Oriented Catalytic Oxidation Induced Fabrication of CuO/Mn₃O₄ Hierarchical Arrays as Binder‐Free Electrodes for High‐Performance Supercapacitor

Abstract

sulfides, [11] and transition metal oxides (TMOs). [12][13][14][15] TMOs are usually considered to be a potentially ideal electrode material due to their rich valence states and diversified structure styles, enabling efficient Faradaic redox reactions and a high theoretical capacity. [16][17][18] Noteworthy, CuO as one kind of TMOs has been paid exceptional attention on the account of its rich reserves, unique physicochemical properties, non-toxic properties, and environmental stability. [19][20][21] When employed as electrode material for supercapacitors, CuO typically possesses an attractive theoretical capacity of 1800 F g −1 . [22] Unfortunately, single and pristine CuO always suffers from undesirable specific capacity and unsatisfactory cycling stability because of the poor intrinsic conductivity and deteriorating structural collapse during charging/discharging processes, which has critically hindered its application in supercapacitors. [23,24] To address the performance deficiencies of CuO electrode materials, various CuO-based hybrid materials with diversified hierarchical micro-/nano-structures have been explored as the effective alternatives for supercapacitors, which display superior electrochemical performance owing to the improved ionic and electronic transfer. [25,26] In particular, when designed to grow on conductive substrates, the CuO-based hybrid materials could be directly applied as binderfree electrodes for supercapacitors, and generally exhibit much enhanced electronic conductivity and structural stability. [27][28][29][30][31][32][33] Up to now, most of such CuO-based hybrids as binder-free electrodes are usually derived from the Cu(OH) 2 nanoarray templates, which are in-situ grown on Cu or Ni substrates, simply by thermal dehydration. Through subsequent chemical deposition or etching with transition metal salts under specific reaction conditions, the generated CuO nanorod arrays from the Cu(OH) 2 nanoarray templates would evolve into the target products with various hybrid components and rich nanostructures. For example, taking advantage of this strategy, Chen et al. have synthesized CuO@MnO 2 nanowire arrays on Cu grids by the combination of wet etching and hydrothermal deposition, the obtained hybrid electrode displays improved specific capacitance due to the synergistic interaction of each component. [27]

Emerging two-dimensional nanostructured manganese-based materials for electrochemical energy storage: recent advances, mechanisms, challenges, and prospects

“…10c and d. 181 Recently, in situ porous carbon-coated hexagonal Mn 3 O 4 (p-Mn 3 O 4 @C) nanosheets were applied for screen-printed planar SCs, which has attracted extensive attention. p-Mn 3 O 4 @C displayed superior specific capacitance (386 F g −1 at 1 A g −1 ) and exhibited an expanded voltage window of 0–1.3 V ( vs. Ag/AgCl).…”