Display options
Cite
Rodriguez JA, Hanson JC, Frenkel AI, et al. Experimental and theoretical studies on the reaction of H(2) with NiO: role of O vacancies and mechanism for oxide reduction. J Am Chem Soc. 2002;124(2):346-54doi: 10.1021/ja0121080.
Rodriguez, J. A., Hanson, J. C., Frenkel, A. I., Kim, J. Y., & Pérez, M. (2002). Experimental and theoretical studies on the reaction of H(2) with NiO: role of O vacancies and mechanism for oxide reduction. Journal of the American Chemical Society, 124(2), 346-54. https://doi.org/10.1021/ja0121080
Rodriguez, José A, et al. "Experimental and theoretical studies on the reaction of H(2) with NiO: role of O vacancies and mechanism for oxide reduction." Journal of the American Chemical Society vol. 124,2 (2002): 346-54. doi: https://doi.org/10.1021/ja0121080
Rodriguez JA, Hanson JC, Frenkel AI, Kim JY, Pérez M. Experimental and theoretical studies on the reaction of H(2) with NiO: role of O vacancies and mechanism for oxide reduction. J Am Chem Soc. 2002 Jan 16;124(2):346-54. doi: 10.1021/ja0121080. PMID: 11782187.
Copy Download .nbib Format: NLM
Share it on

J Am Chem Soc. 2002 Jan 16;124(2):346-54. doi: 10.1021/ja0121080.

Experimental and theoretical studies on the reaction of H(2) with NiO: role of O vacancies and mechanism for oxide reduction.

Journal of the American Chemical Society

José A Rodriguez, Jonathan C Hanson, Anatoly I Frenkel, Jae Y Kim, Manuel Pérez

Affiliations

  1. Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA. [email protected]

PMID: 11782187 DOI: 10.1021/ja0121080

Abstract

Reduction of an oxide in hydrogen is a method frequently employed in the preparation of active catalysts and electronic devices. Synchrotron-based time-resolved X-ray diffraction (XRD), X-ray absorption fine structure (NEXAFS/EXAFS), photoemission, and first-principles density-functional (DF) slab calculations were used to study the reaction of H(2) with nickel oxide. In experiments with a NiO(100) crystal and NiO powders, oxide reduction is observed at atmospheric pressures and elevated temperatures (250-350 degrees C), but only after an induction period. The results of in situ time-resolved XRD and NEXAFS/EXAFS show a direct NiO-->Ni transformation without accumulation of any intermediate phase. During the induction period, surface defect sites are created that provide a high efficiency for the dissociation of H(2). A perfect NiO(100) surface, the most common face of nickel oxide, exhibits a negligible reactivity toward H(2). The presence of O vacancies leads to an increase in the adsorption energy of H(2) and substantially lowers the energy barrier associated with the cleavage of the H-H bond. At the same time, adsorbed hydrogen can induce the migration of O vacancies from the bulk to the surface of the oxide. A correlation is observed between the concentration of vacancies in the NiO lattice and the rate of oxide reduction. These results illustrate the complex role played by O vacancies in the mechanism for reduction of an oxide. The kinetic models frequently used to explain the existence of an induction time during the reduction process can be important, but a more relevant aspect is the initial production of active sites for the rapid dissociation of H(2).

Publication Types