Molecule-assisted modulation of the high-valence Co3+ in 3D honeycomb-like CoxSy networks for high-performance solid-state asymmetric supercapacitors

Wang, Haiyan; Yang, Ying; Li, Qinghao; Li, Wen; Ning, Jiqiang; Zhong, Yijun; Zhang, Ziyang; Hu, Yong

doi:10.1007/s40843-020-1476-2

Cited by 62 publications

(28 citation statements)

References 52 publications

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“…From Nyquist plots (Figure 5f), the Fe-Co 2 P@ Fe-N-C catalyst has the smallest charge transfer resistance (R ct ) of 19.4 Ω among these M-Co 2 P@M-N-C catalysts, signifying a faster electron transfer during the electrocatalytic processes. [58] Correspondingly, Fe-Co 2 P@Fe-N-C has the lowest Tafel slope value of 82 mV dec −1 (Figure 5g) and the highest C dl value of 13.8 mF cm −2 (Figure 5h; Figure S28, Supporting Information), confirming the excellent ORR reaction kinetics and the highly accessible active specific surface.…”

Section: Electrochemical Her Oer and Orr Performancementioning

confidence: 74%

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co₂P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Tian

et al. 2021

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Developing cost‐efficient multifunctional electrocatalysts is highly critical for the integrated electrochemical energy‐conversion systems such as water electrolysis based on hydrogen/oxygen evolution reactions (HER/OER) and metal‐air batteries based on OER/oxygen reduction reactions (ORR). The core–shell structured materials with transition metal phosphide as the core and nitrogen‐doped carbon (NC) as the shell have been known as promising HER electrocatalysts. However, their oxygen‐related electrocatalytic activities still remain unsatisfactory, which severely limits their further applications. Herein an effective strategy to improve the core and shell performances of core–shell Co2P@NC electrocatalysts through secondary metal (e.g., Fe, Ni, Mo, Al, Mn) doping (termed M‐Co2P@M‐N‐C) is reported. The as‐synthesized M‐Co2P@M‐N‐C electrocatalysts show multifunctional HER/OER/ORR activities and good integrated capabilities for overall water splitting and Zn‐air batteries. Among the M‐Co2P@M‐N‐C catalysts, Fe‐Co2P@Fe‐N‐C electrocatalyst exhibits the best catalytic activities, which is closely related to the configuration of highly active species (Fe‐doping Co2P core and Fe‐N‐C shell) and their subtle synergy, and a stable carbon shell for outstanding durability. Combination of electrochemical‐based in situ Fourier transform infrared spectroscopy with extensive experimental investigation provides deep insights into the origin of the activity and the underlying electrocatalytic mechanisms at the molecular level.

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Section: Electrochemical Her Oer and Orr Performancementioning

confidence: 74%

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co₂P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Tian

et al. 2021

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“…For the calculation, the specific capacitance is plotted against the slow scan rate up to a value of 20 mV/s and performed a regression fit using Equation (3). The obtained value for k 1 and k 2 was used to determine the fractional contribution in terms of diffusion and capacitance from total specific capacitance [72], as given in Figure 5g. Figure 5g shows that the contribution to the current response at a fixed potential is more diffusive than capacitive and decreases with the Al content.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Performance of Aluminum Doped Ni1−xAlxCo2O4 Hierarchical Nanostructure: Experimental and Theoretical Study

et al. 2021

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For electrochemical supercapacitors, nickel cobaltite (NiCo2O4) has emerged as a new energy storage material. The electrocapacitive performance of metal oxides is significantly influenced by their morphology and electrical characteristics. The synthesis route can modulate the morphological structure, while their energy band gaps and defects can vary the electrical properties. In addition to modifying the energy band gap, doping can improve crystal stability and refine grain size, providing much-needed surface area for high specific capacitance. This study evaluates the electrochemical performance of aluminum-doped Ni1−xAlxCo2O4 (0 ≤ x ≤ 0.8) compounds. The Ni1−xAlxCo2O4 samples were synthesized through a hydrothermal method by varying the Al to Ni molar ratio. The physical, morphological, and electrochemical properties of Ni1−xAlxCo2O4 are observed to vary with Al3+ content. A morphological change from urchin-like spheres to nanoplate-like structures with a concomitant increase in the surface area, reaching up to 189 m2/g for x = 0.8, was observed with increasing Al3+ content in Ni1−xAlxCo2O4. The electrochemical performance of Ni1−xAlxCo2O4 as an electrode was assessed in a 3M KOH solution. The high specific capacitance of 512 F/g at a 2 mV/s scan rate, 268 F/g at a current density of 0.5 A/g, and energy density of 12.4 Wh/kg was observed for the x = 0.0 sample, which was reduced upon further Al3+ substitution. The as-synthesized Ni1−xAlxCo2O4 electrode exhibited a maximum energy density of 12.4 W h kg−1 with an outstanding high-power density of approximately 6316.6 W h kg−1 for x = 0.0 and an energy density of 8.7 W h kg−1 with an outstanding high-power density of approximately 6670.9 W h kg−1 for x = 0.6. The capacitance retention of 97% and 108.52% and the Coulombic efficiency of 100% and 99.24% were observed for x = 0.0 and x = 0.8, respectively. First-principles density functional theory (DFT) calculations show that the band-gap energy of Ni1−xAlxCo2O4 remained largely invariant with the Al3+ substitution for low Al3+ content. Although the capacitance performance is reduced upon Al3+ doping, overall, the Al3+ doped Ni1−xAlxCo2O4 displayed good energy, powder density, and retention performance. Thus, Al3+ could be a cost-effective alternative in replacing Ni with the performance trade off.

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“…The requirements of electrolytes for SCs can be summarized as follow: high ion conductivity is the key to minimize the internal resistance of SCs, especially during large current discharge; the electrochemical stability and chemical stability of the electrolyte must be high enough to sustain long working life; the operating temperature range should be wide to meet the varying temperature of the working environment; the size of ions in the electrolyte should match the pore size of the electrode material (for electrochemical double-layer capacitors); and the electrolyte should be environmentally friendly [26]. Moreover, according to the theoretical prediction of the energy storage in SCs determined by the formula of E = 1/2 CV 2 [27][28][29][30][31][32][33][34][35][36][37] (E is energy density, C is the capacitance, and V is the working voltage of the capacitor), the working voltage should be high to achieve high energy density.…”

Section: Introductionmentioning

confidence: 99%

New types of hybrid electrolytes for supercapacitors

Wang

Ning

et al. 2021

Journal of Energy Chemistry

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Molecule-assisted modulation of the high-valence Co3+ in 3D honeycomb-like CoxSy networks for high-performance solid-state asymmetric supercapacitors

Cited by 62 publications

References 52 publications

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co₂P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co₂P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Electrochemical Performance of Aluminum Doped Ni1−xAlxCo2O4 Hierarchical Nanostructure: Experimental and Theoretical Study

New types of hybrid electrolytes for supercapacitors

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Molecule-assisted modulation of the high-valence Co3+ in 3D honeycomb-like CoxSy networks for high-performance solid-state asymmetric supercapacitors

Cited by 62 publications

References 52 publications

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co2P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co2P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Electrochemical Performance of Aluminum Doped Ni1−xAlxCo2O4 Hierarchical Nanostructure: Experimental and Theoretical Study

New types of hybrid electrolytes for supercapacitors

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Product

Resources

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Activity Promotion of Core and Shell in Multifunctional Core–Shell Co₂P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries

Activity Promotion of Core and Shell in Multifunctional Core–Shell Co₂P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn‐Air Batteries