Early Career Researchers – Rising Stars in Nanotechnology forging new paths: Yimin Wu

Yimin Wu joined the University of Waterloo in July 2019 as Assistant Professor in the Department of Mechanical and Mechatronics Engineering and WIN welcomed him as a member in August that year. His research focus is advanced microscopy and imaging techniques, thin film and transition metal oxides, and 2D materials for energy. In 2019-2020, Professor Wu authored a seminal paper in one of the field’s top journals – Nature Energy.

Professor Wu’s work on the ‘Artificial Leaf’ directly addresses climate change and the need for affordable energy at the same time by converting carbon dioxide to an organic compound, much like photosynthesis. While other carbon capture and sequestration technology focuses on removing atmospheric CO2 – a major contributor to climate change – this work converts the CO2 into methanol which is an alternative to diesel fuels. Using operando transmission electron microscopy (TEM) and high-resolution X-ray powder diffraction (HRXRD), copper oxide (Cu2 O) nanocrystals were examined for facet-specific active sites capable of binding and reducing CO2 + H2 O when combined with radiationwith a wavelength of 532nm (in the visible-light spectrum). It was found that the (110) sites on Cu2O served to redistribute electron density for CO2 + H2 O adsorption, lowering the energy barrier allowing for complete reduction to methanol. This provides an unprecedented solar-to-fuel efficiency of 10 per cent to any other CO2 -photocatalysis method. This paper demonstrated the first operando multimodal characterization of light matter interaction under an atmospheric environment and opens the door for finding catalytic materials with other active sites that would give a different reaction pathway to produce fuels other than methanol. The results of this paper were featured in The Independent, CBC News, Canadian Press, BNN Bloomberg, Fast Company, and French Science Magazine.

a) TEM image showing Cu2O truncated cube nanoparticle. b) High-resolution SFXM image of the particle shown in a). c) Schematic of how the electron and X-ray beams aligned with the facets of the nanoparticle. d) location of Cu and O atoms in the nanoparticle facets, e) and f) are graphs received using X-ray scanning nanospectroscopy which demonstrate oxidation state changes at the (110) and (100) facets respectively of nanoparticle in the pristine state, with CO2/H2O gas exposure under dark and under illuminated conditions.

Nanotechnology was always a focus for Professor Wu, even during his undergraduate degree in China, where he studied materials science and engineering. From there, he went on to pursue doctoral studies at the University of Oxford in the United Kingdom, focusing on two-dimensional quantum materials, thin film devices, and aberration corrected scanning transmission electron microscopy. After graduation, he was awarded the SinBeRise Postdoctoral Fellowship at the University of California at Berkeley, and the Lawrence Berkeley National Laboratory for one year. He then joined the University of Illinois as Research Assistant Professor and also at the Center for Nanoscale Materials and Joint Center for Energy Storage Research (JCESR), Argonne National Laboratory in Chicago, where he focused on the advanced catalysts and battery research using integrated imaging approaches.

Yimin Wu first learned about the University of Waterloo from his colleague at the University of Oxford who was a UWaterloo alum in Physics. He was attracted to Canada as a nation because of its reputation for inclusivity, and to UWaterloo for its reputation for research excellence and its unique policy on intellectual property. “WIN was the right fit for me, a very inclusive institute and truly interdisciplinary. This allows research to make a difference – you can really attack problems that matter – to directly improve people’s lives.” 

Yimin Wu has been very productive as an early-career researcher since he graduated from Oxford seven years ago; he has already authored and co-authored more than 30 peer-reviewed journal papers and is listed as an inventor on a US/international patent. He has also received 10 awards since graduation – including the MIT Technical Review Innovators Under 35 Award Finalist (2020). We look forward to what the next seven years will bring!