Scientists engineered a wood that gets stronger as it captures CO2

A carbon capture breakthrough.
Ayesha Gulzar
Wood pieces at different stages of modification, from natural (far right) to delignified (second from right) to dried, bleached and delignified (second from left) and MOF-infused functional wood (first on the left).
Wood pieces at different stages of modification, from natural (far right) to delignified (second from right) to dried, bleached and delignified (second from left) and MOF-infused functional wood (first on the left).

Gustavo Raskosky/Rice University 

Although wood is a renewable resource, it takes years to grow and replace, while human activities already ravage forests. A more sustainable alternative made from smaller pieces of wood bonded together, called engineered wood, uses less material than solid wood.

Thus, engineered wood has emerged as a sustainable and environmentally friendly alternative to traditional building materials. However, this wood is prone to warping and deterioration of structural integrity, diminishing its life span.

Scientists at Rice University, Texas, have now developed a special wood that's stronger than its natural counterpart and helps reduce carbon emissions by sequestering carbon dioxide (CO2) from the surrounding air.

A multiaxial top-down strategy

Humans' fight against climate change requires devising integrated concepts that innovate current processes by making them sustainable. Rice University researchers have multiaxially addressed the issues of engineered wood durability and carbon dioxide emissions by developing a special wood infused with a material with a strong affinity for CO2.

In a top-down approach, the team delignified wood; parts of the wood that give it its color was removed, thus creating a hierarchical, porous structure. The porous structure was then infused by soaking it in a solution containing microparticles of a high-performance absorbing material called Metal-Organic Framework (MOF).

MOFs possess a strong affinity for carbon dioxide molecules. The chosen MOF, Calgary framework 20 (CALF-20), outperforms its counterparts regarding performance level and versatility under varied environmental conditions.

Following a top-down approach allowed the researchers to create a structure that closely mimics the natural structure of wood while also making infusing the material throughout the entire structure easier. The result is a functional wood structure that captures and retains CO2 with high selectivity over nitrogen and water vapor.

A simpler and greener process

In the absence of environmentally friendly and sustainable materials for CO2-capturing, the novel enhanced wood structure can be used as a flexible support to deploy CO2-capturing materials in various applications.

"Our process is simpler and 'greener' in terms of both substances used and processing byproducts," says Muhammad Rehman, an assistant research professor in materials science and nanoengineering at Rice University.

The team believes this new type of wood, which can be easily produced using existing technologies, can be used in a wide range of applications, from construction to furniture making, as an eco-friendlier alternative to traditional materials.

The team plans to determine sequestration processes and perform a detailed economic analysis to understand the scalability and commercial viability of the new material.

The research has been published in the journal Cell Reports Physical Science.

Study abstract:

With increasing global climate change, integrated concepts to innovate sustainable structures that can multiaxially address CO2 mitigation are crucial. Here, we fabricate a functional wood structure with enhanced mechanical performance via a top-down approach incorporating a high-performance metal-organic framework (MOF), Calgary framework 20 (CALF-20). The functional wood with 10% (w/w) CALF-20 can capture CO2 with an overall gravimetric capacity of 0.45 mmol/g at 1 bar and 303 K that scales linearly with the MOF loading. Interestingly, the functional wood surpasses the calculated normalized adsorption capacity of CALF-20 stemming from the mesoporous wood framework, pore geometry modulation in CALF-20, and favorable CO2 uptake interactions. Density functional theory (DFT) calculations elucidate strong interactions between CALF-20 and the cellulose backbone and an understanding of how such interactions can favorably modulate the pore geometry and CO2 physisorption energies. Thus, our work opens an avenue for developing sustainable composites that can be utilized in CO2 capture and structural applications.

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