Biogenic Hematite from Bacteria: Facile Synthesis of Secondary Nanoclusters for Lithium Storage Capacity

Abstract

Ferrihydrite, or iron(III) (oxyhydr)oxide (Fe(OH)(3)), a representative scavenger of environmentally relevant toxic elements, has been repurposed as a low-cost and scalable precursor of well-developed hematite (alpha-Fe2O3) secondary nanoclusters with a hierarchically structured morphology for lithium-ion anode materials. Here, we report that the bacteria Clostridium sp. C8, isolated from a methane-gas-producing consortium, can synthesize self-assembled secondary hematite nanoclusters (similar to 150 nm) composed of small nanoparticles (similar to 15 nm) through the molecular structural rearrangement of amorphous ferrihydrite under mild conditions. The biogenic hematite particles, wrapped with graphene oxide reduced in situ by the reducing bacteria Shewanella sp. HN-41 via one-pot synthesis, deliver an excellent reversible capacity of similar to 1000 mA h g(-1) after 100 cycles at a current density of 1 A g(-1). Furthermore, the heat-treated hematite/rGO exhibits a capacity of 820 mA h g(-1) at a high current density of 5 A g(-1) and a reversible capacity of up to 1635 mA h g(-1) at a current density of 100 mA g(-1). This study provides an easy, eco-efficient, and scalable microbiological synthetic route to produce hierarchical hematite/rGO secondary nanoclusters with potential as high-performance Li-ion anode materials.