Reductive deposition of aluminum at a water-free ionic liquid/oil interface

The oil/water interface has been used as a reaction field for interfacial metal deposition via electron transfer between metal ions and reducing agents across the interface. However, the metals that can be deposited at liquid/liquid interfaces are limited to noble metals whose standard redox potential is more positive than that of water. In the present study, we designed a water-free liquid/liquid interface between a hydrophilic ionic liquid (IL) and oil (O) and succeeded in reductively depositing Al, a base metal that has a significantly negative standard redox potential and that is not reduced at water-based liquid/liquid interfaces. The morphology of the deposited Al was investigated and the reaction mechanism was explained as a combination of electron transfer and ion transfer across the IL/O interface.