Rich Surface Oxygen Vacancies of MnO<sub>2</sub> for Enhancing Electrocatalytic Oxygen Reduction and Oxygen Evolution Reactions

Zhuang, Qifeng; Ma, Na; Yin, Zhen‐Qiang; Yang, Xue; Zhang, Yin; Gao, Jian; Xü, Yao; Wang, Hong; Kang, Jianli; Xiao, Dequan; Li, Jianxin; Li, Xifei; Ma, Ding

doi:10.1002/aesr.202100030

Cited by 40 publications

(31 citation statements)

References 52 publications

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“…30 Out of all four phases of MnO 2 , the latter three were extensively studied for their wide variety of energy-related applications, whereas α-MnO 2 was studied for those applications only in a marginal way. 31 Although the various MnO 2 -based materials were extensively studied for OER, their catalytic activities are still not comparable with the state-of-the-art catalysts. In the same line, the OER activity of MnO 2 was too poor in 0.1 M KOH solution; for improvizing this activity, here for the very first ■ EXPERIMENTAL SECTION Synthesis of MnO 2 Nanoneedle and Ni-Doped MnO 2 Nanoneedle.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The different phases of MnO 2 materials used are described by the number of octahedral subunits ( n × m ); for example, α-MnO 2 consists of a 2 × 2 open tunnel, whereas β-MnO 2 consists of a 1 × 1 open tunnel formed by a single strand of edge-sharing MnO 6 octahedra, and so on for δ-MnO 2 and γ-MnO 2 . Out of all four phases of MnO 2 , the latter three were extensively studied for their wide variety of energy-related applications, whereas α-MnO 2 was studied for those applications only in a marginal way . Although the various MnO 2 -based materials were extensively studied for OER, their catalytic activities are still not comparable with the state-of-the-art catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of the OER Kinetics of the Less-Explored α-MnO₂ via Nickel Doping Approaches in Alkaline Medium

et al. 2021

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Development of a low-cost transition metal-based catalyst for water splitting is of prime importance for generating green hydrogen on an industrial scale. Recently, various transition metal-based oxides, hydroxides, sulfides, and other chalcogenidebased materials have been synthesized for developing a suitable anode material for the oxygen evolution reaction (OER). Among the various transition metal-based catalysts, their oxides have received much consideration for OER, especially in lower pH condition, and MnO 2 is one of the oxides that have widely been used for the same. The large variation in the structural disorder of MnO 2 and internal resistance at the electrode−electrolyte interfaces have limited its large-scale application. By considering the above limitations of MnO 2 , here in this work, we have designed Ni-doped MnO 2 via a simple wet-chemical synthetic route, which has been successfully applied for OER application in 0.1 M KOH solution. Doping of various quantities of Ni into the MnO 2 lattices improved the OER properties, and for achieving 10 mA/ cm 2 current density, the Ni-doped MnO 2 containing 0.02 M of Ni 2+ ions (coined as MnO 2 -Ni 0.002(M) ) demands only 445 mV overpotential, whereas the bare MnO 2 required 610 mV overpotential. It has been proposed that the incorporation of nickel ions into the MnO 2 lattices leads to an electron transfer from the Ni 3+ ions to Mn 4+ , which in turn facilitates the Jahn−Teller distortion in the Mn−O octahedral unit. This electron transfer and the creation of a structural disorder in the Mn sites result in the improvization of the OER properties of the MnO 2 materials.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancement of the OER Kinetics of the Less-Explored α-MnO₂ via Nickel Doping Approaches in Alkaline Medium

et al. 2021

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“…75,80–84 Ultimately, this can create manganese cation defects 19 along with oxygen vacancies, 80,84,85 which are considered to be catalytically active sites towards the ORR of MnO 2 . 86–91…”

Section: Resultsmentioning

confidence: 99%

Experimental correlation of Mn³⁺cation defects and electrocatalytic activity of α-MnO₂– an X-ray photoelectron spectroscopy study

et al. 2022

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“…Compared with other reducing agents, hydrogen‐mediated reduction offers high controllability. [ 97 ] Moreover, the reaction with hydrogen leaves only OVs behind without causing other variations in the composition, as reflected from Equation ()

