Liquor ammonia mediated V(v) insertion in thin Co₃O₄ sheets for improved pseudocapacitors with high energy density and high specific capacitance value

Abstract

Ultrathin 2D Co3O4 and Co3V2O8 nanosheets have been produced from our modified hydrothermal technique (MHT). Both the materials have been proved to be extraordinary electrode materials for pseudocapacitors. The neat nanosheets of Co3O4 and Co3V2O8 exhibit a record specific capacitance value of 1256 F g(-1) and 4194 F g(-1) at 1 A g(-1) current density, respectively.

Suitable Morphology Makes CoSn(OH)6 Nanostructure a Superior Electrochemical Pseudocapacitor

“…These results suggest that both the materials exhibit capacitive property which originates mostly from the pseuducapacitor (0.05 V to 0.4 V) but participation of electrical double layer is also there (from the CV curve -01 V to 0.05 V). 3,39 Two-electrode system: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Scheme 2: Schematic presentation of the mechanism of action of the HNS CoSn(OH) 6 //AC when it was used as the two-electrode system.…”

“…3,32,33 At first, during hydrothermal treatment, at high temperature and high autogenic pressure the dissolution and crystallization of the amorphous particles occurred very fast. After that NH 3 presumably passivated the surface of CoSn(OH) 6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 In oriented attachment, to optimize the crystallographic orientation at low surface energy, particles rotate by themselves and irreversible attachment occurs through atom by atom addition.…”

“…Specific capacitance in three-electrode system, C SP = it/m∆V ----------------- (2) Specific capacitance in two-electrode system, C SP (2 electrode cell) = 4×C SP ---------------- (3) Where, I denotes the constant cathodic current, t signifies the discharge time, m is the weight of the active mass and ∆V is the potential window. Coulombic efficiency, η = t D /t C × 100 ----------------(4) t D is the discharging time and t C is the charging time.…”

“…Here, ammonia simultaneously acts as a hydrolysing as well as a bridging agent. 3 In the reaction medium NH 3 NH 3 binds to the surface of the particle through hydrogen bonding. Oxygen presents in the air act as the oxidising agent and transform Sn(II) to Sn(IV).…”

“…The large peak at around 531.1 eV indicates the binding energy of the hydroxyl group with metal ion. Another two small peaks around ~ 529.2 eV and ~ 532.6 eV stand for the presence of oxide and structural water with the CoSn(OH)6 compound 3,36,37. The peak for oxide compound originates due to the presence of trace amount of Co 3 O 4 (The ratio of CoSn(OH)6 : Co 3 O 4 = 25:1).Specific surface area and pore size distribution of the materials are absolutely crucial for a material to behave as a charge storage electrode material.Figure S7ademonstrate the N 2 adsorption-desorption curve for HNS and CNS samples at 77K within the relative pressure of 0 to1 (P/P 0 ) region.…”