Active Mixed‐Valent MnO<sub><i>x</i></sub> Water Oxidation Catalysts through Partial Oxidation (Corrosion) of Nanostructured MnO Particles

Indra, Arindam; Menezes, Prashanth W.; Zaharieva, Ivelina; Baktash, Elham; Pfrommer, Johannes; Schwarze, Michael; Dau, Holger; Drieß, Matthias

doi:10.1002/anie.201307543

Cited by 277 publications

(240 citation statements)

References 39 publications

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“…Extensive investigation of the EXAFS structure of the catalyst revealed m-oxido-bridged MnÀOÀMn bonds and the flexibility of layered structure effecting the enhancement of water oxidation activity. [69] Our recent activities in the area of biomimetic water oxidation and continuous search for highly active water-oxidizing catalysts on larger scale prompted us to explore a singlesource precursor (SSP) approach. The advantages of SSP routes are immense in comparison to the arduous classical approach that comprises a low temperature synthesis and the precise control of the composition with a maximum of dispersion of the elements on the atomic level and of the oxidation states of the metals of the heterogeneous catalysts.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Manganese Oxides as Highly Active Water Oxidation Catalysts: A Boost from Manganese Precursor Chemistry

et al. 2014

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We present a facile synthesis of bioinspired manganese oxides for chemical and photocatalytic water oxidation, starting from a reliable and versatile manganese(II) oxalate single-source precursor (SSP) accessible through an inverse micellar molecular approach. Strikingly, thermal decomposition of the latter precursor in various environments (air, nitrogen, and vacuum) led to the three different mineral phases of bixbyite (Mn2 O3 ), hausmannite (Mn3 O4 ), and manganosite (MnO). Initial chemical water oxidation experiments using ceric ammonium nitrate (CAN) gave the maximum catalytic activity for Mn2 O3 and MnO whereas Mn3 O4 had a limited activity. The substantial increase in the catalytic activity of MnO in chemical water oxidation was demonstrated by the fact that a phase transformation occurs at the surface from nanocrystalline MnO into an amorphous MnOx (1

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Section: Introductionmentioning

confidence: 99%

Nanostructured Manganese Oxides as Highly Active Water Oxidation Catalysts: A Boost from Manganese Precursor Chemistry

et al. 2014

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“…Currently, one of the biggest challenges is to develop a cheap and efficient catalyst for the former reaction with a low overpotential, which is still needed to overcome the kinetic barriers (already lowered by the catalyst) along the path from reactants to products. Birnessite, similar to the oxygen-evolving complex in Photosystem II for photosynthesis in regard to the coexistence of Mn(III) (nominal Mn 3+ ) and Mn(IV) (nominal Mn 4+ ) within its structure (1)(2)(3), has already shown a moderate catalytic performance with the overpotentials reported from 0.6 V to 0.8 V (4)(5)(6)(7)(8).…”

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Redox properties of birnessite from a defect perspective

