Black silicon catalyst converts carbon dioxide to methane using sunlight

A research team from National Taiwan University has created a photoelectrochemical catalyst that converts carbon dioxide into methane using sunlight. The device combines a specially engineered black silicon surface with copper-zinc alloy nanoparticles. In testing, the optimized catalyst produced methane with a Faradaic efficiency of approximately 40% while requiring less energy to initiate the reaction compared with conventional copper catalysts.

The study, published in Applied Catalysis B: Environment and Energy, used advanced synchrotron X-ray spectroscopy and in situ Raman spectroscopy to monitor the catalyst during operation. The researchers found that the catalyst does not remain static but continuously adjusts its electronic structure under illumination. Zinc helps stabilize metallic copper, enabling the catalyst to bind carbon dioxide reaction intermediates more effectively.

Simultaneously, sunlight generates energetic electrons that accelerate the chemical steps leading to methane formation. These two effects work cooperatively, making methane production both easier and more selective. The discovery of this dynamic behavior provides insight into why the catalyst performs better than previous designs.

Professor Hao Ming Chen, co-corresponding author of the study, said understanding how catalysts dynamically respond to sunlight while operating allows researchers to engineer their behavior for cleaner energy technologies. The principles uncovered may help develop more efficient systems for converting carbon dioxide into a variety of valuable chemicals and fuels.

Such technologies could contribute to future carbon recycling strategies, renewable energy storage, and sustainable chemical manufacturing. The work represents a step toward using carbon dioxide as a raw material for solar fuel production rather than solely viewing it as a greenhouse gas.

The research was conducted by Ruspika Sundaresan and colleagues at National Taiwan University. The findings are based on experimental observations of the catalyst's electronic structure changes during active carbon dioxide conversion.