Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation

Zequine, Camila; Wang, Fangzhou; Li, Xianglin; Guragain, Deepa; Mishra, Sanjibani; Siam, Khamis; Kahol, Pawan K.; Gupta, Ram K.

doi:10.3390/app9040793

Cited by 29 publications

(14 citation statements)

References 30 publications

(31 reference statements)

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“…Figure 9a shows the side view along the x-axis of the crystal structure of Ni 1−x Al x Co 2 O 4 , while Figure 9b shows the band-gap variation from 2.42 eV to 4.82 eV for the different values of x. For the system without Al atom, which is Ni 1 Co 2 O 4, the band gap was found at 2.42 eV, which agrees with the previously reported experimental values of 2.06 eV [86] cates lower charge transfer resistance [81]. These variations of the EIS curve from semicircle towards higher frequencies and linearity towards lower frequencies relate to reversible Faradaic redox reaction and access of OH − ions into the pore of the electrode material.…”

Section: Resultssupporting

confidence: 89%

“…The semicircle at the high-frequency range is due to the Faradaic charge transfer resistance (R ct ) of the redox reaction between the electrode and electrolyte. The decrease in the diameter of the semicircle indicates lower charge transfer resistance [81]. These variations of the EIS curve from semicircle towards higher frequencies and linearity towards lower frequencies relate to reversible Faradaic redox reaction and access of OH − ions into the pore of the electrode material.…”

Section: Resultsmentioning

confidence: 98%

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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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Section: Resultssupporting

confidence: 89%

Section: Resultsmentioning

confidence: 98%

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

et al. 2021

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“…Its catalytic mechanism will be presented in detail in later sections. In the meantime, a few other works also investigate the catalytic activities of Co‐, Mn‐, and Fe‐based catalysts in UOR as well . Based on the excellence of these transition metals, several material design and synthesis strategies are adopted to optimize their catalytic performance.…”

Section: Introductionmentioning

confidence: 99%

Designing Advanced Catalysts for Energy Conversion Based on Urea Oxidation Reaction

Zhu

Liang

Zou

2020

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Urea oxidation reaction (UOR) is the underlying reaction that determines the performance of modern urea‐based energy conversion technologies. These technologies include electrocatalytic and photoelectrochemical urea splitting for hydrogen production and direct urea fuel cells as power engines. They have demonstrated great potentials as alternatives to current water splitting and hydrogen fuel cell systems with more favorable operating conditions and cost effectiveness. At the moment, UOR performance is mainly limited by the 6‐electron transfer process. In this case, various material design and synthesis strategies have recently been reported to produce highly efficient UOR catalysts. The performance of these advanced catalysts is optimized by the modification of their structural and chemical properties, including porosity development, heterostructure construction, defect engineering, surface functionalization, and electronic structure modulation. Considering the rich progress in this field, the recent advances in the design and synthesis of UOR catalysts for urea electrolysis, photoelectrochemical urea splitting, and direct urea fuel cells are reviewed here. Particular attention is paid to those design concepts, which specifically target the characteristics of urea molecules. Moreover, challenges and prospects for the future development of urea‐based energy conversion technologies and corresponding catalysts are also discussed.

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“…After long-term exploration by researchers, numerous non-noble metal-based electrocatalysts have been reported in recent years, especially transition-metal-based catalysts, for example, transition-metal alloys, , oxides, , sulfides, , phosphides, , and so forth. Among these, transition-metal phosphides were widely concerned relying on their unique electronic structure and catalytic effect, regarded as a kind of promising non-noble metal catalysts. , Plentiful monometallic phosphides, such as FeP, CoP, and Ni 2 P, have been already investigated and used as catalysts in the electrochemical field, showing pretty good electrocatalytic performance.…”

Section: Introductionmentioning

confidence: 99%

3D Cross-Linked Structure of Manganese Nickel Phosphide Ultrathin Nanosheets: Electronic Structure Optimization for Efficient Bifunctional Electrocatalysts

Yang

Yuan

Wang

et al. 2021

ACS Appl. Energy Mater.

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As the important anodic reactions in electrochemical hydrogen production, both the oxygen evolution reaction (OER) and urea oxidation reaction (UOR) are proved to be the bottleneck needed to be resolved because of their sluggish 4e– or 6e– transfer process. High-efficiency and low-cost electrocatalysts are urgently in need to overcome these blocks. In this work, the manganese nickel phosphide nanosheets (Mn x Ni2–x P) with a three-dimensional (3D) cross-linked structure in situ grown on Ni foam are developed and serve as a bifunctional electrocatalyst toward OER and UOR. The experimental and theoretical methods are employed to get a comprehensive understanding of the catalytic behaviors of the obtained samples. Compared with the monometallic phosphide, Ni2P, and commercial RuO2, Mn x Ni2–x P exhibits superior performance with the lowest overpotential and impressive longevity. Mn x Ni2–x P requires a small overpotential of 196 mV and an ultralow potential of 1.24 V to obtain a current density of 10 mA cm–2 during the OER and UOR process, respectively. The theoretical consequences also confirm the benign electronic conductivity and efficient active sites for the OH– adsorption of Mn x Ni2–x P, reconfirming that Mn x Ni2–x P can serve as an effective bifunctional electrocatalyst for both OER and UOR.

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Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation

Cited by 29 publications

References 30 publications

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

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

Designing Advanced Catalysts for Energy Conversion Based on Urea Oxidation Reaction

3D Cross-Linked Structure of Manganese Nickel Phosphide Ultrathin Nanosheets: Electronic Structure Optimization for Efficient Bifunctional Electrocatalysts

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