Efficient photothermal CO₂ methanation over NiFe alloy nanoparticles

The massive emissions of CO₂ from the utilization of fossil fuels have caused a series of environmental issues and climate change. Driven by the fast development of green hydrogen and CO₂ capture technologies, the hydrogenation of CO₂ to hydrocarbon fuels and chemicals is becoming a promising process for the reduction of carbon footprint and the storage of renewable energy. Photothermal catalysis enables efficient CO₂ conversion under mild conditions.

A study led by Prof. Kang Cheng (College of Chemistry and Chemical Engineering, Xiamen University) and Prof. Ye Wang (College of Chemistry and Chemical Engineering, Xiamen University) evaluated catalysts using a high-pressure fixed-bed reactor quartz reactor with a square cavity in the middle to introduce light. The study is published in the journal Science China Chemistry.

A series of NiFe alloy photothermal catalysts were synthesized using the urea-assisted precipitation method for CO₂ methanation, in which the bimetallic NiFe nanoparticles with Al₂O₃ as the structural promoter and Ni/Fe atomic ratio of 7 had the best catalytic performance.

The CO₂ conversion rate can reach 98%, the CH₄ selectivity is 99% without external heating. The catalyst can operate stably for more than 100 hours. Compared with other catalysts, it was found that the small alloy particle size (~21 nm) and the unique layered structure of the NiFeAl catalyst could enhance the LSPR effect of NiFe alloy.

Compared with Ni or Fe, NiFe alloys can promote CO₂ methanation synergically. The temperature on the surface of the catalyst was detected to be as high as 356 °C under light irradiation observed by an infrared camera, indicating that the catalyst was able to efficiently convert light energy into heat energy.

This paper not only prepared an efficient catalyst for CO₂ methanation but also provided the idea for the structural design of a photothermal catalyst.