New material is developed that can reduct environmental hazardous substances and carbon dioxide using only natural sunlight.

Professor Kim Young-hoon's research team of the Department of Energy Engineering at Hanyang University recently developed photocatalytic materials for carbon dioxide reduction and wastewater decomposition using solar power to prepare for global warming and climate change. The technology is expected to be used as a photocatalyst material to prepare for a carbon-neutral society in the future as it can reduce organic matter in wastewater and carbon dioxide in atmosphere by using only sunlight in absence of external devices.

Photocatalyst is a semiconductor that decomposes a material adsorbed on a surface through oxidation or reduction using electrons and holes excited by absorbing light like a catalyst and is known as an eco-friendly treatment method. However, recently commercialized photocatalytic materials include titanium oxide and zinc oxide, and these semiconductor materials have so wide band-gap that they can only utilize ultraviolet areas that are less than 5% of the sunlight. Therefore, an external device that generates ultraviolet rays is essential to implement a photocatalyst using such a semiconductor, which results in a problem of incurring additional costs for maintenance.

To solve this problem, the researchers developed a perovskite/titanium oxide heterostructure complex photocatalyst by applying halide perovskite material, that can utilize visible light areas that make up most of the sunlight, to titanium oxide. In the synthesized complex, perovskite material absorbs sunlight, and excited electrons move to titanium oxide, enabling carbon dioxide reduction and decomposition of waste organic matter using visible light, which was previously impossible. Using only natural sunlight without external devices, the CO2 reduction efficiency of 12.77 mmol g-1h-1 level seen by existing titanium oxide was improved to 30.43 mmol g-1h-1, showing the possibility of a next-generation photocatalyst material for carbon neutrality in the future.

This study is supported by the Hanyang University Joint Research Team Support Project, National Research Foundation of Korea’s Support Project for Leading Research Center, and Ministry of Trade, Industry and Energy’s Industrial Technology Alchemist Project. Kim Young-hoon, a professor at the Department of Energy Engineering at Hanyang University participated as the corresponding author, and Kim Tae-hyung, a student in Ph.D. course in the Department of Energy Engineering at Hanyang University participated as the lead author of the study, and published the study on January 31 in the international journal, "Nanoscale” (Impacting factor: 8.307).

(from the left) Professor Kim Young-hoon and Kim Tae-hyung, student in Ph.D. course, of the Department of Eenrgey Engineering.

Evaluation of hotocatalytic property using natural sunlight.

A schematic diagram of phocatlytic synthesis of heterostructures.