Although fossil fuels—coal, oil and natural gas—have helped to build our modern world, the emissions they produce stand as the greatest driver of the ongoing climate crisis, while the plastics they make linger in our soils and oceans. These problems have spurred researchers worldwide to accelerate our shift towards cleaner energy and greener materials.
“Whether it’s upcycling recalcitrant plastics, designing recyclable batteries or finding new uses for waste CO2, the possibilities of sustainable chemistry are endless,” said Celine Yeung, an A*STAR National Science Scholar previously based at A*STAR’s Institute of Materials Science and Engineering (IMRE).
Like plants, scientists like Yeung are turning to the sun for inspiration. A significant power source, solar energy already generates over five percent of the world’s electricity today. However, unlike oil or coal, it remains challenging to store solar energy or convert it into industrial materials at a vast scale.
Drawing inspiration from photosynthesis—the process through which plants turn sunlight into food—Yeung is one of many researchers working on ‘artificial leaf’ devices that combine light absorbers and catalysts to convert water and waste carbon dioxide into sustainable fuels. While much work remains to optimise their efficiency and ensure they’re made from eco-friendly materials, these devices may bring us closer to a solar-powered world.
In this interview with A*STAR Research, Yeung looks back on her enduring fascination with science, shares her deep passion for sustainable chemistry, and offers valuable advice for aspiring STEM graduates.
Why does sustainable chemistry matter to you?
Sustainability is a complex, multifaceted topic that needs collaboration and input from various stakeholders. To me, sustainable chemistry is a subset of this overarching goal, where scientists leverage the tools of chemistry to design and manufacture new systems that reduce our ecological footprint.
Quoting the United Nations’ 1987 Brundtland Report, we aim to “meet the needs of the present without compromising the ability of future generations to meet their own needs”. This implies moving beyond bench-scale processes to develop industrial systems that are not only economically viable, but relevant to wider communities. The inextricable link between sustainable chemistry and our daily lives makes it a worthwhile endeavour to pursue.
Tell us about your scientific journey.
My interest in science began early; I spent school holidays joining science workshops at local community centres and signing up for mini-research projects in high school. I have fond memories of making ice cream and baking soda volcanoes, cultivating hydroponic kangkong plants (our mums whipped up tasty dishes afterwards!) and growing copper sulfate crystals with my project buddies.
With the A*STAR Undergraduate Scholarship, I pursued chemical engineering at the National University of Singapore (NUS). While there, I refined my research skills by taking on various projects with domain experts from IMRE, A*STAR’s Singapore Institute of Manufacturing Technology (SIMTech) and NUS itself.
After graduation, it was natural to continue with the A*STAR National Science Scholarship (PhD). For my one-year research attachment, I returned to IMRE’s Soft Materials Department; I’d previously spent a great summer interning with Shermin Goh, and this time I got to work at a fume hood adjacent to her, under Jason Lim in the Sustainable Supramolecular Materials Group.
On reflection, I’m grateful to all the inspiring teachers, scientists and professors I’ve met along the way who encouraged me to follow my dreams and passion for science. What makes scientific research exciting is that there isn’t one fixed correct answer, and no two projects are identical; each has its own unique challenges and creative solutions.
Why should we transform plastic waste into functional materials?
During my time at IMRE, we focused on developing different strategies to chemically upcycle waste plastics. Tapping into these underexplored resources—rather than sending them to landfills or incineration plants—can reduce our carbon footprint. If we continue our current levels of waste generation, Singapore’s only landfill, Pulau Semakau, is expected to be fully filled by 2035.
One issue is that non-biodegradable plastics, such as polyolefins, have strong C–C and C–H bonds that can’t be easily broken down by chemicals or enzymes. Our research at IMRE has shown a viable solution: we can transform these waste plastics into functional materials such as anti-fungal polymers and catalysts for biomass conversion, thereby giving them a new lease of life.
Tell us about your current work.
In the autumn of 2021, I joined Erwin Reisner’s group at the University of Cambridge’s Chemistry Department for my PhD studies. Despite being half the globe away from my sunny island home, I am exploring a topic close to my heart: solar energy.
Inspired by nature, my work revolves around developing photoelectrochemical devices to produce solar fuels. These devices mimic photosynthesis by coupling synthetic light absorbers with suitable catalysts to directly harness, convert and store solar energy in the form of chemical fuels—all using water or waste CO2 as starting materials. Those fuels can then be transported and used on demand to power fuel cell electric vehicles, like hydrogen-based ones, or produce commodity chemicals.
From solar panels on the rooftops of HDB flats to floating solar farms on the Tengeh Reservoir, there is an immense future potential for solar energy research in Singapore. My goal is to transition us away from existing precious metal or lead-based prototype devices and, through rational design, create high-performing standalone systems fully powered by sunlight.
What excites you about your journey ahead?
Singapore’s dynamic, progressive and ever-changing research landscape. That vibrant ecosystem is essential for exploring new ideas and forming collaborations. A*STAR also provides a good platform for conducting interdisciplinary work as it oversees a diverse talent pool that spans 17 different research institutes.
Speaking with friends of various nationalities, I realized how fortunate we are to have extensive funding for R&D, with A*STAR and local universities housing state-of-the-art equipment for cutting-edge research. In the near future, I hope to apply the skills I’ve learnt abroad to the Singaporean context and contribute in unique ways.
Beyond research, I believe it’s also important to pay it forward and mentor the next generation of budding scientists during my deployment. The A*STAR scholarships allowed me to pursue world-class education both locally and abroad without financial worries, providing opportunities to work under scientists with different mentoring styles. From revising my first manuscript to tagging along for departmental seminars, these experiences have shaped my scientific perspective and prepared me well to embark on a PhD degree.
What advice would you give those pursuing similar STEM journeys?
I would like to share a quote by the late Stephen Hawking, a British physicist and cosmologist: “Science is not only a disciple of reason but, also, one of romance and passion.” Research is indeed an arduous but rewarding journey because you are stepping into the unknown, constantly adapting and always learning something new.
I had a tough start to my PhD, given that it was my first foray into optoelectronics and electrochemistry; I spent countless nights troubleshooting in the lab. I do remember my excitement when I finally made my first working device—I immediately fabricated at least three more copies to assure myself that I wasn’t dreaming!
It’s always the darkest before dawn, but find the burning passion within yourself to stay motivated even when you’re at your lowest. Along the way, do reach out and seek support from your principal investigator and lab mates; their fresh perspectives will help you grow and mature as a scientist.
