Nanochemistry crosses path with macrostructures: Chinese Researchers reveal the synthesis of a macroscopic aerogel from carbonitride nanomaterials which is an exceptional catalyst for the water-splitting reaction under visible-light irradiation. The study has been published in the journal Angewandte Chemie and introduces new opportunities to the material properties of melamine-derived carbonitrides.
Melamine can be polymerized with formaldehyde to provide an extremely durable and light resin, but it can also be condensed to develop nanostructures of carbonitride materials. These assemblies made up of nitrogen and carbon join the honeycomb-like electronically active network of graphene with some additional functionality of nitrogen.
Exploring for ways to assemble these nanostructures into a steady macroscopic architecture, Xinchen Wang and his team at Fuzhou University in China have at present prepared a catalytically highly active and stable lightweight material, which aids well in artificial photosynthesis and provides very exciting structural and electronic properties.
Aerogels are gels but without water—up to 99% of their structure is air. This porosity offers them an enormous surface perfect for sensory or catalytic application. As carbonitrides are materials with very remarkable graphene-like properties and nanostructure but nitrogen functionality, it has for long been sought for use in a controlled macroscopic assembly. "Since CN is rich in nitrogen-containing groups, it is expected that CN may have interesting assembly behaviors like proteins or peptides in biological systems," the Authors said.
The improved surface area and higher number of catalytic sites would transform these aerogels into extremely functional macroscopic materials. Using only physical interparticle forces inherent to the nanoparticles, the Researchers prepared the aerogel by allowing a colloidal aqueous solution of carbonitride nanoparticles to settle first into a hydrogel, then converting it into a stable aerogel using a conventional freeze-drying technology.
"This method has several advantages, including scalability for mass production and low cost," the Authors said. Along with a platinum co-catalyst, the aerogel was a lot better a photocatalyst for hydrogen evolution than the bulk carbonitride, and hydrogen peroxide was produced from pure water under visible-light irradiation when the bulk carbonitride failed.
Therefore, by combining forces of physical and chemical features from the nano to the macroscale, they have developed a new lightweight material with superior catalytic prospects. This potential application of melamine building blocks directs the way forward to new materials, and is far apart from the proven mass production of the durable and light, but not so thermostable melamine plastic dishes.