A RUDN chemist developed a new method of obtaining a porous carbon material on the basis of Chinese flour and water. The samples of the material exhibited high electrocatalytic activity in the course of production of hydrogen – an eco-friendly energy source. The results of the work were published in Electrochimica Acta.
Electrocatalytic production of hydrogen is a promising method of eco-friendly energy generation. In this type of reactions catalysts are electrodes made of platinum and other precious metals, and scientist are looking for a cheaper option. Around 20 alternative electrocatalysts based on different metals and carbon have been suggested in the last 5 years. Together with his Chinese colleagues, Rafael Luque, a visiting scholar at RUDN, developed a new method for obtaining the carbon material of electrocatalytic hydrogen production.
The new catalyst is based on fermented flour used for baking a specific type of Chinese bread. It is made of wheat and contains only 1% of yeast. The scientists developed a recipe for "cooking" the material: the flour mixed with distilled water should be spread out in a thin layer on a teflon surface and kept this way at 80°C for one hour to fix its form. After that it should be heated in an autoclave up to 350° C. This hydrothermal treatment secures the durability and high porosity of the samples. Finally, the material should be baked in a nitrogen environment at 700° C, 850° C, and 1,000° C. The chemists used different temperatures to find out the most optimum conditions.
The obtained nitrogen-containing porous carbon turned out to be quite durable. The authors of the work made an electrode for electrocatalytic hydrogen production from a piece of the new material and a stainless steel wire. The electrochemical experiment was conducted in acid environment. The porous three-dimensional structure of the material gave it catalytic properties: the reagents were quick to penetrate the pores and to contact large surfaces which made electron transmission easier The electrocatalytic activity of the new material is higher than in currently known carbon-based catalysts and is comparable to metal ones. The best results were shown by the material heated to the highest temperature of 1,000° C. The researchers checked its stability and found out that its electrocatalytic activity remained unchanged for at least 11 hours.
"The synthesis of nitrogen-containing porous hydrogen from fermented flour using hydrothermal treatment and pyrolysis is a cost-efficient, eco-friendly, and simple method," says Rafael Luque, Director of the Center for Molecular Design and Synthesis of Innovative Compounds for Medicine, and a visiting scholar at RUDN. "A simple synthetic protocol could yield 44% of a high surface area porous carbon with a 3-dimensional porous structure. The activity of the material in electrocatalysis is better than that of most reported non-metal heteroatom-doped carbon catalysts and comparable to that of some metal ones. This makes flour-based carbon electrodes highly promising for a future potential implementation in industry."
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The participants of the study also represented Changchun Institute of Applied Chemistry and the University of the Chinese Academy of Sciences. The work was supported by the 5-100 Program.
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http://dx.doi.org/10.1016/j.electacta.2018.09.010
