Microplastics from Sunlight and Electricity → Converted into Chemical Fuels

Research Team Led by Professor Park Chan-beom at KAIST

Establishing Microplastic Upcycling Using Sunlight and Electricity. Cover Article of Nature Synthesis October Issue

[Asia Economy Reporter Kim Bong-su] Domestic researchers have developed a technology that converts microplastics dissolved in seawater into various high value-added compounds using sunlight and electricity.

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 17th that Professor Park Chan-beom's research team from the Department of Materials Science and Engineering, in collaboration with Professor Frank Holman’s team at TU Delft in the Netherlands, succeeded in converting microplastics into chemical fuels using sunlight and electrical energy, and combining microplastic upcycling with biocatalytic reactions to produce various high value-added compounds. The results of this study were published as the cover paper in the October issue of the international journal 'Nature Synthesis'.

Plastic is an essential material in modern life, with approximately 390 million tons produced worldwide annually. Recently, due to the coronavirus pandemic, the demand for plastics has increased further because of the increased use of packaging materials and personal protective equipment. Most plastic waste is treated by incineration or landfill in the natural environment, causing environmental and economic problems. In particular, microplastics generated during this process accumulate in living organisms, posing an ecological threat.

The research team developed a photoelectrochemical method to upcycle microplastics using solar energy and electrical energy. Using hematite, which is widely found in nature, as a photocatalyst, they converted polyethylene terephthalate (PET) microplastics into chemical fuels such as formate and acetate. Through spectroscopic and (photo)electrochemical analyses, they revealed the scientific principle that the photoexcited hole of hematite is key to the upcycling reaction. They also demonstrated that the same recycling reaction occurred with plastic containers from Starbucks and Coca-Cola, establishing the practical applicability of the system.

Additionally, the research team combined the plastic upcycling photocatalytic reaction with various biocatalytic reactions. Existing photoelectrochemical systems that activate redox enzymes relied on the water oxidation reaction. However, this posed problems such as slow reaction speed and the production of oxygen, which has low economic value. By utilizing the fact that the plastic upcycling reaction is faster than the water oxidation reaction, the team not only accelerated the redox enzyme reactions but also succeeded in simultaneously producing high value-added compounds (chiral compounds, pharmaceutical intermediates, chemical fuels, etc.) at both the anode and cathode.

Professor Park said, "This study is significant in that it proposed a photoelectrochemical method for sustainable solar-chemical energy conversion while addressing environmental issues," adding, "We plan to develop photocatalysts that can upcycle microplastics faster and find ways to upcycle various types of plastics."

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