Electrocatalytic activity of BasoliteTM F300 metal-organic-framework structures

For the case of the commercially available metal-organic framework (MOF) structure BasoliteTM F300 or Fe(BTC) with BTC = benzene-1,3,5-tricarboxylate, it is shown that the Fe(III/II) electrochemistry is dominated by reductive dissolution rather than ion insertion (which in marked contrast is dominating the behaviour of Fe(III/II) open framework processes in Prussian blues). Solid Fe(BTC) immobilised onto graphite or platinum working electrodes is investigated and it is shown that well-defined and reversible Fe(III/II) reduction responses occur only on platinum and in the presence of aqueous acid. The process is shown to follow a CE-type mechanism involving liberation of Fe(III) in acidic media, in particular for high concentrations of acid. Effective electrocatalysis for the oxidation of hydroxide to O2 (anodic water splitting) is observed in alkaline aqueous media after initial cycling of the potential into the reduction potential zone. A mechanism based on a MOF-surface confined hydrous iron oxide film is proposed.