Hydrogen Produced from Waste Plastics? – Novel Material Development through Plastic Photo-upcycling
A conversion of 98% was accomplished in a hydrogen production reaction from waste PET plastic bottles. 
The research results were published in Nature Materials.

▲ (From left) Distinguished Professor Hyeon Taeghwan (corresponding author, Center for Nanoparticle Research, Institute for Basic Science (IBS); and School of Chemical and Biological Engineering, Seoul National University), 

Professor Lee Byoung-Hoon (corresponding author, KU-KIST Graduate School of Converging Science and Technology), and Lee Chan Woo (first author, Center for Nanoparticle Research, IBS).

Professor Lee Byoung-Hoon of the KU-KIST Graduate School of Converging Science and Technology conducted a joint study, with Professor Hyeon Taeghwan, the head of the Center for Nanoparticle Research of the Institute for Basic Science (IBS) and Professor Kim Minho of the Department of Applied Chemistry of Kyung Hee University, to develop a catalyst for converting waste polyethylene terephthalate (PET) plastic bottles into eco-friendly hydrogen using sunlight.

Over five billion PET plastic bottles are consumed by Koreans each year. However, due to the high cost of recycling waste PET plastic bottles, their recycling rate is less than 50%, and the bottles are discharged as waste plastics, causing environmental pollution. The joint research team was able to convert 98% of PET plastics into hydrogen by subjecting them to a reaction producing hydrogen by photo-reforming waste PET bottles using an optimized catalyst. In addition, they were able to achieve the highest reaction efficiency of 3.7 L of hydrogen per hour while consuming 1 g of catalyst.

The research results were published on line on February 6 in Nature Materials (IF: 47:66), a globally renowned journal.

* Article title : Photochemical tuning of dynamic defects for high-performance atomically dispersed catalysts

This technology is particularly valuable because it provides an eco-friendly and low-cost way of producing atomic dispersion catalysts, a key catalytic system that can significantly reduce chemical industry costs. Unlike existing synthetic processes, this approach to catalyst production is possible using only solar energy and without any applied heat energy. In addition, the technology is a general-purpose technology that can be applied to other metal atoms (platinum, iridium, copper) and oxides (titanium dioxide (TiO2), zinc oxide (ZnO), cerium oxide (CeO2)) that are important in catalytic reactions.

Conventional nanoparticle-based catalyst systems have the disadvantage of being hardly applicable on an industrial scale due to the issues of economic feasibility that arise when expensive precious metals are used. Furthermore, in the case of nanoparticle systems, because the effect of metal-metal interaction dominates, the metal-support interactions that can exhibit new catalytic reaction behavior and performance are less likely.

To overcome this disadvantage, the IBS research team used light energy to intentionally move the oxygen defects existing inside commercially available oxide materials to the surface, and utilized the oxygen bonding sites exposed on the surface as bonding sites for single atoms. This synthetic method has the advantage of being applicable to various types of metal atoms and metal oxides. In particular, by using the bonding of Pt atoms of specific electronic structure and TiO2, the researchers were able to achieve a 98% hydrogen conversion rate from waste PET plastic bottles, which is the world’s highest efficiency.

Professor Lee Byoung-Hoon of the KU-KIST Graduate School of Converging Science and Technology said, “Since our technology can be used to prepare various high-performance atomically dispersed catalysts, we will apply the catalysts synthesized using our synthetic method to varied reactions of industrial significance.”

Lee Chan Woo, the first co-author from the IBS Center for Nanoparticle Research, explained, “The new synthetic method that we have developed can be applied to various high-performance atomically dispersed catalysts in an eco-friendly manner using the unlimited solar energy available.”

Professor Hyeon Taeghwan, the head of the IBS Center for Nanoparticle Research, commented, “The only type of energy required by the synthesis process is solar energy. As our technology allows for quick and easy synthesis, we can anticipate the expansion of its application to an industrial scale.”

<Figure 1>

▲ [Figure 1] A schematic diagram of the synthesis method developed by the research team, and an electronic microscope image of the synthesized catalyst.

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▲ [Figure 2] The photocatalytic performance of the catalyst developed by the research team.