MnO2 nanospheres integrated into hierarchical porous carbon as electrode for high performance asymmetrical supercapacitors

MnO2 Nanoparticle‐Loaded Self‐Doped (N/O) Porous Carbon Derived from Orychophragmus Violaceus for Application as a High‐Performance Supercapacitor

“…Then, the spectra of C 1s, N 1s, O 1s and Mn 2p were further amplified and deconvolved to understand the functional groups on the surface. First, the high‐resolution Mn 2p spectra of OPC@MnO 2 32 (Figure 4b) contains two distinct peaks at 641.30 eV and 653.10 eV, corresponding to the two spin orbits of Mn 2p 3/2 and Mn 2p 1/2 , while an energy band difference of 11.80 eV is found between the two spin orbits, which matched the +4 valence of Mn in the MnO 2 structure [8,17] . Figure 4c and d show high‐resolution C 1s spectra of OPC and OPC@MnO 2 32.…”

“…The CV curves of OPC and OPC@MnO 2 x at a scanning rate of 5 mV s −1 over the potential window of −1.1 to −0.1 V as shown in Figure 7a. For OPC@MnO 2 x, these curves show a unique pair of redox peaks around −0.5 V and −0.2 V, implying the coexistence of electrochemical double‐layer capacitance and pseudocapacitance [17] . Additionally, the curves closure area of the OPC@MnO 2 x are larger than OPC, which indicates that the OPC@MnO 2 x have great electrochemical performance, which is owing to pseudocapacitance of their Faraday redox reaction.…”

“…Subsequently, O 1s of OPC (Figure 4g) can also be deconvoluted into three peaks at 531.50 eV, 532.55 eV, and 533.90 eV, corresponding to C=O, C−OH and C−O−C bonds [32,33] . O 1s of OPC@MnO 2 32 (Figure 4h) also can be divided into three peaks: Mn−O−Mn (528.91 eV), Mn−O−H/C=O (530.71 eV) and C−OH (532.35 eV) [7,17] . This indicates the presence of O‐containing functional groups in abundance for both the materials.…”

“…The NÀ X content in the OPC@MnO 2 32 is lower than OPC, and there is no NÀ Q bond, which can lead to poor conductivity. [17] Subsequently, O 1s of OPC (Figure 4g) can also be deconvoluted into three peaks at 531.50 eV, 532.55 eV, and 533.90 eV, corresponding to C=O, CÀ OH and CÀ OÀ C bonds. [32,33] O 1s of OPC@MnO 2 32 (Figure 4h) also can be divided into three peaks: MnÀ OÀ Mn (528.91 eV), MnÀ OÀ H/C=O (530.71 eV) and CÀ OH (532.35 eV).…”

“…As can be seen from Figure 5a, OPC is type I isotherm, and at relatively low pressure (P/P 0 < 0.2), the sample has a certain N 2 adsorption, indicating that the sample has a microporous structure. [17] OPC@MnO 2 x materials all exhibit type IV isotherms, in which the H1 hysteresis loop appears at relative pressure (P/P 0 = 0.6~0.9), demonstrating that they have abundant mesopores as well as a small number of micropores, [2] which may be due to the attachment of MnO 2 nanoparticles to some micropores of OPC. Finally, at high pressure, the N 2 adsorption capacity of all samples increased slightly, indicating the presence of large pores in them.…”