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 Mn<sub>3</sub>O<sub>4</sub> nanowires. In this procedure, aqueous Mn­(II) is oxidized under circumneutral conditions by atmospheric oxygen in the presence of nanocrystalline iron oxide (α-Fe<sub>2</sub>O<sub>3</sub>), an inexpensive catalyst, and a classic biochemical Good’s buffer, PIPES (piperazine-N,N<sup>I</sup>-bis­(2-ethanesulfonic acid). The synthesis method is novel due to its simplicity, minimal energy input and waste output, and potential scalability. The Mn<sub>3</sub>O<sub>4</sub> nanowires have been characterized with a suite of electron microscopy techniques.