【NHF Forum No.157】Moving from Environmental Remediation to Energy: What We Learned about Nb2O5 Photocatalysts

报 告 人：Caue Ribeiro 教授， Embrapa (Brazilian Agricultural Research Corporation)

报告题目：Moving from Environmental Remediation to Energy: What We Learned about Nb2O5 Photocatalysts

时     间：2018年7月17日（周二）15:00-17:00

地     点：国家纳米科学中心南楼二层中会议室

邀 请 人：贺涛 研究员

报告摘要:

Literature has many examples of semiconducting materials as photocatalysts for degradation of water contaminants. Despite a large concentration in TiO2 andTiO2-based materials, other semiconductors have gained attention due specific aspects that promote higher photoactivity (e.g., in visible light, reduced electron-hole recombination) but few was done to understand the role of surface acidity in these process. A study-of-case is Nb2O5, which is a wide-band semiconductor, with similar electronic properties to TiO2 but with very acidic surface. This feature indicates that the way that Nb2O5 plays its photooxidative role is different from other semiconductors, depending of the equilibrium of charges in degradation medium. We developed a method to produce this semiconductor through a peroxocomplex formation, which is further de-stabilized in hydrothermal conditions to promote oxide precipitation in a controllable manner. This synthesis, despite very simple, was easily controlled to produce different surface features, as well as heterostructures based on T/TT Nb2O5 phases. This material has showed a considerable photoactivity in UV light for degradation of different pollutants, but also a good versatility: the mixture with g-C3N4 (a polymeric semiconductor) in adequate pH conditions has lead to a self-organized heterostructure, with also remarkable photoactivity. However, these materials did not present only photooxidative activity: measuring their potential for photoreduction, we have observed that modifications with other semiconductors (e.g. CuO) allows this system to promote Cr(VI) reduction and, more interesting, promote the CO2 reduction to CO in significant yields, despite the acidic surface suggest that this reaction would not be favored. Therefore, the knowledge about this material for environmental remediation is now opening other application for this material in renewable energy production, which needs be deeper investigated.

报告人简历：

Caue Ribeiro is Senior Researcher at Embrapa (Brazilian Agricultural Research Corporation). He is materials engineer (Federal University at Sao Carlos, UFSCar, Brazil, 1999) and PhD in Physical Chemistry (UFSCar, 2005). After a period in the private sector, he joined Embrapa as Full Researcher in Instrumentation Center in 2007. From 2015 to 2017 he serve as Deputy Head of Technology Transference, responsible for institutional relationship to private sector, involving prospection of partners interested in patent transfer, agreements for joint research, intellectual property, market analyses and contracts for funding research by private companies. Currently he is the coordinator of Agronano Network – a research network for nanotechnological applications in agriculture, involving about 150 researchers in Brazil and abroad (https://www.embrapa.br/nano). His primary research interests include the development of synthesis routes to produce heterogeneous catalysts (mainly inorganic nanoparticles) for water decontamination and energy production, and development of nanocomposites for slow/controlled release in agriculture. He have published > 140 papers, with > 2,800 citations (H-index 29). In 2017 he received the Alexander von Humboldt Fellowship as Experienced Researcher, to start in 2018/2019 as Visiting Researcher in Forschungszentrum Jülich (Germany). In 2018 he received the CAS President's International Fellowship Initiative (PIFI) for Visiting Scientists, to do research in the National Center for Nanoscience and Technology (NCNST) during July/August 2018 hosted by Prof. Dr. Tao He.

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