Observation of morphology resembling Hydrangea macrophylla flower in SILAR-deposited MFe₂O₄ (M=Co²⁺, Ni²⁺, Mn²⁺) nanocrystallites: synergetic effect on electrochemical performance

Abstract

The successive ionic layer adsorption and reaction (SILAR) experimental process has been used to develop a high-efficiency electrode of MFe 2 O 4 (M = Ni, Co and Mn) on substrates at ambient temperature. Structural, morphological and electrochemical properties have been investigated using x-ray diffraction (XRD), a scanning electron microscope (SEM) and an electrochemical test station, respectively. A morphology resembling the Hydrangea macrophylla flower has been observed and tuned with varying Fe concentration. The formation of MFe 2 O 4 demonstrates the efficient electrochemical behavior and the specific capacitance has been evaluated as ~1380, ~972 and ~815 Fg −1 for CoFe 2 O 4 (CF), NiFe 2 O 4 (NF) and MnFe 2 O 4 (MF), respectively, at a current density of 1 Ag −1 . Also, the developed electrodes maintain excellent cyclic retention of ~92%, ~89% and ~86% for CF, NF, and MF, respectively, up to 5000 cycles. Further, asymmetric solid-state supercapacitor (ASC) devices have been fabricated using the best compositions of MFe 2 O 4 as a positive electrode and carbon black (CB) as a negative electrode, and successfully illuminate a 1.8 V commercial LED.

Two-dimensional layered nickel-based coordination polymer for supercapacitive performance

“…6 Substantial research has been carried out to develop alternative transition metals oxides/conducting polymer composites to achieve higher specific capacitance and energy density. 7,8 Moreover, electrolytic cations have a significant impact on the electrochemical performance. For pseudocapacitive materials, the rate capability and capacitance are highly affected by the charge storage mechanism occurring in the bulk or at the surface, and through the diffusion of intercalated/de-intercalated ions.…”

Synergistic enhancement of the near-infrared luminescence properties of Ni2+-doped SrTiO3 perovskite phosphors and their application

“…The signal at g = 2.35 can be attributed to O 3À vacancy radicals, and the signals at g = 2.186, 2.131 and 1.996 can be attributed to Ni 2+ ions, which suggests that the positional symmetry around Ni 2+ is mainly octahedral. 22,23 In contrast, the This journal is © The Royal Society of Chemistry 2023 signals of Ni 2+ in the SrTiO 3 -Ni 2+ -Yb 3+ -Ta 5+ sample doped with charge compensators was significantly stronger than that of SrTiO 3 -Ni 2+ , while the intensity of O À vacancy radicals decreased, which may be due to charge imbalance in SrTiO 3 -Ni 2+ making a portion of Ni 2+ become Ni 3+ , thus weakening the resonance signal. Therefore, the EPR test results support the mechanism of charge compensation as it increased the content of Ni 2+ luminescence centers and reduced the existence of electron vacancies.…”

Miniaturization of transition metal hydroxides to hydroxide dots: A direction to realize giant cyclic stability and electrochemical performance

“…In Figure S5A to E, discharge curves are depicted for different Co/Ni hydroxides dots. The CN 1:0, CN 0:1, CN 1:0.5, CN 1:1, and CN 1:2 delivered specific capacitance of 886, 799, 1334, 1926, and 1565 F g À1 , respectively, at 1 A g À1 (Figure 6A), and evaluated using this equation: 37,69,70…”