Peng

McKendry

Ding

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Birnessite, a layered-structure MnO 2 , is an earth-abundant functional material with potential for various energy and environmental applications, such as water oxidation. An important feature of birnessite is the existence of Mn(III) within the MnO 2 layers, accompanied by interlayer charge-neutralizing cations. Using first-principles calculations, we reveal the nature of Mn(III) in birnessite with the concept of the small polaron, a special kind of point defect. Further taking into account the effect of the spatial distribution of Mn(III), we propose a theoretical model to explain the structure-performance dependence of birnessite as an oxygen evolution catalyst. We find an internal potential step which leads to the easy switching of the oxidation state between Mn(III) and Mn(IV) that is critical for enhancing the catalytic activity of birnessite. Finally, we conduct a series of comparative experiments which support our model.birnessite MnO 2 | small polaron | catalysis | water oxidation P hotoelectrochemical (PEC) splitting of water into H2 and O2 (artificial photosynthesis) provides an attractive way to harvest solar energy. The process consists of the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), both of which are facilitated with catalysts in practice. Currently, one of the biggest challenges is to develop a cheap and efficient catalyst for the former reaction with a low overpotential, which is still needed to overcome the kinetic barriers (already lowered by the catalyst) along the path from reactants to products. Birnessite, similar to the oxygen-evolving complex in Photosystem II for photosynthesis in regard to the coexistence of Mn(III) (nominal Mn 3+ ) and Mn(IV) (nominal Mn 4+ ) within its structure (1-3), has already shown a moderate catalytic performance with the overpotentials reported from 0.6 V to 0.8 V (4-8).Birnessite has the general formula Mx MnO2·1.5(H2O), composed of layers of edge-sharing MnO6 octahedra as shown in Fig. 1 for the hexagonal phase, and an interlayer of randomly distributed water molecules and metal (M) cations (like K + , Na + , and Ca 2+ ). With the charge balanced by the interlayer cations, some of the Mn cations within the MnO2 layer are reduced from Mn(IV) to Mn(III). The coexistence of Mn(IV) and Mn(III), and further the "balanced equilibrium" or low energy barrier between them, has been suspected to be a critical factor for its catalytic activity (1). The importance of the high-spin Mn(III), through its e 1 g electronic configuration, has been realized in other manganese oxides for OER catalysis (2, 9) and also follows the design principle of Suntivich et al. (10) that a near-unity eg occupancy may imply good OER catalytic activity. This easy switching of the oxidation state is also a typical behavior for the transition metal cation undergoing back and forth changes between several oxidation states in OER catalysts during the water oxidation cycle (11-13). OER catalysts like Co-and Ni-doped hematite (12) and cobalt oxides (13), as well as ...

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“…14,31,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Low stability issues of organic ligand based catalysts are circumvented in such POM based catalysts that also have higher stability. Another advantage of using POM based catalysts is that they can be used to form composite with di®erent electro active surfaces.…”

Section: Introductionmentioning

confidence: 99%

Photochemical Water Oxidation Using {PMo12O40@Mo72Fe30}_n Based Soft Oxometalate

Das

Roy

2017

J. Mol. Eng. Mater.

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Finding an alternative energy resource which can produce clean energy at a low cost is one of the major concerns of our times. The conversion of light energy into chemical energy is one key step forward in the direction. With that end in view photochemical water oxidation to produce oxygen plays a crucial role. In the present paper we have synthesized a soft oxometalate fPMo 12 O 40 @Mo 72 Fe 30 g n (1) from its well-known precursor polyoxometalate constituent [Muller et al., Chem. Commun. 1, 657 (2001)]. It is known that in the matter of catalysis, high surface area, possibility of heterogenization, recoverability makes soft oxometalates (SOMs) attractive as catalytic materials. Here we exploit such advantages of SOMs. The SOM based material acts as an active catalyst for photochemical water oxidation reaction with a maximum turnover number of 20256 and turnover frequency of 24.11 min À1 . The catalyst material is stable under photochemical reaction conditions and therefore can be reused for multiple photo catalytic water oxidation reaction cycles.

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Active Mixed‐Valent MnO_x Water Oxidation Catalysts through Partial Oxidation (Corrosion) of Nanostructured MnO Particles

Cited by 277 publications

References 39 publications

Nanostructured Manganese Oxides as Highly Active Water Oxidation Catalysts: A Boost from Manganese Precursor Chemistry

Nanostructured Manganese Oxides as Highly Active Water Oxidation Catalysts: A Boost from Manganese Precursor Chemistry

Redox properties of birnessite from a defect perspective

Photochemical Water Oxidation Using {PMo12O40@Mo72Fe30}_n Based Soft Oxometalate

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Active Mixed‐Valent MnOx Water Oxidation Catalysts through Partial Oxidation (Corrosion) of Nanostructured MnO Particles

Cited by 277 publications

References 39 publications

Nanostructured Manganese Oxides as Highly Active Water Oxidation Catalysts: A Boost from Manganese Precursor Chemistry

Nanostructured Manganese Oxides as Highly Active Water Oxidation Catalysts: A Boost from Manganese Precursor Chemistry

Redox properties of birnessite from a defect perspective

Photochemical Water Oxidation Using {PMo12O40@Mo72Fe30}n Based Soft Oxometalate

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Active Mixed‐Valent MnO_x Water Oxidation Catalysts through Partial Oxidation (Corrosion) of Nanostructured MnO Particles

Photochemical Water Oxidation Using {PMo12O40@Mo72Fe30}_n Based Soft Oxometalate