Engineering a covalently linked NH2–TiN@PCN-222-Co single atom-based photocatalyst for solar-driven CO2-to-CO conversion

Abstract

In this study, we report the synthesis of NH₂-functionalized titanium nitride (TiN) nanoparticles (NPs) incorporated into single cobalt atom-integrated PCN-222 (denoted as TiN@PCN(Co)-x, where x represents the wt% of TiN) via a solvothermal approach. The amino-functionalized TiN NPs establish strong chemical bonding with PCN-222-Co, facilitating charge transport from the photosensitizer [Ru(bpy)₃]²⁺ to PCN-222-Co and thereby significantly enhancing photocatalytic CO₂ reduction. Notably, the photosensitizer [Ru(bpy)₃]²⁺ plays a crucial role as a primary electron donor, ensuring sustained charge separation and an extended electron lifetime within the TiN@PCN(Co) system. Under optimized reaction conditions, TiN@PCN(Co) with 5 wt% TiN achieves a remarkable CO production rate of 627.42 μmol g⁻¹ h⁻¹ after 4 h of solar light irradiation, demonstrating the synergistic effects of TiN functionalization and photosensitizer-mediated charge transfer in enhancing photocatalytic performance. These studies provide valuable insights into the design of MOF-based hybrid single atom-based photocatalysts for efficient CO₂ reduction and sustainable solar fuel production.