Researchers have developed an in-liquid-plasma-treated titanium dioxide catalyst support decorated with silver nanoparticles as an alternative to carbon catalysts for effective reduction of carbon dioxide. Image: Chiaki Terashima from TUS, Japan.The conversion of atmospheric carbon dioxide (CO2), a greenhouse gas, into useful resources such as carbon monoxide, formic acid, methanol and their byproducts is considered a promising route to mitigating global warming as well as generating economic value.
One approach to CO2 conversion is through electrocatalytic reduction. This process utilizes conventional catalysts, such as lead, silver, tin, copper and gold, supported on conductive carbon to produce an electrode material for selectively reducing CO2. However, the electrode is often exposed to the high pH environment of the electrolyte during electrocatalysis, which can degrade the catalyst support. This is a major cause of concern.
To address this challenge, a team of researchers, led by Kai Takagi and Chiaki Terashima from Tokyo University of Science (TUS) in Japan, has developed a catalyst support based on titanium dioxide (TiO2) powder. This compound is commonly used in sunscreen, paints, coatings, toothpaste, plastics, paper, pharmaceuticals and food coloring. The researchers report their work in a paper in Science of the Total Environment.
To develop this novel catalyst support, the researchers first treated the surface of TiO2 with a safe and inexpensive in-liquid plasma to improve its electrochemical properties. “The in-liquid plasma-treated TiO2 maintained its particle shape and crystal structure,” says Terashima. “Additionally, elemental analysis and evaluation of the interfacial bonding state and electrochemical properties of TiO2 revealed that the redox peaks corresponding to Ti4+ and Ti3+ derived from TiO2 disappeared and the hydrogen overvoltage decreased.” These observations led the team to conclude that tungsten coating or doping occurred on some portions of the reduced TiO2 surface.
The researchers then loaded the TiO2 with silver nanoparticles (AgNPs), which act as catalysts, to develop a gas-diffusion electrode for CO2 reduction. While untreated TiO2 exhibited high selectivity for CO2 and carbon black, in-liquid-plasma-treated TiO2 with 40 wt% AgNP loading demonstrated increased production of hydrogen and enhanced catalytic performance. Given that a suitable ratio of hydrogen to carbon monoxide is important for effective CO2 reduction, the presented technology shows tremendous potential for converting CO2 to useful byproducts, such as syngas, which is considered a clean fuel with very high industrial value.
Additionally, the electrocatalytic reduction of CO2 can be integrated with renewable energy sources such as solar panels or wind power for sustainable and environmentally friendly CO2 conversion. This work thus represents a significant step towards efficiently tackling greenhouse gas emissions and fighting climate change.
“Hopefully, the present study will promote research on technologies for carbon neutrality and carbon recycling, in alignment with the United Nations Sustainable Development Goals 7, 12, and 13 on affordable and clean energy, responsible consumption and production, and climate action, respectively,” says Terashima. “These, in turn, will open doors to the realization of a carbon-neutral and sustainable future.”
This story is adapted from material from Tokyo University of Science, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.