Photoactivity and Stability Co-Enhancement: When Localized Plasmons Meet Oxygen Vacancies in MgO

Zhengqing Liu; Ziyang Lu; Michel Bosman; Na Li; Terry J Frankcombe; Guohua Jia; Antonio Tricoli; Yun Liu; Yaping Du; Zongyou Yin

doi:10.1002/smll.201803233

Photoactivity and Stability Co-Enhancement: When Localized Plasmons Meet Oxygen Vacancies in MgO

Small. 2018 Nov;14(48):e1803233. doi: 10.1002/smll.201803233. Epub 2018 Oct 17.

Authors

Zhengqing Liu¹, Ziyang Lu², Michel Bosman³, Na Li⁴, Terry J Frankcombe⁵, Guohua Jia⁶, Antonio Tricoli⁷, Yun Liu², Yaping Du¹, Zongyou Yin²

Affiliations

¹ School of Materials Science and Engineering, National Institute for Advanced Materials, Center for Rare Earth and Inorganic Functional Materials, Nankai University, Tianjin, 300350, P. R. China.
² Research School of Chemistry, The Australian National University, Canberra, ACT, 2601, Australia.
³ Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore, 117575, Singapore.
⁴ Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
⁵ School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT, 2600, Australia.
⁶ Nanochemistry Research Institute, Department of Chemistry, Curtin University, Perth, Western Australia, 6102, Australia.
⁷ Research School of Engineering, The Australian National University, Canberra, ACT, 2601, Australia.

PMID: 30334350
DOI: 10.1002/smll.201803233

Abstract

Durability is still one of the key obstacles for the further development of photocatalytic energy-conversion systems, especially low-dimensional ones. Encouragingly, recent studies show that nanoinsulators such as SiO₂ and MgO exhibit substantially enhanced photocatalytic durability than the typical semiconductor p25 TiO₂ . Extending this knowledge, MgO-Au plasmonic defect nanosystems are developed that combine the stable photoactivity from MgO surface defects with energy-focusing plasmonics from Au nanoparticles (NPs), where Au NPs are anchored onto monodispersed MgO nanotemplates. Theoretical calculations reveal that the midgap defect (MGD) states in MgO are generated by oxygen vacancies, which provide the main avenues for upward electron transitions under photoexcitation. These electrons drive stable proton photoreduction to H₂ gas via water splitting. A synergistic interaction between Au's localized plasmons and MgO's oxygen vacancies is observed here, which enhances MgO's photoactivity and stability simultaneously. Such co-enhancement is attributed to the stable longitudinal-plasmon-free Au NPs, which provide robust hot electrons capable of overcoming the interband transition barrier (≈1.8 eV) to reach proton reduction potential for H₂ generation. The demonstrated plasmonic defect nanosystems are expected to open a new avenue for developing highly endurable photoredox systems for the integration of multifunctionalities in energy conversion, environmental decontamination, and climate change mitigation.

Keywords: co-enhancement of photoactivity and stability; oxygen vacancies; plasmonic defect nanosystems; surface plasmon.

Abstract

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