Enhanced electrochemical supercapacitance of binder-free nanoporous ternary metal oxides/metal electrode

Abstract

Free-standing nanoporous Ni-Cu-Mn mixed metal oxides on metal with a high surface area was fabricated by chemically dealloying a Ni8Cu12Mn80 single-phase precursor, followed by electrochemical oxidation in an alkaline solution. Electrochemical analysis shows that first Cu and Mn-based metal oxides formed by the electrochemical oxidation. Ni-based oxides grow later with the increase of electrochemical CV cycles and mix with the Cu/Mn oxides, forming a relatively stable mixed metal oxides thin film on metal ligament network. Due to the different electrochemical properties of each metal and the synergetic effect between them, the mixed ternary metal oxides formed on metal nano-ligament can operate stably between a wide potential window (1.5V) in 1.0M KOH aqueous solution when tested as a free-standing supercapacitor electrode. Due to the high volumetric surface area, wide operating potential window and excellent conductivity, the nanoporous metal oxides@metal composite exhibits a high volumetric capacitance (∼500Fcm(-3)), high energy density (∼38mWhcm(-3)) and good cycling stability.

Unraveling the Charge Storage and Activity‐Enhancing Mechanisms of Zn‐Doping Perovskite Fluorides and Engineering the Electrodes and Electrolytes for Wide‐Temperature Aqueous Supercabatteries

“…The above-indicated Fe, Bi, Cu, C and O elements of the FeBiCu@rGO sample can be further detected by the EDS tests (Figure S23c), and the SEM/TEM images in Figures S22a and S23a,b demonstrate the rough surface morphology and aggregated particles with the size range from nanosize to microlevel, which are owing to the aggregation of ultrafine nanoparticles; moreover, the particles FeBiCu and rGO have been tightly combined with each other via the ball-milling treatment, which is helpful to improve the performance of the FeBiCu@ rGO electrode. [6f ] The electrochemical reaction processes of the ternary FeBiCu@rGO electrode were evaluated with the help of mono Fe@rGO, Bi@rGO, and Cu@rGO electrodes, as shown in Figure 5b,c, the CV and GCD plots of the FeBiCu@ rGO electrode combine the characteristics of Fe@rGO, Bi@rGO and Cu@rGO, which shows the four pairs of redox couples and charging/discharging plateaus originating from the Fe 2 O 3 /Fe(OH) 2 (A1/C1), [18] Bi 2 O 3 /Bi 2 O 2 /Bi (A3/C3, A2/C2), [1k,19] and Cu(OH) 2 , CuO/Cu 2 O/Cu (A4/C4, A3"/C1"), [20] and the specific reaction progress can be seen in Equations. S19-S24, Supporting Information, moreover, the Fe/Bi redox species behave more actively than the Cu species in the FeBiCu@rGO electrode based on the redox areas and charging/discharging times.…”

Microstructural/Compositional Regulations and Actuation Properties of Nanoporous Ternary CuMnNi Alloys Fabricated by Electrochemical Dealloying

“…During the positive scanning, the oxidation peaks on the CV curves can be assigned as follows. The anodic peaks (A1 and A2) can be attributed to Mn(OH) 2 + OH − → MnOOH + H 2 O + e − and the formation of Cu (I), respectively [12c,16] . Note that Mn can be oxidized into Mn(OH) 2 at a very low potential (≈−1.8 vs SCE) in an alkaline solution, [16c] therefore, the Mn surface is already covered with Mn(OH) 2 before the positive potential is applied [12c] .…”

“…The anodic peaks (A1 and A2) can be attributed to Mn(OH) 2 + OH − → MnOOH + H 2 O + e − and the formation of Cu (I), respectively [12c,16] . Note that Mn can be oxidized into Mn(OH) 2 at a very low potential (≈−1.8 vs SCE) in an alkaline solution, [16c] therefore, the Mn surface is already covered with Mn(OH) 2 before the positive potential is applied [12c] . The oxidation of MnOOH into MnO 2 and Cu (II) formation occurs in the broad peak A3 [12c,16] .…”

“…Note that Mn can be oxidized into Mn(OH) 2 at a very low potential (≈−1.8 vs SCE) in an alkaline solution, [16c] therefore, the Mn surface is already covered with Mn(OH) 2 before the positive potential is applied [12c] . The oxidation of MnOOH into MnO 2 and Cu (II) formation occurs in the broad peak A3 [12c,16] . The redox peak (A4 and C3) is attributed to the redox reaction of β‐Ni(OH) 2 + OH − ↔β‐NiOOH + H 2 O + e − [12d] .…”

“…The redox peak (A4 and C3) is attributed to the redox reaction of β‐Ni(OH) 2 + OH − ↔β‐NiOOH + H 2 O + e − [12d] . During the negative scanning, the cathodic peaks (C1 and C2) are attributed to the reduction of Cu (II) into Cu (I) and MnO 2 into MnOOH, respectively [12c,16] . In addition, the hydrogen adsorption/desorption would occur in the potential range between −1.4 and −0.8 V versus SCE.…”