<p>Coal-fired power plants are among the largest contributors of CO₂ emissions, highlighting the need for sustainable energy solutions. Photocatalytic process is an innovative and sustainable approach for reducing CO₂ emissions from coal-burning processes, utilizing crab shell-derived materials as catalysts. The aquaculture sector disposes of approximately 40% of fish waste, the Crustacean trade generates 6–8 million tons of shell trash every year worldwide. Calcium carbonate (CaCO₃) from crab shell are transformed into effective photocatalysts through thermal modifications. The processed crab shell was examined by Fourier transform infrared spectroscopy, particle size analysis, thermogravimetric analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The crab shell-based calcium oxide nanoparticle catalysts have a wide surface area and active sites that capture and transform CO₂ under UV light exposure. The integration of crab shell-based photocatalysts for removal of CO₂ from flue gas offers a dual advantage: valorization of seafood waste and reduction of greenhouse gases. The maximum CO₂ removal efficiency achieved was 74% with 40–50&#xa0;min of irradiation. This work lies in converting naturally abundant crab shell waste into calcium oxide nanoparticles with high CO₂ adsorption and reduction potential, thereby integrating waste valorization with environmental remediation. This research aligns with Sustainable Development Goals (SDG) 9 and 13 emphasizing innovation in sustainable materials and climate action.</p>