Electric lines, cooking gas, petrol engines, pocket batteries; most of us may find it hard to imagine daily life in a world without these. But as we grapple with the challenges of climate change and environmental degradation, the technologies we use to generate, store, transform and utilise energy are a key force in shaping a sustainable future.
A*STAR National Science Scholar (PhD) recipients Rebecca Khoo and Kang Rui Garrick Lim are among many researchers working on cutting-edge materials with an eye on sustainability. Intrigued by the chemistry that binds together the stuff of our world, Khoo and Lim are exploring different facets of materials science that support solutions ranging from improved carbon capture to efficient chemical manufacturing.
In this interview with A*STAR Research, Khoo and Lim reflect on their journeys with A*STAR, share details about the projects they’ve enjoyed working on, and give their advice for those beginning their careers in science.
1. What led you to your current research?
RK: I became interested in materials science and chemistry during my pre-university internship in Singapore General Hospital’s Orthopaedic Department, where I learned about research in biocompatible materials for joint replacement implants. This led me to pursue a chemistry degree at the National University of Singapore (NUS), where I had the chance to explore topics ranging from superhydrophobic surfaces to catalysts.
After graduation, I joined A*STAR’s Institute of Materials Research and Engineering (IMRE) and had a good time working on utilising carbon dioxide (CO2) to make novel polymers and supramolecules. From there, I applied for the NSS (PhD) to expand my horizons at the frontiers of gas capture, separation, storage and catalysis technology at the University of California, Berkeley, US.
GL: My first exposure to A*STAR was as an upper secondary school student, when I was selected for the A*STAR Science Award. I remember taking a tour of IMRE in 2009; it was my first glimpse into what a research laboratory looks like.
Since then, A*STAR has supported me throughout my eventful 15-year journey; one that spanned my undergraduate education at NUS and three research stints at IMRE. I came to realise that pursuing a career in scientific research would allow me to continue tinkering with materials and deliver real-world impact by increasing human knowledge and experience. I wanted to create that impact in Singapore, which was why I applied for the NSS (PhD).
2. What are some interesting projects you’ve worked on?
RK: For my PhD, I studied metal-organic frameworks (MOFs): these are a highly versatile class of porous, crystalline solids built from molecular building blocks. Putting them together is not unlike stacking Lego bricks.
MOFs fascinate me by simply blending different atomic components, these frameworks can be customised for various uses, such as greenhouse gas capture and storage; separation and purification of gaseous mixtures; and solid-state catalysis for both liquid and gas-phase chemical reactions.
At the Institute of Sustainability for Chemicals, Energy and Environment (ISCE2), my research is currently focused on the mechanochemical degradation and alteration of polystyrene, which aims to enable this typically non-recyclable plastic to be recycled and repurposed. Mechanochemistry is a straightforward and environmentally-friendly approach because it uses physical forces, such as impact and shear, to trigger reactions without a lot of harmful solvents and complicated processes.
GL: As a fourth-year chemistry PhD student at Harvard University, US, I’m working on developing new methods to prepare catalysts, which help achieve more energy-efficient chemical transformations. Catalysts drive practically all industrial chemical production, and there’s an urgent need to develop more efficient, selective and durable catalysts.
My research at Harvard specifically taps on colloidal chemistry as a toolbox to create a catalyst platform with multiple components and features that can be independently swapped out if needed. Such a model catalyst platform would enable researchers to isolate and investigate the independent effects of any of the catalyst’s features—chemical or physical—on its resulting catalytic performance.
The project has been the subject of a Harvard press release; I’m happy that our team’s efforts are gaining international attention. The catalyst platform we developed was inspired by the nanostructure of butterfly wings, and we continue to look for inspiration all around us.
3. How does your work support sustainable energy research?
RK: In one of my current projects, I design and synthesise new MOFs for CO2 utilisation and small molecule catalysis. MOFs show great potential as sorbents for carbon capture and storage; they can essentially soak up CO2 like a sponge. If that potential is realised, that functionality could propel many international initiatives that aim to scale up and industrialise MOFs. I hope to play a part in advancing this field and contribute to Singapore’s efforts towards achieving net-zero emissions.
GL: Before my PhD, I spent a year at IMRE developing electrocatalysts for hydrogen evolution. Prior to that, my research at NUS involved synthesising nanomaterials that could capture sunlight to be harvested as light energy. Energy capture, storage and conversion have been recurring themes in my research journey. I hope to see more young students and researchers joining us on this ride, because this endeavour is going to need all of us.
4. What excites you about your journey ahead?
RK: The present is an exciting time not just for myself, but for everyone dedicated to sustainability research. People are beginning to recognise the need for, and the significance of, sustainable practices. I hope to play my part in addressing global energy challenges and contribute to securing a viable future for generations to come.
GL: My work has brought me to different parts of the world and allowed me to engage with other researchers. I hope to continue to learn from some of the brightest minds here at Harvard during my PhD, and beyond.
Being young also grants me ample energy to experiment boldly at the laboratory bench! My PhD advisor is deeply intrigued by all things science, and I hope to bring that same infectious enthusiasm into my research.
5. What advice would you give young STEM graduates?
RK: Always prioritise your mental and physical well-being, and do allocate time for family, friends and leisure! Remember that failure is not the end, but rather a learning opportunity for growth.
Embrace the opportunity to ask questions—regardless of how trivial they may seem—as they will give you valuable insights. Also, be open to sharing your thoughts and opinions with supervisors, mentors and peers; you never know when it might spark innovative breakthroughs.
GL: I hope that aspiring researchers, myself included, will fondly remember what brought them to science in the first place. I learned early that scientific research is fraught with failure and rejections. The first advice my PhD advisor gave me is that science is non-linear: some days you will have much to discuss, and on other days, nothing much. Knowledge creation is difficult, and translating that knowledge into something tangible that benefits many others only compounds that challenge even further.
My hope is that students will bring cautious optimism and their unique perspective into their scientific research; work on problems that keep them up at night; and persevere when things do not go as expected. Behind every “aha!” landmark experiment lies months and years of hard work. I hope that our budding scientists will find their own eureka moment(s) in time to come.
