Filling Vacancies in a Prussian Blue Analogue Using Mechanochemical Post-Synthetic Modification

Abstract

<p>Mechanochemical grinding of polycrystalline powders of the Prussian blue analogue (PBA) Mn[Co(CN)$_{\textbf6}$]$_{\textbf{2/3}}\boldsymbol\Box_{\textbf{1/3}}\cdot\boldmath x$H$_{\textbf 2}$O and K$_{\textbf 3}$Co(CN)$_{\textbf 6}$ consumes the latter and chemically modifies the former. A combination of inductively-coupled plasma and X-ray powder diffraction measurements suggests the hexacyanometallate vacancy fraction in this modified PBA is reduced by approximately one third under the specific conditions we explore. We infer the mechanochemically-driven incorporation of [Co(CN)$_{\textbf 6}$]$^{\textbf 3-}$ ions onto the initially-vacant sites, coupled with intercalation of charge-balancing K$^+$ ions within the PBA framework cavities. Our results offer a new methodology for the synthesis of low vacancy PBAs, unlocking novel, high capacity PBA battery materials.</p>

Exploration of glassy state in Prussian blue analogues

“…1) 1 . Variation of metal choices and their oxidation state allows alteration of the vacancies content via the hexacyanometallates withdrawal to compensate for the electroneutrality 2,3 . Prussian blue (PB, Fe III [Fe II (CN) 6 ] 3/4 •nH 2 O) itself contains a quarter of the isolated vacancy site 4 .…”

Post-synthetic modification of Prussian blue type nanoparticles: tailoring the chemical and physical properties

“…In this sense, the recent example of mechanochemical PSM in bulk PBA opens interesting perspectives since it would avoid solvent competition or chemical incompatibilities between the guest and the host frameworks. 267 Such methodology has to be fully implemented at the nanoscale. Furthermore, the possi- bility to provide multistep PSM in the internal porosity of bulk PB/PBA has been rarely exploited.…”