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Joint Redox Mechanism of Water Synthesis in H2 and O2 Mixture in the Presence of a Series of Metal Oxides


This article describes a joint redox mechanism that, using the example of water synthesis in the presence of certain metal oxides, explains the important thermodynamic features of this mechanism. This study is based on a comparison of the total enthalpy of the formation of ΔfHT redox reaction components with the reaction energy E spent when its temperature rises. Taking into account the number of moles of the resulting products of the reduction-oxidative reaction (atoms and molecules), the reaction mode (equimolar and isobaric), and the law of conservation of energy, these values should be equal. Analysis of a number of reactions differing in metal oxides (Ag2O, NiO, PtO2) and reducing gases (H2, CO, SO2), taking into account some self-cooling of the oxides during their reduction confirmed these expectations. The theoretical estimates are in reliable agreement with the experimental data. As a result of our research, the 200-year-old mystery of water synthesis, described by Sir Humphrey Davy in 1817, was solved by us based on the modern physicochemical concepts, not related to catalysis.

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The authors are grateful to Vladimir L’vov and Elena Tyurina for their help in preparing the article.


The research was carried out with the support of the Russian Federation Ministry of Science and Higher Education as part of a state assignment of the Institute of Chemistry of the Russian Academy of Sciences (topic no. 0081-2022-0008).

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Correspondence to B. V. L’vov or V. L. Ugolkov.

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L’vov, B.V., Ugolkov, V.L. Joint Redox Mechanism of Water Synthesis in H2 and O2 Mixture in the Presence of a Series of Metal Oxides. Glass Phys Chem 48, 78–83 (2022).

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  • redox mechanism
  • water synthesis
  • heterogeneous catalysis
  • enthalpy of formation
  • molar enthalpy, reaction energy