Research on Three-Dimensional Porous Composite Nano-Assembled α-MnO[sub.2]/Reduced Graphene Oxides and Their Super-Capacitive Performance

• Published in: Materials Vol. 15; no. 23
• Main Authors: Luo, Liming, Peng, Huiyun, Sun, Hongjuan, Peng, Tongjiang, Yuan, Mingliang
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.11.2022
• Subjects: Graphene; Graphite; Oxides; China
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15238406

A series of three-dimensional porous composite α-MnO[sub.2]/reduced graphene oxides (α-MnO[sub.2]/RGO) were prepared by nano-assembly in a hydrothermal environment at pH 9.0-13.0 using graphene oxide as the precursor, KMnO[sub.4] and MnCl[sub.2] as the manganese sources and F[sup.−] as the control agent of the α-MnO[sub.2] crystal form. The α-MnO[sub.2]/RGO composites prepared at different hydrothermal pH levels presented porous network structures but there were significant differences in these structures. The special pore structure promoted the migration of ions in the electrolyte in the electrode material, and the larger specific surface area promoted the contact between the electrode material and the electrolyte ions. The introduction of graphene solved the problem of poor conductivity of MnO[sub.2], facilitated the rapid transfer of electrons, and significantly improved the electrochemical performance of materials. When the pH was 12.0, the specific surface area of the 3D porous composite material αMGs-12.0 was 264 m[sup.2]·g[sup.−1], and it displayed the best super-capacitive performance; in Na[sub.2]SO[sub.4] solution with 1.0 mol·L[sup.−1] electrolyte, the specific capacitance was 504 F·g[sup.−1] when the current density was 0.5 A·g[sup.−1] and the specific capacitance retention rate after 5000 cycles was 88.27%, showing that the composite had excellent electrochemical performance.