Newswise — Separation processes play a crucial role in purifying and concentrating target molecules during water purification, pollutant removal, and heat pumping, contributing to approximately 10-15% of the world's energy consumption. To enhance the energy efficiency of these processes, it is essential to advance the design of porous materials, potentially leading to a substantial reduction in energy costs, up to 40-70%. Precise control over the pore structure is the key approach to achieve improved separation performance.
Porous carbon materials offer a notable advantage in this regard, as they consist of a single type of atom and have already found widespread use in separation processes. These materials possess significant pore volumes and surface areas, making them highly effective in gas separation, water purification, and storage. Nonetheless, their pore structures often exhibit considerable heterogeneity and lack sufficient design options, presenting several challenges that limit their broad applicability in separation and storage applications.
A group of Japanese researchers, led by Associate Professor Tomonori Ohba from Chiba University, along with master's students Mr. Kai Haraguchi and Mr. Sogo Iwakami, has successfully created a new carbon composite called fullerene-pillared porous graphene (FPPG) using a bottom-up approach. This innovative material offers highly designable and controllable pore structures. The team published their findings in a recent article available online since June 16, 2023, which appeared in Volume 127, Issue 25 of The Journal of Physical Chemistry C on June 29, 2023.
The fabrication of FPPG involved a unique process of forming a fullerene–graphene–fullerene sandwich structure. The researchers achieved this by introducing a fullerene solution to the graphene and gently coating the resulting composition, repeating the lamination process from 1 to 10 times. This approach allowed them to precisely control the fullerene filling within the porous graphene, giving them novel tuning capabilities in the synthesis process.
Following the creation of FPPG structures with varying fullerene filling ratios, the researchers conducted experiments and employed grand canonical Monte Carlo simulations to study their water vapor adsorption properties. They observed that when the fullerene filling was at 4% in the graphene, there was only a slight adsorption of water vapor. As they increased the fullerene filling to 5%, the amount of adsorption decreased further due to the collapse of nanopores in the laminar porous graphene.
However, a significant and unexpected outcome occurred when the filling ratio was raised close to 25%. FPPG with 25 ± 8% fullerene exhibited the highest water vapor adsorption capacity at 40% relative humidity, attributed to the production of large, uniform nanopores, as emphasized by Dr. Ohba.
On the other hand, increasing the fullerene filling ratio beyond 25%, up to 50% fullerene, led to a decline in the adsorption capabilities. The Monte Carlo simulations confirmed these findings, showing that the excessive fullerene content reduced the nanopores, thereby hindering water cluster formation.
Dr. Ohba is optimistic that the bottom-up technique and the designable, controllable pore structures of FPPG could pave the way for the development of additional innovative materials. These materials have the potential to significantly enhance the performance of gas and liquid purification and concentration processes. As a result, the production costs of various products relying on separation processes could be substantially reduced.
The introduction of novel porous carbons like FPPG has the exciting prospect of revolutionizing storage and purification applications. By increasing energy efficiency and cost-effectiveness, these advanced materials hold the promise of transforming various industries.
RSS