Boosting the charge transfer efficiency of metal oxides/carbon nanotubes composites through interfaces control

Single-Step Preparation of Ultrasmall Iron Oxide-Embedded Carbon Nanotubes on Carbon Cloth with Excellent Superhydrophilicity and Enhanced Supercapacitor Performance

“…Moreover, the corresponding CV curves at a scan rate of 100 mv s –1 (Figure c) also maintain a similar shape within the potential range of 2.0 V. The GCD curves of the ASC under the potential range of 0–2.0 V (Figure d) show a nearly triangular shape at various current densities form 0.5 to 40 mA cm –2 . The Ragone plot of the ASC based on the GCD data displays a high areal energy density of 0.11 mWh cm –2 at a power density of 0.5 mW cm –2 , which is higher than those of the previously reported ASCs, such as Fe 2 O 3 @b-C//Co­(OH) 2 (0.049 mWh cm –2 , 17.3 mW cm –2 ), Fe 2 O 3 NTs@PPy//MnO 2 (0.059 mWh cm –2 , 1 mW cm –2 ), NiO@N–C//Fe 2 O 3 @N–C (0.032 mWh cm –2 , 0.8 mW cm –2 ), and PPy@Fe 2 O 3 @SSY (0.039 mWh cm –2 , 1.3 mW cm –2 )…”

“…The rich O content would favor the wettability of electrode and provide more faradaic active sites in aqueous electrolyte. The O 1s XPS spectrum of FeO–CNT-20 (Figure h) shows two obvious peaks, which can be deconvoluted into four peak components with binding energies (BEs) at 530.0, 531.4, 532.4, and 533.7 eV, corresponding to the O 2– , OC–OH, C O, and C–OH, respectively. , Notably, the O 2– of Fe 2 O 3 has a large proportion of 42%, which is much higher than the previous reported Fe 2 O 3 /CNTs that were directly obtained under the inert atmosphere. , The intermittent dipping-burning approach gives an abundant iron resource and oxygen modification on the surface, being different from the conventional tip- or base-growth mode by CVD technologies. The C 1s spectrum shows four deconvoluted peaks with BEs at 284.8, 286.1, 287.5, and 288.8 eV, attributable to the C–C/C–Fe, C–O, CO, and OC–O, respectively. , The Fe 2p XPS spectrum (Figure j) exhibits the Fe electronic configuration in Fe 2p 3/2 at 711.2 eV and Fe 2p 1/2 at 724.8 eV with 13.6 eV peak separation accompanying with two shakeup satellites. , …”

“…The generation of disordered and defective CNTs is due to the relatively low combustion 32,41 Notably, the O 2− of Fe 2 O 3 has a large proportion of 42%, which is much higher than the previous reported Fe 2 O 3 /CNTs that were directly obtained under the inert atmosphere. 24,42 The intermittent dipping-burning approach gives an abundant iron resource and 43,44 The Fe 2p XPS spectrum (Figure 1j) exhibits the Fe electronic configuration in Fe 2p 3/2 at 711.2 eV and Fe 2p 1/2 at 724.8 eV with 13.6 eV peak separation accompanying with two shakeup satellites. 45,46 Figure 2a, b shows that the CC fiber is uniformly covered by Fe 2 O 3 /CNT structures.…”

“…Growing carbon nanotubes (CNTs) with metal oxide decoration on the current collector could realize an additive-free, self-supporting, and flexible electrode. − Thanks to the boosted ion diffusion kinetic and surface pseudocapacitance, Fe 2 O 3 /CNTs composites have been demonstrated to present a superior electrochemical performance . However, these inevitable time-consuming and costly technologies with complicated procedures such as acid-pretreatment, hydrothermal, magnetron sputtering, and atomic layer deposition limit their large-scale production. , Chemical vapor deposition (CVD) was generally employed to synthesize CNTs directly by using the metal catalyst (Fe, Co, and Ni) under the conditions of gaseous hydrocarbon and high temperature. ,− The carbon species would dissolve in the metal catalyst, and then the resulting atoms began to nucleate carbon nanotubes . However, the tip- or base-growth mechanism leads to only a small amount of metal oxides being dispersed on both ends of the CNTs .…”

Polypyrrole-Coated Low-Crystallinity Iron Oxide Grown on Carbon Cloth Enabling Enhanced Electrochemical Supercapacitor Performance

“…The construction of an Fe 2 O 3 /PPy interface could confine the Na + and limit diffusion in the bulk phase, thus providing more surface Faradaic reactions for charge storage. Table S1 lists the detailed comparisons of Fe 2 O 3 -based and D-Fe 2 O 3 @PPy/CC anodes for supercapacitors [ 18 , 19 , 33 , 34 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. The results further indicate the outstanding electrochemical performance of this D-Fe 2 O 3 @PPy/CC electrode.…”