Two-stage electrolysis of H2O and CO2 to methanol: CO2-to-methane reduction at the cathode and subsequent methane-to-methanol oxidation at the anode

Hibino, Takashi; Kobayashi, Kazuyo; Nagao, Masahiro; Dongwen, Zhou; Chen, Siyuan

doi:10.1039/d2ta04011e

Cited by 8 publications

(8 citation statements)

References 60 publications

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“…Our previous XPS study of the Pt anode after DC electrolysis of humidified methane indicated that the Pt was oxidized to high-valence states (i.e., PtO, PtO x , and PtO 2 ) (Figure a) . By contrast, compared with the deconvoluted spectra after DC electrolysis of humidified methane, those after DC electrolysis of unhumidified methane showed lower intensities of double peaks indexed to PtO and PtO x and the disappearance of the PtO 2 peak (Figure b).…”

Section: Resultsmentioning

confidence: 90%

“…The Sn 0.9 In 0.1 P 2 O 7 powder was synthesized using a previously reported method. 20 Sn 0.9 In 0.1 P 2 O 7 powder (1 g) was mixed with 0.04 g of PTFE powder using a mortar and pestle, and the resultant mixture was cold-rolled to a thickness of 200 μm using a laboratory rolling mill. Anodes were prepared by depositing Pt particles onto the surface of the electrolyte by sputtering (Sanyu Electron, SC-701MkII) under an Ar atmosphere (Figure S1).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…This method enabled the amount of Pt to be adjusted through modification of the sputtering time without changing the crystallite size. 20 One of various metals (Pd, Ag, Au, Co, or Fe) was further sputtered onto the surface of the Pt anode. The purity of the metal targets (Nilaco) was greater than 99.9%.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Nevertheless, Pt is overoxidized to PtO x at potentials greater than its redox potential (Pt 2+ /Pt + 1.18 V; PtO/Pt + 0.98 V), 23 which leads to degradation of the Pt electrocatalyst for methane oxidation. 20 This issue might be avoided by changing the polarity of the electrodes periodically during electrolysis. 24 and C−H phosphorylation reactions, 25 respectively.…”

Section: ■ Introductionmentioning

confidence: 99%

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Alternating Current Electrolysis for Individual Synthesis of Methanol and Ethane from Methane in a Thermo-electrochemical Cell

et al. 2023

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The individual synthesis of methanol and ethane from methane was investigated using a thermo-electrochemical cell in gas flow mode over the temperature range of 150–200 °C. Methane was directly oxidized at an anode consisting of sub-10 nm Pt and Fe particles. In the electrolysis of humidified methane, methanol was produced through the formation of active oxygen intermediates from water vapor. In the electrolysis of unhumidified methane, ethane was produced via the dissociation of C–H bonds, followed by dimerization of the resultant •CH3 radicals. However, the formation rates for the target products decreased with time during electrolysis because of overoxidation of the anode by the direct-current (DC) voltage. The alternating current (AC) electrolysis of methane avoided this problem. Under optimized AC polarization conditions at a square waveform voltage of ±2.5 V with a pulse time of 5 s, this cell generated methanol and ethane at rates of 5.1 × 10–5 mol m–2 s–1 (92 mmol gcat –1 h–1) and 3.8 × 10–5 mol m–2 s–1 (69 mmol gcat –1 h–1), respectively, without a substantial loss of activity during continuous electrolysis.

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Section: Resultsmentioning

confidence: 90%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Alternating Current Electrolysis for Individual Synthesis of Methanol and Ethane from Methane in a Thermo-electrochemical Cell

et al. 2023

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“…Indeed, our DFT calculations on CoOOH show that for a potential below ∼1 V, desorption of methanol coupled with adsorption of OH – on the Co site is thermodynamically favored vs further oxidation to methoxy, so that electrocatalytic oxidation with the control of the potential could open a possibility of selective formation of methanol. Moving to the gas phase, humidified membrane electrode assemblies could be a viable approach to electrochemical methane to methanol transformation systems, provided the four conditions above of high methane transport, high metal oxide catalyst conductivity, fast methanol desorption relative to overoxidation, and fast methanol product collection are met. − …”

Section: Discussionmentioning

confidence: 99%

Electrochemical Oxidation of Methane to Methanol on Electrodeposited Transition Metal Oxides

et al. 2023

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Electrochemical partial oxidation of methane to methanol is a promising approach to the transformation of stranded methane resources into a high-value, easy-to-transport fuel or chemical. Transition metal oxides are potential electrocatalysts for this transformation. However, a comprehensive and systematic study of the dependence of methane activation rates and methanol selectivity on catalyst morphology and experimental operating parameters has not been realized. Here, we describe an electrochemical method for the deposition of a family of thin-film transition metal (oxy)hydroxides as catalysts for the partial oxidation of methane. CoO x , NiO x , MnO x , and CuO x are discovered to be active for the partial oxidation of methane to methanol. Taking CoO x as a prototypical methane partial oxidation electrocatalyst, we systematically study the dependence of activity and methanol selectivity on catalyst film thickness, overpotential, temperature, and electrochemical cell hydrodynamics. Optimal conditions of low catalyst film thickness, intermediate overpotentials, intermediate temperatures, and fast methanol transport are identified to favor methanol selectivity. Through a combination of control experiments and DFT calculations, we show that the oxidized form of the as-deposited (oxy)hydroxide catalyst films are active for the thermal oxidation of methane to methanol even without the application of bias potential, demonstrating that high valence transition metal oxides are intrinsically active for the activation and oxidation of methane to methanol at ambient temperatures. Calculations uncover that electrocatalytic oxidation enables reaching an optimum potential window in which methane activation forming methanol and methanol desorption are both thermodynamically favorable, methanol desorption being favored by competitive adsorption with hydroxide anion.

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Progress of CO2 Electrochemical Methanation Using a Membrane Electrode Assembly

Matsuda,

Osawa,

Umeda

2024

Electrocatalysis

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Two-stage electrolysis of H₂O and CO₂ to methanol: CO₂-to-methane reduction at the cathode and subsequent methane-to-methanol oxidation at the anode

Abstract: Co-electrolysis of H2O and N/C sources to valuable chemicals has the potential to contribute to global warming mitigation. We here report the electrochemical conversion of H2O and CO2 into methanol...

Cited by 8 publications

References 60 publications

Alternating Current Electrolysis for Individual Synthesis of Methanol and Ethane from Methane in a Thermo-electrochemical Cell

Alternating Current Electrolysis for Individual Synthesis of Methanol and Ethane from Methane in a Thermo-electrochemical Cell

Electrochemical Oxidation of Methane to Methanol on Electrodeposited Transition Metal Oxides

Progress of CO2 Electrochemical Methanation Using a Membrane Electrode Assembly

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