Periodic Reporting for period 1 - BioNanoCarb (Ordered Nanoporous Carbon Architectures from Biobased Building Blocks)
Periodo di rendicontazione: 2022-10-01 al 2024-09-30
The synthesis and creation of mostly manmade petroleum-based materials in the modern age, associated with increased carbon dioxide emission and environmental pollution, pushed humankind into a new era in our history, the “Anthropocene”, described by climate change and depletion of fossil fuels along with irreversible geological changes. Worldwide efforts started to change the odds by implementing and intensifying sustainable development strategies aimed at utilising carbon neutral or even carbon negative renewable energy- and resource-based technologies. In the project "BioNanoCarb" we look at more sustainable, environmentally benign technologies to produce state-of-the-art nanoporous carbons, a type of material that is expected to be an important element in future high-performing energy storage systems and water purification devices. Therefore, our project contributes directly to our efforts of "responsible consumption and production", identified as one of the sustainable development goals (SDGs, SDG 12) of the United Nations (UN). These materials will be important in realizing affordable and clean energy (SDG 7) through more efficient energy-storage devices that can better support intermittent renewable energy systems. Furthermore, the structures at the focus of our project have potential for applications in more efficient water treatment systems, contributing to our efforts for clean water (SDG 6).
The work in the beginning focused on identifying environmentally benign strategies to fabricate the target material, ordered hierarchically porous (micro-mesoporous) carbon structures. Thus, we thoroughly reviewed the existing literature, and critically discussed available synthetic strategies. According to the result of our literature-review, soft templating methods appear to be the most promising approaches, as they can be seen as energy- and resource-efficient direct methods to synthetize these materials compared to multistep hard-templating (or nanocasting) systems. Several promising soft-templating methods have been realized by others using biobased carbon precursors, catalyst-free reactions, and benign crosslinkers. Nevertheless, they all use petroleum-derived Pluronic® surfactants as structure-directing agents. In our experimental work, therefore, our aim was to replace these surfactants to more sustainable, biosourced alternatives. While looking for possible alternatives, we got inspired by chitosan/fatty acid supramolecular assemblies, widely reported in the literature, and believed that such system may be suitable to construct a novel soft-templating method that uses only biobased building blocks. We studied chitosan/fatty acid coacervates in aqueous solutions, and their semi-solid structures after crosslinking the system using glyoxal. We cured and then carbonized this material at high temperature, leading to porous carbon structures. Since ordered nanoporous systems could not be realized this way, we moved to another strategy, by using the monomeric unit of chitosan, D-glucosamine, and the hydrothermal method without using a crosslinker. D-glucosamine has more mobility than chitosan, and is believed to better fit to the self-assembly process according to our understanding. The resulting hydrothermal carbon was treated at high temperature to obtain nanoporous carbons. This synthetic strategy was the most promising, and may initiate new research directions for more discoveries.
We identified key technologies to prepare state-of-the-art ordered meso-microporous carbons through sustainable, environmentally benign ways. We critically evaluated existing methods and directed the scientific community towards important research areas to address knowledge gaps. We introduced a novel concept of using a biosourced surfactant to realize a fully biobased soft templating system, the first of its kind. We hope that our efforts open new avenues for the development of biobased state-of-the-art ordered meso-microporous carbons.