Japanese researchers have developed an innovative method to convert carbon dioxide (CO2) emissions from power plants into valuable organic compounds using pretreated silicon wafers from discarded solar panels. This process not only addresses the pressing issue of greenhouse gas emissions but also repurposes materials that would otherwise be waste. The team from Yokohama National University and other institutions demonstrated how this technique could effectively transform CO2 into useful chemicals, notably formic acid and formamide, utilizing a catalytic reaction that requires no extensive purification of CO2.
In a breakthrough that feels like modern-day alchemy, Japanese researchers have found a way to use waste from old solar panels to turn carbon dioxide (CO2) into valuable organic chemicals. This process not only helps reduce harmful greenhouse gases but also gives a purpose to materials that would otherwise be discarded. A team of chemists from Yokohama National University, Electric Power Development Co., Ltd., and the Renewable Energy Research Center at Japan’s National Institute of Advanced Industrial Science and Technology (AIST) have shared the new study on converting CO2 into valuable compounds. Their study highlights the use of silicon wafers recovered from discarded solar panels as a crucial material in the conversion process.
“In this study, we combined the recycling of waste silicon wafers from end-of-life solar panels with the conversion of CO2 in the exhaust gas from a thermal power plant. The waste silicon wafer acts as a reducing agent of CO2 to organic compounds,” said Ken Motokura, a chemistry professor at Yokohama National University and lead author of the paper. CO2 is a well-known greenhouse gas driving climate change. Capturing and storing it has long been a goal of climate scientists, but this new research takes it one step further—by transforming it into something valuable.
In this case, the team used actual exhaust gas from a thermal power plant, which contained about 14% CO2, and combined it with water, a catalyst called tetrabutylammonium fluoride, and recycled silicon powder. The silicon powder came from crushed solar panel wafers, which were treated with hydrochloric acid (HCl) to boost performance. This pretreatment removed aluminum from the wafer surface, making the reaction more efficient.
“We directly converted CO2 in the exhaust gas, which contained 14% CO2 by volume, from a thermal power plant into formic acid and formamide through a reaction with waste silicon powder, water, and tetrabutylammonium fluoride, a catalyst,” explained Motokura. “No separation and purification of CO2 from the exhaust gas is necessary. The contaminated Al in the waste silicon powder decreases the reaction rate, and appropriate pretreatment with HCl enables enhanced reactivity of the waste silicon.”
The result of this reaction was impressive. The team managed to produce formic acid with yields as high as 73%. Formic acid is used in a wide range of industries, from agriculture to textiles. In addition, the process also generated formamide, a compound used in pharmaceuticals and chemical manufacturing. This chemical transformation is made possible by silicon’s natural ability to donate electrons. When CO2 interacts with the pretreated silicon, the extra electrons help break down and rebuild the molecules into more complex, useful forms. Notably, this reaction is energetically favorable, meaning it doesn’t require extreme heat or pressure to proceed.
What sets this method apart is that it doesn’t need purified CO2. The researchers directly used power plant exhaust, showing that this technique could work in real-world settings without expensive gas separation equipment. The International Renewable Energy Agency (IRENA) predicts that 60 to 78 million metric tons of photovoltaic panels will reach their end-of-life stage by 2050. Without proper recycling systems in place, much of that material could end up in landfills. At the same time, global CO2 emissions remain a major climate concern. This new approach addresses both problems at once.
It turns two forms of waste—CO2 emissions and old solar panels