Tailored Calcium Silicates Thin Films for Sustainable Carbon Capture Applications

The development of efficient and sustainable strategies for carbon capture and storage is essential to mitigate the escalating impacts of climate change. Mineral carbonation using calcium silicates offers a permanent and environmentally safe route for CO2 sequestration, but conventional approaches are limited by slow kinetics under ambient conditions and often rely on energy-intensive activation methods. Here, we report a novel solid-state approach to enhance the reactivity of natural wollastonite by employing Pulsed Laser Deposition (PLD) to fabricate thin films with tailored morphology. Unlike previous studies relying on synthetic targets, we directly used a natural wollastonite mineral for PLD. By varying the deposition atmosphere, we obtained compact films in vacuum and nanofoams in oxygen. While crystalline wollastonite is not preserved in the deposited films and amorphous calcium silicate phases are instead formed, both film morphologies exhibit significant CO2 uptake through carbonate formation. Comprehensive characterization was performed by a multitechnique approach, including variable-pressure scanning electron microscopy and scanning transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and contact angle measurements. The results revealed that nanofoam morphology promotes enhanced wettability, facilitates rapid CO2 uptake and retention, and ultimately leads to higher carbonation compared to compact films. This additive-free PLD approach provides a potentially scalable, low-energy platform for mineral-based CO2 capture, advancing the use of natural calcium silicates in carbon removal technologies.