Kitchen Essential Transforms into Hydrogen Production Catalyst?... The Twist of the "Frying Pan Coating Agent"

A technology has been developed that increases the production performance of green hydrogen devices by 1.4 times by applying a frying pan coating agent to their components.

The principle is that the coating agent prevents hydrogen bubbles from adhering, allowing the produced hydrogen to be smoothly released.

The team led by Professors Dongwook Lee and Jungki Ryu from the Department of Energy and Chemical Engineering at UNIST announced on November 24 that they increased hydrogen production performance by 40% by coating the porous transport layer (PTL), a key component of water electrolysis devices, with Teflon (PTFE).

Research team, (from left) Professor Dongwook Lee, Professor Jungki Ryu, Researcher Yunseok Kang (first author), Researcher Seunghyun Lee (first author). Provided by UNIST

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A water electrolysis device produces green hydrogen using water and electricity. Hydrogen is generated through chemical reactions on the catalyst surface of the device’s electrodes. If hydrogen gas does not escape in time and covers the catalyst surface as bubbles, it blocks the reaction, causing problems. This is because the effective catalyst surface area for the production reaction is reduced.

The research team solved this problem by applying Teflon to the electrode’s porous transport layer, which serves as the passage for hydrogen gas to escape. Teflon is a material commonly used as a coating to prevent food from sticking to frying pans. When this material is coated onto the transport layer, hydrogen can quickly pass through the porous structure and be released, preventing bubbles from adhering to the catalyst surface.

Additionally, to avoid blocking the supply of raw materials, the team did not coat the lower half of the transport layer. The transport layer serves both as the passage for hydrogen, the product, to escape and as the channel for supplying water, the raw material, to the catalyst. Since this coating agent repels water, by coating only the upper half of the transport layer, the lighter hydrogen gas can flow out through the coated upper section, while the raw material water can still be supplied efficiently through the lower section.

When this coated porous transport layer was applied to a water electrolysis cell, the current density increased by 40% compared to a cell without the coating. Current density is an indicator proportional to the production amount per unit time. Moreover, the voltage rise caused by hydrogen gas blocking the passage was also alleviated.

The coating process is simple, making commercialization advantageous. The process only requires spraying the liquid coating agent and heat treatment, without any separate nano-fabrication or complex procedures. The research team also successfully produced a large-area transport layer with an area of 225 cm².

Professor Jungki Ryu stated, "In water electrolysis, it has been known that the more hydrophilic the porous transport layer is, the more efficiently water, the raw material, is supplied, leading to higher efficiency. However, we confirmed that hydrogen production can actually be improved by effectively utilizing a hydrophobic coating agent."

Professor Dongwook Lee added, "Since Teflon is already a widely used material, it is easy to handle, and this method only requires adding a coating to the surface while keeping the existing water electrolysis device structure unchanged, making it easy to apply. This technology could also be applied to other electrochemical devices where gases are involved in chemical reactions, such as fuel cells or metal-air batteries."

Structure of the electrode in the existing hydrogen production system (left) and the electrode with a coated layer applied (right).

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This research was led by researchers Yunseok Kang and Seunghyun Lee from the Department of Energy and Chemical Engineering at UNIST.

The research results were published online on November 8 in Advanced Science, a leading international journal in the field of electrochemistry, and have been selected as a cover paper, with formal publication forthcoming.

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