Tetrathiafulvalene Shuttling Electrons between Copper-MOFs and Electrodes for Glucose Oxidation and Fuel Cells

We propose a new concept that electron transfer mediators could be employed to shuttle electrons between metal-organic frameworks (MOFs) and electrodes and thus can enhance MOFs' catalytic activities significantly. Here, we report that a classic electron transfer mediator, tetrathiafulvalene (TTF), which has been conventionally used as a part of organic conductive salts and for promoting electron transfer between redox biological enzymes and electrodes, could efficiently shuttle electrons between a model MOF material, Cu-BTC, and electrodes. Thereby, TTF dramatically boosted the electrocatalytic activity of Cu-BTC for glucose oxidation and the resulting biofuel cells consuming glucose. Different from the conventional and typical role of TTF as the electron transfer mediator for the biological enzymes in an electrochemical configuration, it is discovered that TTF can match this role for the nonbiological MOFs at electrodes as well. Since a large number of MOFs and electron transfer mediators are available, this work could open up a new approach for myriad applications, including catalysis, fuel cells, and energy conversion.