This was in accordance with the SEM observation (Figure 1c) and literature results [45, 46]. The thin hysteresis loops (Figure 3c 1,d1) were due to the slight capillarity phenomenon existing within the very loose nanoarchitectures (Figure 2g,h). As shown in Table 1, with the temperature increasing from 120°C to 150°C, to 180°C, and to 210°C, the corresponding

multipoint BET specific surface area of the nanoarchitecture decreased from 21.3 to 5.2, to 2.6, and to 2.0 m2·g−1, respectively. Meanwhile, the total pore volume changed from 3.9 × 10−2 to 2.9 × 10−2, to 2.9 × 10−2, and to 2.1 × 10−2 cm3·g−1, with a roughly decreasing tendency; the average pore diameter changed from 7.3 to 22.1, to 44.7, and to 40.3 nm, with a roughly increasing tendency. Thus, according to the general recognition of the porous materials [50], nanoarchitectures 3 and 4 selleck compound were determined as the mesoporous structures, whereas the pore diameters were near the macropores category. As a matter of fact, with the temperature increasing from 120°C to 210°C, the evolution of the BET specific surface area, total pore volume, and average pore diameter of the various-morphology pod-like α-Fe2O3 nanoarchitectures agreed with the variation of the D 104 calculated by the Regorafenib order Debye-Scherrer

equation, also in accordance with the SEM observation (Figure 2d,e,f,g,h). Evolution of the hydrothermal products during hydrothermal process Since the compact pod-like nanoarchitecture obtained at 105°C for 12.0 h (Figure 2c) bridged 1D β-FeOOH nanostructures

and pod-like α-Fe2O3 nanoarchitectures, the composition and morphology of the products hydrothermally treated at 105°C for various times were monitored, as shown in Figure 4. All hydrothermal products obtained at 105°C for 1.0 to 12.0 h exhibited relatively poor Nec-1s order crystallinity (Figure 4a 1,a2,a3). When treated for 1.0 h, the product was composed of β-FeOOH (JCPDS No. 34–1266) and detectable trace amount of maghemite (γ-Fe2O3, JCPDS No. 25–1402) in a nearly amorphous state (Figure 4a 1,b). With the time extending to 3.0 h, the product was only β-FeOOH with improved crystallinity, and γ-Fe2O3 no longer existed (Figure 4a 2,c). Notably, β-FeOOH at that period exhibited very tiny primary 1D morphology (i.e., fibrils, Erythromycin Figure 4c 1), and a rudimental pod-like aggregate was also observed (denoted as yellow dotted elliptical region in Figure 4c). When treated for 6.0 h, the hydrothermal products containing trace amount of β-FeOOH and majority of newly formed α-Fe2O3 (Figure 4a 3 were acquired, exhibiting pod-like or ellipsoidal-shaped aggregates entangled with 1D nanostructures (Figure 4d). The enlarged image (Figure 4e) corresponding to the red dot-dashed rectangular region in Figure 4d clearly showed that the selected developing pod-like aggregate was assembled by 1D β-FeOOH nanowhiskers.