On 21 September 2017 Yu Xu successfully defended his thesis “Continuous Hydrothermal Flow Synthesis of Functional Oxide Nanomaterials Used in Energy Conversion Devices” on synthesis of nanoparticles and nanomaterials for energy conversion devices such as solid oxide fuel cells, electrolysis cells and batteries.
Just like you need the right mix of cement, gravel and bricks when building a house, you need the right mix of initial building blocks when researching in materials for energy conversion. Except that with houses, you have centuries of trial and error on what works and what doesn’t, while energy materials for batteries, solid oxide fuel cells (SOFC) and electrolysis cells (SOEC) are still a work very much in progress.
In his PhD study Yu Xu investigated how to synthesize the right amounts and the best possible compositions of nanoparticles and nanomaterials for energy conversion. Just like a molecular cook, Yu Xu adds a drop of this, two drops of that and just a pinch of something else to mix and form the exact right material, except his equipment is rather more advanced than you will find in a typical kitchen.
“I work on the nanoscale, using high-tech microscopes and different synthesis techniques like hydrothermal flow and high pressure synthesis to identify, to manipulate and to create the exact right materials for energy conversion”, says Yu Xu. During his PhD at DTU Energy, Yu Xu took part in creating a scalable prototype flow reactor for synthesizing materials for functional oxide materials, in particular anodes, cathodes and electrolytes for SOFC and SOEC.
"I work on the nanoscale, using high-tech microscopes and different synthesis techniques like hydrothermal flow and high pressure synthesis to identify, to manipulate and to create the exact right materials for energy conversion"
Postdoc Yu Xu, DTU Energy, while defending his PhD
“Very often, when creating anodes, cathodes and electrolytes, you can buy the powders and the materials you need at the commercial market, but maybe they don’t have the very exact specifics, that you want. We are able to control the parameters, using our flow reactor and DTU Energy’s vast knowledge of modelling, morphology and viscosity to design, shape and refine the materials into what is needed”, Yu Xu explains.
The prototype flow reactor has five inlets and can mix the materials in a variety of previously known and also new ways. “The goal was to prove the versatility of our prototype reactor. It proved surprisingly easy to make several types of materials for anodes and electrolyte, while it was relatively tough finding the right technique for a cathode, but we did it using groundbreaking techniques, and that was very interesting to be part of”, says Yu Xu, who has really appreciated his stay as a PhD student at DTU Energy.
“I hadn’t been outside of China when I arrived three years ago, so arriving at Denmark was a culture shock at many levels, but I have grown a lot being here. I am a very different me than I was three years ago and I attribute this largely to my good supervisors and colleagues, as I have learned quite a lot. It was good.”
Having defended his thesis successfully, Yu Xu is now a postdoc at DTU Energy for the next six months.