Low temperature synthesis of NiO/CoO nanostructures to enhance their low temperature oxygen reduction catalysis. (October 2022)

• Record Type: Journal Article
• Authors: Dan-dan, Yu; Yong, Zhang; Hong-quan, Yu; Hong, Zhao
• Is Part Of: Micron. Volume 161(2022)
• Publication Date: 2022-10
• Subjects: Low temperature -- Oxygen reduction reaction (ORR) -- Stepped active sites -- Strain effect -- First-principles calculation -- NiO/CoO catalysts; Microscopy -- Periodicals; Electron Probe Microanalysis -- Periodicals; Microscopy -- Periodicals; Microscopie -- Périodiques; Microscopy; Periodicals; 502.82
• DOI: 10.1016/j.micron.2022.103326
• Languages: English
• ISSNs: 0968-4328

Abstract

Abstract: "Thermal expansion and cold contraction" are common occurrences in nature. Resulting from "thermal expansion and cold contraction" reaction, strain effect is created, which affects the oxygen reduction reaction (ORR) activities of fuel cell catalysts. Nevertheless, the "thermal expansion and cold contraction" effects of catalysts have rarely been investigated. Herein, the influence of "thermal expansion and cold contraction" strains upon ORR activities of NiO/CoO catalysts is investigated. Experimental and first-principles calculations reveal that, when NiO/CoO are synthesized and used as catalysts under low temperature ice/water environment, there is virtually no strain effect created, and abundant active sites contribute to the good low temperature ORR activities of NiO/CoO catalysts (onset potential: 0.736 V, halfwave potential: 0.659 V). When high temperature synthesized NiO/CoO catalysts are used at low temperature, however, small amounts of active sites are created. Moreover, the adsorption activity of NiO(222) and CoO(311) stepped active sites are weakened by compressive strain of lattice contraction, which reduces their ORR activities. The "low temperature synthesis and low temperature catalysis" route proposed by this paper paves a new road for the synthesis and design of low-temperature catalysts. Highlights: A "low temperature synthesis and low temperature catalysis" route is proposed to grow low temperature NiO/CoO catalysts. "Thermal expansion and cold contraction" of NiO/CoO catalysts affects their oxygen reduction reaction (ORR) activities. The ORR activities of NiO/CoO catalysts are decreased by compressive strain of lattice contraction.