Single‐Site Ru(II) in a BODIPY‐Based Conjugated Porous Polymer–TiO ₂ Heterostructure: A Case Study of Photothermal Ammonia Synthesis

This work explores the photothermal Nitrogen Reduction Reaction (NRR) to ammonia over a hybrid catalyst composed of TiO 2 and a BODIPY‐based conjugated porous polymer functionalized with a Ru(II) complex. The metal–organic conjugated porous polymer, denoted IEP‐37 (IMDEA Energy Polymer number 37), was synthesized by incorporating a (dipyrrin)(bipyridine)ruthenium(II) complex into a BODIPY network and subsequently integrated with anatase TiO 2 nanoparticles to form a IEP‐37@T‐10 heterostructure. Extended X‐ray absorption fine structure analysis indicates the presence of isolated Ru coordination sites, with no detectable Ru–Ru coordination. Under photothermal conditions, IEP‐37@T‐10 achieved approximately fivefold higher NH 3 production than pristine TiO 2 , and a 3.5‐fold enhancement compared with the Ru‐free hybrid analogue, highlighting the essential role of Ru incorporation in the NRR activity of the system. The hybrid IEP‐37@T‐10 showed good photochemical and thermal stability and retained measurable activity over consecutive reaction cycles. The NH 3 yield obtained under simultaneous light and heat activation exceeded the contributions of the individual photocatalytic and thermocatalytic processes, suggesting a cooperative interaction between photochemical and thermally driven pathways. Time‐resolved spectroscopic studies indicate that Ru incorporation modifies the interfacial charge transfer dynamics between the polymer and TiO 2 , consistent with a direct Z‐scheme‐type charge transfer pathway compared with the Type‐II behavior observed in the Ru‐free hybrid. These findings highlight the influence of Ru incorporation on the charge transfer dynamics of the hybrid system and illustrate the potential of BODIPY‐based polymer–semiconductor heterostructures for light‐assisted nitrogen reduction.