MOF-derived NiO/CeO 2 heterojunction: a photocatalyst for degrading pollutants and hydrogen evolution
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MOF-derived NiO/CeO2 heterojunction: a photocatalyst for degrading pollutants and hydrogen evolution Pengfei Li1,2, Ming Zhang1,2,* Bo Wang1,2, and Hui Yan1,2
, Xuewei Li1,2, Chao Wang1,2, Ruzhi Wang1,2,
1
The Key Laboratory of Advanced Functional Materials, Ministry of Education of China, Beijing University of Technology, Beijing 100124, People’s Republic of China 2 College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, People’s Republic of China
Received: 3 May 2020
ABSTRACT
Accepted: 17 August 2020
A NiO/CeO2 p–n heterojunction with the hierarchically porous microspheres was fabricated by annealing the precursor of the nickel/cerium mixed-metal metal–organic frameworks. The morphologies, microstructures, composition, specific surface area, photogenerated electron–hole pair separation/transfer, and photocatalytic activities were characterized for all acquired catalysts. The photodegradation rates of organic dyes including methyl orange and methylene blue were investigated under ultraviolet light. The NiO/CeO2 heterojunctions showed a much higher photocatalytic performance than that of pure NiO and CeO2. Among all photocatalysts NiO/CeO2-3 presented the best photocatalytic activity, i.e., the degradation of MO was 2.6 times higher than pure NiO under ultraviolet light, and the hydrogen generation with the rate of about 29.6 lmol h-1 g-1. The improved photocatalytic performance could be ascribed to the formation of the NiO/CeO2 p–n heterojunction, which is beneficial for effective separation and fast transfer of the photoexcited electron–hole pairs.
Published online: 27 August 2020
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Springer Science+Business
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Introduction Booming investigations on semiconductor-based photocatalysts, which are regarded as green technologies, have attracted more and more attentions because of their impressive advantages, i.e., ease of preparation, low cost, and non-toxic nature, and potential applications in environmental protection
and hydrogen production by splitting water in the past few decades [1–3]. Among a number of typical transition metal-oxide semiconductors (e.g., TiO2 [4], ZnO [5, 6], NiO [7]), which have been studied intensively for photocatalytic applications, nickel oxide (NiO) is particularly suitable for photocatalytic reaction due to the fact that it is a p-type semiconductor with a bandgap of about 3.43 eV [8]. However, the fast recombination of photogenerated electron–
Handling Editor: Christopher Blanford.
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https://doi.org/10.1007/s10853-020-05123-2
15931
J Mater Sci (2020) 55:15930–15944
hole pairs reduces the corresponding quantum efficiency seriously and then limits its photocatalytic activity. Recently, it was reported that constructing heterojunctions between NiO and other metal oxides with appropriate band positions could enhance the photocatalytic activity of metal-oxide-semiconductor photocatalysts efficiently [9–13]. Additionally, constructing p–n junctio
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