Low-temperature green synthesis of multivalent manganese oxide nanowires

Manganese oxide nanomaterials hold promise for sustainable nanotechnologies given their utility for a variety of applications, the Earth's abundance of manganese, and their low toxicity relative to other nanomaterials. However green scalable synthesis methods for such nanomaterials are needed. We report here a green room-temperature synthesis of polycrystalline Mn₃O₄ nanowires. In this procedure, aqueous Mn(II) is oxidized under circumneutral conditions by atmospheric oxygen in the presence of nanocrystalline iron oxide (α-Fe₂O₃), an inexpensive catalyst, and a classic biochemical Good's buffer, PIPES (piperazine-N,N^I-bis(2- ethanesulfonic acid). The synthesis method is novel due to its simplicity, minimal energy input and waste output, and potential scalability. The Mn ₃O₄ nanowires have been characterized with a suite of electron microscopy techniques.