In a notable advance for smart construction materials, researchers have developed a bio-inspired cement–polyvinyl alcohol (PVA) composite (CPC) that significantly boosts thermoelectric efficiency, opening the door to self-powered buildings and infrastructure.
Study: Bio-inspired thermoelectric cement with interfacial selective immobilization towards self-powered buildings. Image Credit: Mohammed_Al_Ali/Shutterstock.com
Published in Science Bulletin, the study introduces a composite that mimics the layered stem structure of plants. By aligning cement and PVA hydrogel layers, the material achieves a Seebeck coefficient of −40.5 mV/K and a figure of merit of 6.6 × 10-2—both record-setting for cement-based systems.
Rethinking Cement: From Structural Backbone to Functional Material
Cement is the backbone of global construction, but beyond its mechanical strength, it also has untapped potential as a functional material. Thanks to the movement of ions within its porous structure, cement exhibits ionic thermoelectric properties. These arise from differences in how positively and negatively charged ions interact with pore walls, creating a thermoelectric effect when exposed to temperature gradients.
The challenge lies in efficiency. In standard cement, densely packed pores limit ion mobility, especially for ions with inherently higher diffusion rates, leading to a narrow difference in mobility and a low Seebeck coefficient. To enhance performance, researchers have turned to nature for inspiration.
Plant xylem tissue provides a compelling model. These channels are not only aligned for efficient transport, but also selectively interact with ions via hydrogen bonding along the walls. This dual function supports both rapid movement and selective retention of ions, key traits for improving thermoelectric behavior.
By borrowing this strategy, the research team designed a cement-based material that mirrors the structure and function of xylem. Their goal was to create aligned pathways that promote ion transport while controlling selective immobilization.
Crafting the Composite: Bio-Inspired from the Ground Up
Using an ice-templating method, the team created a unidirectionally aligned cement skeleton (SC). Cement slurry was poured into a polytetrafluoroethylene (PTFE) mold and frozen using liquid nitrogen. A polydimethylsiloxane wedge introduced a bidirectional freezing gradient, forming a layered ice structure that guided the alignment of cement particles.
As the ice melted, the cement hydrated and set into a rigid, aligned framework. This structure was then infiltrated with PVA hydrogel, resulting in the final CPC material.
Why It Works
The strength of the CPC lies in its interfacial ion control. PVA hydrogel layers serve as fast-conducting paths for OH⁻ ions, while the interfaces between cement and PVA form strong bonds with Ca2+ ions. This selective immobilization creates a pronounced difference in ion mobility, a crucial factor in improving thermoelectric performance.
The layered structure amplifies these effects by providing a high density of interfaces, which serve as active sites for ion interactions. As a result, the CPC not only achieved a Seebeck coefficient of −40.5 mV/K and a figure of merit of 6.6 × 10-2, but also exhibited mechanical strength and energy storage capacity, enabling it to function as a component in self-powered systems.
A Step Toward Self-Sustaining Infrastructure
This breakthrough highlights the potential of nature-inspired design in advancing energy-harvesting materials. The CPC outperformed previously reported cementitious thermoelectric materials by a factor of ten in Seebeck coefficient, five in power factor (168.6 μW/mK2), and six in figure of merit.
By integrating both energy harvesting and storage, CPCs could one day power embedded electronics, such as sensors and communication devices, within roads, bridges, and buildings. These self-sustaining systems would reduce external power needs and support the growing demand for smarter, more efficient infrastructure.
Journal Reference
Wang, Y. et al. (2025). Bio-inspired thermoelectric cement with interfacial selective immobilization towards self-powered buildings. Science Bulletin. DOI: 10.1016/j.scib.2025.03.032, https://www.sciencedirect.com/science/article/abs/pii/S2095927325002816
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