In situ X-ray diffraction investigation of the evolution of a nanocrystalline lithium-ion sieve from biogenic manganese oxide

• Four different Li ion sieves were tested to recover Li+ from aqueous solutions.
• Sorption capacity of Li on HMO-MTs was more than 1.98 times higher than others.
• Formation of LMO-MTs from BB-MTs was studied by in situ HT-XRD.
• Effect of structural properties in HMO-MTs on Li sorption was discussed.

Microbial catalysis, a primary pathway for the generation of Mn oxides in most natural environments, provides potential to fabricate new materials. A microtube-type lithium manganese oxide (LMO-MT) was synthesized through a solid-state transformation using Mn-oxidizing fungus, Paraconiothyrium sp. WL-2. Compared with abiotic precursors, the lithium-ion sieve microtube (HMO-MT) showed better performance for Li+ recovery. In order to clarify the formation process of LMO-MTs, in situ high-temperature X-ray diffraction was used to compare with three synthetic references. The effects of calcination temperature on crystal phase, composition, particle size and lattice parameters of the LMO-MTs were systematically discussed. It was found that the poorly crystalline structure of biogenic precursor as well as high content of organic matter facilitated the formation of highly crystalline LMO-MTs at low temperature. The unique structural properties of LMO-MTs, including high crystallinity and small lattice constant, are attributed to the high Li+ sorption capacity of HMO-MTs.