Researchers at ETH Zurich have created a pioneering building material that actively captures and stores carbon dioxide. The material combines a hydrogel with photosynthetic cyanobacteria. These microorganisms absorb CO₂ from the air and convert it into biomass and carbonate minerals, making it both a living and carbon-storing system.

Sustainable Innovation for the Built Environment

The hydrogel serves as a medium for the bacteria and allows light, water, and nutrients to pass through. As the cyanobacteria grow, they perform photosynthesis, absorbing CO₂ and producing biomass. Uniquely, they also trigger the formation of solid carbonates like lime. These minerals reinforce the material while locking in carbon in a stable, long-lasting form.

This dual process stores more CO₂ than many biological systems. In lab tests, the material bound 26 milligrams of CO₂ per gram—more than triple the amount stored by recycled concrete. As such, it offers a promising solution for turning buildings into active carbon sinks.

Designed to Support Growth and Light

The material can be shaped using 3D printing. Researchers tailored the design to maximise light exposure and nutrient flow. They created geometries that help the bacteria grow and function for over a year. Over time, the once-soft structure hardens from the inside as minerals accumulate.

This method reduces energy use, supports circular construction, and enhances material durability—making it suitable for architectural applications like façades or interior features that sequester CO₂ over their lifetime.

Real-World Applications in Venice and Milan

Two installations demonstrate the material’s potential. At the 2025 Venice Architecture Biennale, ETH’s Picoplanktonics showcased tall, tree-trunk-like structures made from the material. Each one can absorb up to 18 kilograms of CO₂ annually—similar to a mature pine tree.

At the 24th Triennale di Milano, the installation Dafne’s Skin explored microbial patinas on wooden façades. The living skin of cyanobacteria alters the surface over time, turning signs of decay into a design feature. It also continues to bind CO₂ from the environment.

Towards Biotic Architecture

This material is part of ETH Zurich’s ALIVE initiative. The programme encourages collaboration between scientists, architects, and designers to create bio-integrated materials. These living systems offer low-energy, regenerative solutions for the built environment.

By embedding life into architecture, this innovation opens new paths toward climate-resilient and carbon-negative construction.

Source: ETH Zurich