High-Efficiency Process Simultaneously Produces Hydrogen and High-Value Silica From废Solar Silicon · Silica Film Removal Pushes Hydrogen Yield to Near Theoretical Limit Let me restart cleanly. —
As first-generation solar panels reach the end of their lifespan and waste panels pile up, researchers have developed a technology that can simultaneously produce high-purity hydrogen and high-value chemical materials from the silicon in discarded solar panels. The technology is drawing attention as an economically viable and environmentally friendly solution for disposing of waste solar panels, which are difficult to landfill due to secondary pollution concerns and hard to incinerate even at high temperatures.
A research team led by Professor Baek Jong-beom in the Department of Energy and Chemical Engineering at the Ulsan National Institute of Science and Technology (UNIST) announced on Wednesday that it has developed a high-efficiency process that uses silicon from waste solar panels to simultaneously produce high-purity hydrogen and silica, a high-value industrial material.
Silicon can react with water to produce hydrogen and silica. In practice, however, a silica film that forms on the silicon surface as soon as the reaction begins blocks water from reaching the silicon, halting the reaction. This has kept hydrogen output far below the theoretical maximum.
The research team developed a process that removes this silica film without using harsh chemicals, producing up to five times more high-purity hydrogen than conventional methods. The principle works by placing silicon and water in a container filled with small beads and rotating it. The beads and silicon particles collide with each other, repeatedly breaking and stripping away the silica protective layer.
Experiments showed that approximately 1,706 mL of hydrogen was produced per gram of commercial silicon. This represents 99.6% of the theoretical maximum output of 1,713 mL g⁻¹. Compared with conventional thermochemical methods, which typically achieve only about 18% to 28% of the theoretical maximum, the new process delivers up to five times higher hydrogen production efficiency.
In a separate experiment using silicon powder obtained directly from waste solar panels, hydrogen production performance reached approximately 98% of the theoretical maximum.
The silica produced as a co-product also demonstrated excellent performance as a catalyst support. A catalyst support is a material that evenly disperses and anchors the active metal particles of a catalyst. A nickel catalyst using the produced silica recorded higher carbon dioxide conversion rates and methane selectivity in a chemical reaction converting carbon dioxide into methane than a catalyst using commercial silica. The superior performance was attributed to the abundance of hydroxyl groups (-OH) on the silica surface, which better disperse catalyst particles.
In terms of economic viability, even excluding any revenue from the silica byproduct, the hydrogen production cost of this process was found to be tens to thousands of times cheaper than conventional thermochemical methods. When silica sales revenue is factored in, a "negative cost structure" in which producing hydrogen actually generates profit becomes possible, according to the analysis. The continuous processing method also showed far superior output and energy efficiency compared with batch processing, making it well-suited for immediate deployment at large-scale industrial sites.
"The strength of this technology lies in its ability to produce hydrogen in an environmentally friendly way using silicon from waste solar panels while also obtaining industrially useful silica," Professor Baek said. "It will greatly contribute to building a circular resource economy by transforming troublesome waste solar panels into high-value resources."
The research findings were published online on March 27 in Joule, one of the most prestigious journals in the energy field. The mechanochemical process at the core of the technology was featured on July 3 in Joule's Future Energy section, which covers promising energy technologies for a sustainable future and their industrial applicability. Professor Baek's team presented the technology at Joule's invitation.
The research was supported by the National Research Foundation of Korea under the Ministry of Science and ICT (MSIT).
AI-translated from Korean. Quotes from foreign sources are based on Korean-language reports and may not reflect exact original wording.
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