MO + x {normalH}_{2} \to {MO}_{1 - x} + \frac{x}{2} {normalH}_{2} O

…”

Section: Synthetic Approaches Of Oxygen‐deficient Mosmentioning

confidence: 99%

Oxygen‐Deficient Metal Oxides for Supercapacitive Energy Storage: From Theoretical Calculation to Structural Regulation and Utilization

Wan

Wang

et al. 2022

Adv Energy and Sustain Res

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Supercapacitors (SCs) have attracted considerable research interest because of their complementary role to dominated lithium-ion batteries (LIBs) for powering the electrified society. [1] In contrast to the bulk-involved reactions for energy storage in LIBs, SCs mainly store charges in the electric double layers (EDLs) via electrostatic adsorption where highly porous and conductive materials, for example, activated carbons, are needed. [2] This storage mechanism allows SCs to exhibit excellent rate capability, long cyclic life, and high safety; therefore, it is indispensable in many fields. [3] However, despite these advantages, the limited charge storage space within electrode materials considerably restricts the energy density of SCs. To overcome this limitation, tremendous efforts have been devoted to the search for electrode materials that employ alternative charge-storage mechanisms that can improve energy storage. [4] Some metal oxides (MOs) can afford extremely fast surface redox reactions which compare favorably with those of electrostatic charge adsorption at the EDLs. Although these processes are faradaic in nature, they show an excellent rate capability that is similar to that of the EDL charge storage in the porous carbon electrodes of current SCs. Then, these MOs are defined as pseudocapacitive materials, and they can improve the energy density of current SCs. [5] The theoretical capacitance of the MO-based electrodes can be calculated using Equation (1) [6] Cwhere n, F, M, and V represent the number of transferred electrons, Faraday constant (C mol À1 ), the molar mass of the MOs (g mol À1 ), and operating voltage window (V), respectively. The specific capacitance of the typical MO electrode materials is summarized in Table 1.The MOs should have suitable electronic structures, desired electrical conductivity, and sufficient active sites to facilitate surface redox reactions. To this end, tremendous progress has been realized via research efforts in recent decades. [7] Heteroatomdoping has been widely used to engineer electronic structures. [8] Zeng et al. [9] synthesized a Ti-doped Fe 2 O 3 @poly

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Rich Surface Oxygen Vacancies of MnO₂ for Enhancing Electrocatalytic Oxygen Reduction and Oxygen Evolution Reactions

Cited by 40 publications

References 52 publications

Enhancement of the OER Kinetics of the Less-Explored α-MnO₂ via Nickel Doping Approaches in Alkaline Medium

Enhancement of the OER Kinetics of the Less-Explored α-MnO₂ via Nickel Doping Approaches in Alkaline Medium

Experimental correlation of Mn³⁺cation defects and electrocatalytic activity of α-MnO₂– an X-ray photoelectron spectroscopy study

Oxygen‐Deficient Metal Oxides for Supercapacitive Energy Storage: From Theoretical Calculation to Structural Regulation and Utilization

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Rich Surface Oxygen Vacancies of MnO2 for Enhancing Electrocatalytic Oxygen Reduction and Oxygen Evolution Reactions

Cited by 40 publications

References 52 publications

Enhancement of the OER Kinetics of the Less-Explored α-MnO2 via Nickel Doping Approaches in Alkaline Medium

Enhancement of the OER Kinetics of the Less-Explored α-MnO2 via Nickel Doping Approaches in Alkaline Medium

Experimental correlation of Mn3+cation defects and electrocatalytic activity of α-MnO2– an X-ray photoelectron spectroscopy study

Oxygen‐Deficient Metal Oxides for Supercapacitive Energy Storage: From Theoretical Calculation to Structural Regulation and Utilization

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Rich Surface Oxygen Vacancies of MnO₂ for Enhancing Electrocatalytic Oxygen Reduction and Oxygen Evolution Reactions

Enhancement of the OER Kinetics of the Less-Explored α-MnO₂ via Nickel Doping Approaches in Alkaline Medium

Enhancement of the OER Kinetics of the Less-Explored α-MnO₂ via Nickel Doping Approaches in Alkaline Medium

Experimental correlation of Mn³⁺cation defects and electrocatalytic activity of α-MnO₂– an X-ray photoelectron spectroscopy study