Capture and Photocatalytic Conversion of Low-Concentration CO₂ Using a Self-Assembled CdSe @Carbonic Anhydrase Biohybrid System

Currently, there are large demands for efficient carbon capture and utilization technologies, particularly for low-concentration CO₂. While photocatalytic conversion remains a promising sustainable way, its efficiency is often limited by low CO₂ solubility and competitions of side reactions under diluted CO₂ conditions. To improve this situation, a self-assembled biohybrid system consisting of CdSe quantum dots (QDs) and carbonic anhydrase (CdSe@CA) is designed and synthesized. The biohybrid achieves a CO₂ conversion rate of 47.3 μmol g⁻¹ h⁻¹ in a 100% CO₂ atmosphere with 100% selectivity for CO production. Remarkably, under a 50 vol% CO₂ condition, the CdSe@CA maintains a similar reduction rate, while the performance of CdSe QDs alone drastically drops to 7.6 μmol g⁻¹ h⁻¹. Even under simulated flue gas condition (15 vol% CO₂), the biohybrid can still capture and convert CO₂ at a rate of 8.2 μmol g⁻¹ h⁻¹. Mechanistic analysis reveals that the synergistic effects between CA's ability to rapidly accumulate the reaction substrate, CO₂ (aq), and rich amide groups to stabilize the reaction intermediate Cd-CO₂* together contribute to the biohybrid's excellent low-concentration CO₂ conversion efficiency. This study presents a promising strategy for capturing and utilizing low-concentration CO₂.