Troublesome Waste PV Panels Reborn as Hydrogen and High Value-Added Silica [Science Reader]

Up to Five Times Higher Efficiency Than Conventional Methods...
"Negative Cost Structure" Achievable

Simultaneous Solution for Waste Panel Disposal and Clean Hydrogen Production Expected

A new technology has been developed that enables the simultaneous production of high-purity hydrogen and high value-added silica using silicon recovered from end-of-life photovoltaic (PV) waste panels. This technology is attracting attention as an eco-friendly method to convert discarded PV panels—once considered a troublesome waste due to the difficulty of landfilling and incineration—into valuable resources.

On April 6, UNIST announced that Professor Paek Jongbeom's team from the Department of Energy and Chemical Engineering has developed a highly efficient process that utilizes silicon from waste PV panels to simultaneously produce high-purity hydrogen and silica, an industrial high value-added material.

Conceptual diagram of a technology that continuously removes the silica layer on the silicon surface through collisions and friction of beads in a ball mill process, sustaining the reaction while simultaneously producing high-purity hydrogen and high-value-added silica. Provided by research team

Silicon can react with water to produce hydrogen and silica, but in actual reactions, the formation of a silica film on the surface blocks water access, causing the reaction to stop prematurely. As a result, the hydrogen yield from conventional thermochemical methods has fallen far short of its theoretical maximum.

The research team developed a dynamic mechanochemical process that removes the silica protective film without using strong chemical agents. By rotating silicon and water in a vessel containing small beads, repeated collisions between the beads and the silicon particles continuously break the silica film, exposing fresh reactive surfaces.

Experimental results showed that approximately 1,706 mL of hydrogen was produced per 1 gram of commercial silicon. This is 99.6% of the theoretical maximum yield of 1,713 mL g⁻¹ and up to five times higher efficiency compared to conventional thermochemical methods (18–28%). Experiments using silicon powder directly obtained from waste PV panels also demonstrated about 98% hydrogen production efficiency.

The silica produced alongside hydrogen also exhibited excellent performance as a catalyst support. When the research team applied this silica to a nickel catalyst for the CO₂ methanation reaction, it achieved higher conversion rates and methane selectivity than catalysts based on commercial silica. The result was attributed to the abundant hydroxyl groups (-OH) on the surface, which led to a more uniform dispersion of catalyst particles.

Research team photo. From left: Professor Paek Jongbeom, Professor Lim Hangwon, Researcher Xiao Yuanhuo (first author), Researcher Guan Runan (co-first author), Researcher Jiwon Goo (co-first author). Provided by UNIST

The process also proved highly economical. Even without accounting for silica by-product revenues, the hydrogen production cost was found to be tens to thousands of times lower than that of conventional thermochemical processes. With the addition of silica sales, the research team noted that a "negative cost structure" is possible, meaning the more hydrogen produced, the greater the profit.

Notably, the continuous process achieved higher production rates and energy efficiency than the batch process, confirming its potential for large-scale industrial applications. The technology is being evaluated as an alternative solution capable of addressing both the rapidly growing problem of PV waste panel disposal and the need for clean hydrogen production.

Professor Paek Jongbeom stated, "The key strength of this technology is that it enables the production of eco-friendly hydrogen from silicon extracted from waste PV panels, while simultaneously yielding industrially useful silica. By converting difficult-to-dispose-of waste panels into high value-added resources, this technology will contribute to establishing a resource-circulating economy."

The results of this research were published online on March 27 in Joule (Cell Press), an international academic journal in the energy field. The core mechanochemical technology behind the process was also separately featured in Joule’s special editorial section, "Future Energy."

This content was produced with the assistance of AI translation services.