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Meet our young scientists - Dr Junzhi LIU

Meet our young scientists - Dr Junzhi LIU

Portriat of Dr Jinyao TANG

Dr Junzhi LIU

Assistant Professor of Department of Chemistry

  • 2021 NSFC Excellent Young Scientists Fund (Hong Kong & Macau)
  • 2020 Early Career Award, Research Grants Council
  • 2020 Selected for the Early Career Advisory Board for Chemistry - An Asian Journal

 

Topological Molecular Nanocarbons Laboratory

Q: What do you think are your most significant research accomplishments, and what has been the impact of your research?

A: Until now, the major academic contribution from my side is implementing the nonalternant topologies, especially the pentagonal and heptagonal rings (azulene units), into graphene nanostructures at the atomic and molecular level (Figure 1), which is now an extremely hot topic but was indeed initiated by my group. For example, we demonstrated the first example of open-shell nanographene containing two azulene units, in which the spin densities are localised on the edges of heptagonal rings, and the first synthesis of three unprecedented anti-aromatic nanographenes with seven-five-seven-membered rings (Figure 1). The synthetic strategy regarding the nonalternant topologies in nanographenes by building azulene units can be applied to the construction of other air-stable and π-expanded molecules and polymers with anti-aromatic/open-shell structures. Apart from the aromatic polycyclic hydrocarbons, we created a completely new topic of π-conjugated ‘Molecular Transformer’, which is very attractive from a materials point of view, but quite challenging. This developed molecular transformer can be used as an adaptable host, providing excellent opportunities for application in the field of host-guest supramolecular chemistry.

Figure 1. Representative research results from Dr Liu’s group.

Figure 1. Representative research results from Dr Liu’s group.

 

Q: Please give a brief description of 1 - 2 ongoing research projects that best reflect your visions in the scientific field.

A:  Molecular topology is an important feature of most polycyclic arenes, which closely couples with their optical and electronic properties. Carbon allotropes, including 0D fullerene, 1D carbon nanotube and 2D graphene, composed entirely of sp2-hybridized carbons are the most well-investigated class nowadays. Instead of these well-developed 1D and 2D nanocarbons, I always ask myself how we can go beyond the current state of the art. Such as, can we develop an atomically precise synthesis of 3D carbon nanostructures through the bottom-up organic synthesis, such as Mackay crystal and/or cubic graphene? At this moment, my research group is working hard to develop the related synthetic approaches and resolve the challenges in this field. Hopefully, we can achieve good progress in the next 2 - 3 years.

 

Q: What is the most important question you want to address?

A: As we know, graphene, a 2D allotrope of sp2-hybridized carbons, has exotic low-dimensional physical properties that could be developed into revolutionary contemporary electronic devices, which has already been recognised by the 2010 Nobel prize. From a chemist's point of view, perfect graphene also can be regarded as fused benzenes with sole six-membered rings. In my research group, we give great contribution on introducing the pentagonal and heptagonal rings into nanocarbons. Therefore, compared to the 2D graphene, we are considering whether we can fabricate an atomically precise synthesis of pentaheptite (Figure 2), which is a 2D sheet only containing five- and seven-membered rings. Once this pentaheptite is successfully achieved, it would definitely be a breakthrough in 2D materials no less than the discovery of graphene.

Figure 2. The structures of graphene and pentaheptite.

Figure 2. The structures of graphene and pentaheptite.

 

Q: Where do you see yourself in five years/ ten years? What do you want to accomplish the most?

A: I hope, personally, to reach a certain place where I can distinguish myself from the numerous researchers who have worked and am currently working with in the field of aromatics. This requires absolute innovation and the establishment of a unique research label. This way, when people mention this field, they know who did it or who did it best. Towards this end, we not only need to pioneer the new field, but also need to lead the field of our research. Thus, I expect that I can become a top key player in the field of nonalternant topology and 3D nanocarbons in the next five years. As mentioned before, right now, I am most interested in pentaheptite nanocarbons with only pentagonal and heptagonal rings. In the future, I hope that my team can accomplish the atomically precise fabrication of pentaheptite through the bottom-up method in the next 5 - 10 years, which will bring forth a new era for 2D and carbon materials. For sure, there is no doubt that we need to work very hard towards this goal.

 

Q: What are the challenges you are facing?

A: My research interests focus on the design and synthesis of novel aromatic molecules. In addition to methodology and structure-oriented issues, the biggest challenge is how to identify the applications for these new molecules. In my opinion, the most promising applications of our molecules lie in their molecular structures that can be used in creating advanced organic materials with tailored properties, including organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs), organic photovoltaic (OPV) solar cells, spintronics, etc. This requires joint efforts from different areas. Moreover, as a young scientist at the beginning of their independent research career, another big challenge for me is how to acquire enough funding to conduct fundamental research. Currently, in many countries/areas, funding agencies would like to put more resources to translational research hence there is very narrow scope for fundamental research nowadays. Here, I significantly appreciate the funding support thus far from our department, HKU and Hong Kong.

 

Q: Who has influenced you the most?

A: Many seniors have profoundly influenced my research career. In particular, my Ph.D. supervisor, Professor Klaus MÜLLEN from Max Planck Institute for Polymer Research (Germany), has very strongly influenced my academic career as he provided me with rigorous Ph.D. training and led me into the world of synthetic chemistry. My postdoctoral mentor Professor Xinliang FENG from Technische Universität Dresden (Germany) taught me a lot, from every detail of how to do research to how to be a responsible and trustable person. The attitudes of both towards science continues to encourage and inspire me during my independent research career. Here, I would also like to express my special thanks to Professor Chi Ming CHE, Head of Chemistry, who has provided me great guidance and help since the start of my independent career at HKU.

 

Q: How would you go about motivating yourself when you are going through a low point?

A: Actually, there was a low point during my Ph.D. study, my research work was not going well for a while. I told myself three words: persistence, persistence, and persistence! During that time, I remember very clearly that I listened to the same song repeatedly, Invisible Wings from Angela Chang, which gave me a sense of peace. I like the lyrics in it: ‘I know I always have a pair of invisible wings, that will make me fly and give me hope. I finally see all my dreams come true’. Even right now, I still like this song and listen to it frequently.

 

Q: Can you tell us more about your research group? What are the roles and the missions? 

A: My research group at HKU begun in August 2019 and quickly grew into a strong multidisciplinary research team, comprising of 2 postdocs, 1 research assistant and 8 PhD students. Currently, my research group focuses on the field of atomically precise synthesis of nonalternant topologies in graphene nanostructures, including 0D nanographenes, 1D polymers and 2D nanosheets (such as pentaheptite nanocarbons), to provide a route for accessing novel properties such as curvatures, open-shell characters, and new electronic functionalities for applications in organic devices. Beyond the 1D and 2D nanocarbons, we also focus on the atomically precise synthesis of 3D topological molecular carbons. In addition to the basic research, we try to bridge the gap between the fundamental framework and its practical applications and promote the transformation of laboratory research results into realistic productivity, serving the economic and social development of Hong Kong, the Greater Bay Area and Mainland China.