The powder samples synthesized by the potassium citrate-assisted co-precipitation method are denoted as KFeRT and KFe60 to indicate the precipitation at room temperature and 60°C, respectively. Based on the results of MP-AES (Table ), elemental analysis (Table ), and TGA (Figure ), the compositions of KFeRT and KFe60 are estimated to be K1.49Fe[Fe(CN)6]0. and), confirming that the estimated compositions and refined structures were reasonably consistent. The lattice KFeFe-PBAs. We use the structural models of [Fe(CN)6] 4-vacancy-containing (KFeVC, inset in Figure ) and vacancy-free (KFeVF, inset in Figure ) to represent KFeRT and KFe60, respectively, in order to facilitate our discussion. Both samples showed a weak preedge peak at 7115.6 eV in the Fe K-edge X-ray absorption near-edge spectra (XANES, Figure ), demonstrating the typical octahedrally coordinated environment of the Fe centers. The main absorption peaks are observed at 7131.5 eV for KFeRT and 7130.9 eV for KFe60, being between the peaks of Prussian White (PW) and Berlin Green (BG) references (Figure ). In addition, the FT-IR spectra of the samples (Figure ) show the characteristic vibration modes of υ(CN), υ(FeC), and δ(FeCN), which are commonly observed from hexacyanoferrates. As shown in the SEM images (Figures and), both samples consisted of small nanoparticles and exhibited a certain level of agglomeration. The size of primary particles is in ranges of 30-50 nm (Figure ) and 50-80 nm (Figure ) for KFeRT and KFe60, respectively.