Influences of the temperature on the porous α-Fe2O3 nanoarchitectures

are summarized in Table 1. As listed, the selected nanoarchitectures 1, 2, 3, and 4 corresponded with those obtained at 120°C (Figure 2d), 150°C (Figure 2e,f), 180°C (Figure 2g), and 210°C (Figure 2h) for 12.0 h, respectively. All N2 adsorption-desorption isotherms of the nanoarchitectures exhibited type IV with an H3-type hysteresis loop. The compact pod-like nanoarchitecture 1 (Figure 2d, D 104 = 23.3 nm) had a relatively large adsorbance of N2 (Figure 3a 1) learn more with a broad hysteresis loop at a relative pressure P/P 0 of 0.45 to 0.95 and a very narrow pore diameter distribution concentrating on 3.8 nm (Figure 3a 2). In contrast, the relative loose pod-like nanoarchitecture 2 (Figure 2e,f, D 104 = 27.3 nm) showed a relatively small adsorbance of N2 Selleck ACY-1215 (Figure 3b 1) with a typical H3-type hysteresis loop at a relative pressure P/P 0 of 0.45 to 1.0 and a bimodal pore diameter distribution concentrating on 3.8 and 17.5 nm (Figure 3b 2). The characteristic N2 adsorption-desorption isotherms (Figure 3a 1,b1) and pore size distributions (Figure 3a 2,b2) revealed that both nanoarchitectures 1 and 2 are of mesoporous structures. Figure 3 Nitrogen adsorption-desorption isotherms (a 1 -d 1 ) and corresponding

pore diameter distributions (a 2 -d 2 ) of the mesoporous α-Fe 2 O 3 . The nanoarchitectures were synthesized at different temperatures for 12.0 h, with the molar ratio of FeCl3/H3BO3/NaOH = 2:3:4. Temperature (°C) = 120 (a1, a2); 150 (b1, b2); 180 (c1, c2); 210 (d1, d2). The blue line with blue circles represents the desorption curve; the red line with square rectangles represents the all adsorption curve. Table 1 Mesoporous structures of the α-Fe 2 O 3 synthesized at different temperatures for 12.0 h (FeCl 3 /H 3 BO 3 /NaOH = 2:3:4) α-Fe2O3 nanoarchitecture Temperature Multipoint BET Total pore volume Average pore diameter   (°C) (m2 g−1) (cm3 g−1) (nm) 1 120 21.3 3.9 × 10−2 7.3 2 150 5.2 2.9 × 10−2 22.1

3 180 2.6 2.9 × 10−2 44.7 4 210 2.0 2.1 × 10−2 40.3 Comparatively, the looser pod-like nanoarchitecture 3 (Figure 2g, D 104 = 28.0 nm) demonstrated a similar adsorbance of N2 (Figure 3c 1) whereas with a narrow hysteresis loop at a relative pressure P/P 0 of 0.40 to 0.95 and a quasi-bimodal pore diameter distribution (Figure 3c 2). Very similarly, the loosest pod-like nanoarchitecture 4 (Figure 2h, D 104 = 31.3 nm) exhibited a relatively low adsorbance of N2 (Figure 3d 1) with also a narrow hysteresis loop at a relative pressure P/P 0 of 0.25 to 0.95 as well as a quasi-bimodal pore diameter distribution (Figure 3d 2). It was worth noting that the broad hysteresis loop (Figure 3a 1) and relative narrow one (Figure 3b 1) were due to the strong and weak capillarity phenomena existing within the compact (Figure 2d) and relatively loose nanoarchitectures (Figure 2e), respectively.