Synthesis of Silver Hollandite

The synthesis of silver hollandite, Ag_yMn₈O₁₆·nH₂O, was performed using an ambient pressure reflux reaction approach as previously described16 17 (link). Samples were heat treated at 300°C under air prior to microscopic analysis. X-ray powder diffraction patterns were collected on a Rigaku SmartLab and indexed to Ag_1.8Mn₈O₁₆ (JCPDS no. 87-087)38 . Crystallite sizes were determined by applying the Scherrer equation to the (211) peak after LaB₆ correction. Inductively coupled plasma-optical emission spectroscopy (Inductively coupled plasma-optical emission spectroscopy ) was employed on a ThermoScientific iCap 6,000. Thermogravimetric analysis (TGA) was collected on a TA Instruments SDT Q600, where water content was estimated based on weight loss to 360 °C (refs 7 , 15 ). On the basis of results of X-ray powder diffraction, ICP-OES and TGA, the composition was assigned as Ag_1.63Mn₈O_15.7·0.84H₂O. In addition, a series of chemically lithiated materials were prepared using LiBH₄ as a lithiating reagent and studied as reference samples for ex situ TEM.