Study on solar ultraviolet-visible spectrum carbon sequestration based on photochemical-biological synergy

Solar-driven CO₂ reduction technologies are vital pathways to carbon neutrality. This study introduces a suspension-based photocatalytic-biological hybrid system designed to improve solar energy utilization and CO₂ conversion efficiency. The system employs an α-TiO₂ photocatalyst with a narrow bandgap (2.84 eV), high surface area (∼349.98 m²/g), and numerous catalytic active sites for effective UV-light absorption below 436.6 nm. It also integrates the photosynthetic microalga, which absorbs visible light in the wavelength range of 400–700 nm for biological carbon sequestration. This complementary design enables simultaneous absorption of different solar wavelengths, achieving UV–Vis-spectrum sunlight utilization. Under simulated solar irradiation, the system achieved a TCEN of 9.58 mmol g⁻¹ h⁻¹ and a CO₂ conversion rate of 2.46 mmol g⁻¹ h⁻¹, exceeding the performance of the standalone α-TiO₂ system by over 14 times. The hybrid system offers a practical approach for solar-driven CO₂ fixation, overcoming spectral absorption limitations in traditional catalysts and providing a new strategy for efficient solar energy conversion.