Professor Jihun Oh’s research team in the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) has developed a new nanoporous gold thin film and silicon-based photoelectrode used in the photoelectrochemical (PEC) reduction of carbon dioxide. A recent global hot topic, PEC reduction decreases carbon dioxide levels in the air by transmuting carbon dioxide and water into fuel using solar energy.

For a stable rate of carbon dioxide reduction, an excelling low overvoltage catalyst is necessary. While gold is an electrocatalyst able to reduce carbon dioxide to carbon monoxide, gold has a comparably higher overvoltage along with several other disadvantages including price and the hydrogen being produced. To address these problems, the research team succeeded in creating a nanoporous gold thin film. This film was then attached onto the printed circuit board material of the photoelectrode and was anodized, which allowed the gold film to continue to reduce carbon dioxide continuously. To utilize this new thin film, the research team further developed a silicon photoelectrode.

Overall, the new photoelectrode yielded an extraordinarily high efficiency in carbon dioxide reduction into carbon monoxide. Previous catalysts were produced into 0.1 mm films. In contrast, the new gold thin film was 200 nm thick, being about 50,000 times thinner. Furthermore, the gold thin film alone produced a 96% Faradaic efficiency, the efficiency at which electrons are transferred in a system, at 480 mA of overpotential. When meshed with the photoelectrode, it exhibited a 91% Faradaic efficiency. The research team hopes that its results will become the structural basis of semiconductor photoelectrodes. “The photoelectrode will serve as a good platform for applications for several semiconductors and catalysts,” said Professor Oh. He also added, “other researchers will be able to improve the efficiency of carbon dioxide PEC reduction using our team’s structure.” The research results were published in Advanced Energy Materials on February 8.

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