Talk: High-Throughput Synthesis of Metal Oxide Nanocrystals by Cathodic Corrosion and Their Use as Active Photocatalysts

Talk by Dr. Paramaconi Rodriguez

School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK

Birmingham Centre for Strategic Elements & Critical Materials, University of Birmingham, Edgbaston, UK

Growing energetic demands, in conjunction with the ever-growing consensus surrounding the increasing adverse effects of climate change and global warming, have led to much research dedication to the development of renewable energy technologies. A hydrogen economy has long been sought after, but with most the earth’s hydrogen stored in water and the main source of hydrogen production involving the burning of fossil fuels, a widely applicable alternative is required.

Among the properties of the nanocatalyst commonly used in green energy technology, i.e. hydrogen economy and CO2 conversion, the composition and surface structure of the nanomaterials are perhaps the most important parameters since the chemical and physical properties of the materials are correlated with the electronic states. Nanoscale photocatalysts are desired to overcome the limitations surrounding the low natural abundance of solar UV light by modifying the semiconductor band gaps to harness more of the visible spectrum and minimize ion carrier migration distances. Current state-of-the-art metal oxide photocatalysts include TiO2, FeTiO3, H2WO4, BiVO4 and their metal-doped analogues. To date, the most common ways to prepare these catalysts are solution-based methods such as solvothermal syntheses. However these methods are time-consuming and commonly demand the utilization of organic solvents, surfactants, or capping materials that add complexity and cost. The use of capping agents can also negatively affect the catalytic activity by blocking active sites. To minimize the effect of contaminants, these methods implement high-temperature protocols that often result in large particle-size distribution and a lack in control of the surface structure.

The widespread use and commercialization of catalyst for this technologies requires high-throughput, robust, efficient, safe, and inexpensive fabrication procedures. I will introduce the use of the cathodic corrosion method1-4 for the synthesis of metal oxide nanoparticles, including TiO2, BiVO4 and HWO4. Here we demonstrate that the particle size and shape of mixed transition metal oxide semiconductor nanoparticles can be tuned by changing the synthesis conditions.5 This has resulted in an effective way to change the photocatalytic properties of the nanomaterials. The structure-reactivity relationship for the photocatalytic water oxidation will be presented.

Figure 1. (A-D) TEM images of H2WO4 and TiO2 nanoparticles synthesized by cathodic corrosion using varying conditions. (E) UV-vis absorption spectrum of the H2WO4 and TiO2 nanoparticles in figure (A). (F) Relationship between the photocatalytic activity and the synthesis conditions (particle size/surface structure). (G) TiO2, BiVO4 and FeTiO3 nanoparticles prepared with the cathodic corrosion method.

I will also present a combinatorial approach for the synthesis of new mixed-metal oxide nanoparticles. First, I will report the synthesis of binary and ternary bulk alloys with well-controlled composition by the Direct Laser Fabrication.6, 7 The process is followed by the synthesis of metal oxide nanoparticles with well-defined and homogenous composition using the cathodic corrosion method. I will present the structural characterization of different mixed metal oxide nanoparticles and their photocatalytic activity towards the Oxygen Evolution Reaction.

1. E. Bennett, et al. ACS Catalysis 2016, 6, (3), 1533.

2. M. R. Duca, Paramaconi; Yanson, Alex; Koper, M.T.M. Topics in catalysis 2014, 57, 255.

3. A. I. Yanson, et al. Angewandte Chemie International Edition 2011, 50, (28), 6346.

4. P. Rodriguez, et al. J. Am. Chem. Soc. 2011, 133, (44), 17626.

5. M. L. Kromer, et al. Langmuir 2017, 33, (46), 13295.

6. G. A. Ravi, et al. Materials & Design 2013, 47, 731.

7. C. Qiu, et al. Journal of Alloys and Compounds 2015, 629, 351.

Time

Tue 24 Apr 18
11:00

Organizer

DTU Fysik

Where

DTU Lyngby Campus
Building 311
Lounge/1st floor

 


http://www.fysik.dtu.dk/english/about-dtu-physics/calendar/Arrangement?id=5f97cf38-3faf-416f-8908-9ce889f9f3db
22 JULY 2018