomically dispersed Pt-N-4 sites as efficient and selective electrocatalysts for the chlorine evolution reaction

Chlorine evolution reaction (CER) is a critical anode reaction in chlor-alkali electrolysis. Although precious metal-based mixed metal oxides (MMOs) have been widely used as CER catalysts, they suffer from the concomitant generation of oxygen during the CER. Herein, we demonstrate that atomically dispersed Pt-N-4 sites doped on a carbon nanotube (Pt-1/CNT) can catalyse the CER with excellent activity and selectivity. The Pt-1/CNT catalyst shows superior CER activity to a Pt nanoparticle-based catalyst and a commercial Ru/Ir-based MMO catalyst. Notably, Pt-1/CNT exhibits near 100% CER selectivity even in acidic media, with low Cl- concentrations (0.1M), as well as in neutral media, whereas the MMO catalyst shows substantially lower CER selectivity. In situ electrochemical X-ray absorption spectroscopy reveals the direct adsorption of Cl- on Pt-N-4 sites during the CER. Density functional theory calculations suggest the PtN4C12 site as the most plausible active site structure for the CER

Physicochemical properties and electrochemical behavior of Ebonex/Pt-based materials

Physicochem. properties and electrochem. behavior of Ebonex/Pt-based electrodes obtained with the use of a combined electrochem. method by electrodeposition of a thin platinum layer on substoichiometric titanium oxides (Ebonex) followed by heat treatment are studied. Phase compn. is found to depend substantially on the temp. of the electrode treatment. At temps. above 230°, a titanium-dioxide-hollandite phase is formed and facilitates thermal diffusion of platinum deep into the substrate. A previously unknown titanium-oxygen phase (310°) that affects the electrochem. behavior of the electrodes is discovered. Ebonex/Pt-based materials are n-type semiconductors, the flat band potentials and the no. of charge carriers of which are detd. by the formation conditions