A-site substitution effect of perovskite-type cobalt and manganese oxides on two-step water splitting reaction for solar hydrogen production

Kaneko, Hiroshi; Hasegawa, Takumi; Mori, Kohei

doi:10.1063/1.4984468

Cited by 2 publications

(2 citation statements)

References 32 publications

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“…Thermal reduction temperature is lowered by using mixed oxides [6], such as M x Fe 3−x O 4 where M = Mn, Co, Ni, Zn. Currently, thermochemical redox cycles operate at 1300 • C obtained using concentrated solar-thermal energy [7][8][9]. Localized temperatures well above 1000 • C can also be obtained by nonthermal plasma without affecting the catalyst, and energy efficiency can be enhanced by the imposition of pulsed power.…”

Section: Thermochemical Redox Cycle For the Production Of Hydrogen From Water And Carbon Monoxide From Carbon Dioxidementioning

confidence: 99%

Plasma Generating—Chemical Looping Catalyst Synthesis by Microwave Plasma Shock for Nitrogen Fixation from Air and Hydrogen Production from Water for Agriculture and Energy Technologies in Global Warming Prevention

Akay

2020

Catalysts

103

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Simultaneous generation of plasma by microwave irradiation of perovskite or the spinel type of silica supported porous catalyst oxides and their reduction by nitrogen in the presence of oxygen is demonstrated. As a result of plasma generation in air, NOx generation is accompanied by the development of highly heterogeneous regions in terms of chemical and morphological variations within the catalyst. Regions of almost completely reduced catalyst are dispersed within the catalyst oxide, across micron-scale domains. The quantification of the catalyst heterogeneity and evaluation of catalyst structure are studied using Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy and XRD. Plasma generating supported spinel catalysts are synthesized using the technique developed by the author (Catalysts; 2016; 6; 80) and BaTiO3 is used to exemplify perovskites. Silica supported catalyst systems are represented as M/Si = X (single catalysts) or as M(1)/M(2)/Si = X/Y/Z (binary catalysts) where M; M(1) M(2) = Cr; Mn; Fe; Co; Cu and X, Y, Z are the molar ratio of the catalysts and SiO2 support. Composite porous catalysts are synthesized using a mixture of Co and BaTiO3. In all the catalysts, structural heterogeneity manifests itself through defects, phase separation and increased porosity resulting in the creation of the high activity sites. The chemical heterogeneity results in reduced and oxidized domains and in very large changes in catalyst/support ratio. High electrical potential activity within BaTiO3 particles is observed through the formation of electrical treeing. Plasma generation starts as soon as the supported catalyst is synthesized. Two conditions for plasma generation are observed: Metal/Silica molar ratio should be > 1/2 and the resulting oxide should be spinel type; represented as MaOb (a = 3; b = 4 for single catalyst). Composite catalysts are represented as {M/Si = X}/BaTiO3 and obtained from the catalyst/silica precursor fluid with BaTiO3 particles which undergo fragmentation during microwave irradiation. Further irradiation causes plasma generation, NOx formation and lattice oxygen depletion. Partially reduced spinels are represented as MaOb–c. These reactions occur through a chemical looping process in micron-scale domains on the porous catalyst surface. Therefore; it is possible to scale-up this process to obtain NOx from MaOb for nitric acid production and H2 generation from MaOb–c by catalyst re-oxidized by water. Re-oxidation by CO2 delivers CO as fuel. These findings explain the mechanism of conversion of combustion gases (CO2 + N2) to CO and NOx via a chemical looping process. Mechanism of catalyst generation is proposed and the resulting structural inhomogeneity is characterized. Plasma generating catalysts also represent a new form of Radar Absorbing Material (RAM) for stealth and protection from radiation in which electromagnetic energy is dissipated by plasma generation and catalytic reactions. These catalytic RAMs can be expected to be more efficient in frequency independent microwave absorption.

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Section: Thermochemical Redox Cycle For the Production Of Hydrogen From Water And Carbon Monoxide From Carbon Dioxidementioning

confidence: 99%

Plasma Generating—Chemical Looping Catalyst Synthesis by Microwave Plasma Shock for Nitrogen Fixation from Air and Hydrogen Production from Water for Agriculture and Energy Technologies in Global Warming Prevention

Akay

2020

Catalysts

103

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“…Besides being low cost, abundant and environmentally friendly, it has shown higher specific capacitance as compared to other electrode materials, for instance RuO 2. 34‐36 TiO 2 primarily the rutile phase has been shown to exhibit the most attractive dielectric properties among other crystalline phases. Titanium is multivalent, indicating a higher possibility of inducing reduction‐oxidation electrochemical reactions.…”

Section: Introductionmentioning

confidence: 99%

Sol‐gel derived mixed phase (Mn, Ti)‐oxides/graphene nanoplatelets for hybrid supercapacitors

2020

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In this investigation, (Mn, Ti)-oxides were prepared using pluronic 123 templating assisted sol-gel method. Sol-A with Ti precursor in ethanol was acidified with HCl whereas sol-B containing Mn precursor was prepared in ethanol containing 5 wt% pluronic 123 surfactant. Gelation was accomplished by the addition of de-ionized water. As-prepared gels were aged for 24 hours, dried at 80 C for 12 hours and calcined at 500 C to 1200 C for 5 hours to obtain powdered electrode materials, which were analyzed by x-ray diffraction, scanning electron microscopy/energy-dispersive x-ray, and Brunauer-Emmett-Teller (BET) surface area analysis. Hybrid supercapacitors were fabricated using the sol-gel derived (Mn, Ti)-oxides and Gr-nanoplatelets electrodes with aqueous KOH (potassium hydroxide) as electrolyte. Fabricated supercapacitors were charged with 2.0 V and 0.01 A for 10 minutes. Charged supercapacitors were tested via cyclic voltammetry to determine specific capacitance. For the powdered materials prepared with Mn:Ti at 65:35 wt% and calcined at 500 C, x-ray diffraction analysis revealed the presence of TiO 2-rutile, Mn 2 O 3 and Mn 3 O 4 as 20%, 60%, and 18%, respectively. At higher calcination temperature, TiO 2-rutile and Mn 2 O 3 phases were found to be absent with the presence of higher perovskite (TiMnO 3) phase. Both pore volume and BET specific surface area was found to decrease with increase in calcination temperature. The specific capacitance was found be dependent on Mn:Ti wt% used to prepare the powdered materials as well as the calcination conditions. The gel prepared with Mn:Ti of 30:70 wt% followed by 2-step calcination yielded a maximum specific capacitance.

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A-site substitution effect of perovskite-type cobalt and manganese oxides on two-step water splitting reaction for solar hydrogen production

Abstract: Development and experimental study for hydrogen production from the thermochemical two-step water splitting cycles with a CeO 2 coated new foam device design using solar furnace system AIP Conference Proceedings 1850, 100003 (2017)

Cited by 2 publications

References 32 publications

Plasma Generating—Chemical Looping Catalyst Synthesis by Microwave Plasma Shock for Nitrogen Fixation from Air and Hydrogen Production from Water for Agriculture and Energy Technologies in Global Warming Prevention

Plasma Generating—Chemical Looping Catalyst Synthesis by Microwave Plasma Shock for Nitrogen Fixation from Air and Hydrogen Production from Water for Agriculture and Energy Technologies in Global Warming Prevention

Sol‐gel derived mixed phase (Mn, Ti)‐oxides/graphene nanoplatelets for hybrid supercapacitors

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