Nano-heterostructures of topological insulators and soft metallo-supramolecular polymer for solar fuel production.

Topological insulators (TIs) feature metallic surface states, and their integration into nano-heterostructures for catalysis is valuable, as these robust surface states can act as electron reservoirs. Here, we report a rational design strategy that embeds ultrathin BiSe and Bi2Se3 nanosheets into a dynamic metallo-supramolecular gel (Zn-TPY-POR CPG, Zn-CPG), creating soft hybrid nano-heterostructures BiSe@Zn-CPG and Bi2Se3@Zn-CPG for the photocatalytic CO2 reduction reaction (CO2RR). The pristine Zn-CPG forms a hierarchically organized, sheet-like morphology that provides light harvesting and molecular-level adaptability, while the TI nanosheets couple strongly within the coordination polymer gel through the electrostatic interaction. This integration establishes robust electron transfer pathways, optimizes interfacial interactions, and tunes the charge transfer dynamics, as confirmed by Kelvin probe force microscopy (KPFM) and density functional theory (DFT) analyses. Notably, BiSe@Zn-CPG exhibits nearly ten-fold higher CO2RR activity than pristine Zn-CPG. In situ DRIFTS and theoretical investigations demonstrate that the Bi3+ sites of the TIs, possessing a 6s2 lone pair, serve as effective CO2 binding sites and stabilize key reaction intermediates during CO2 reduction, demonstrating the synergy between the TIs and Zn-CPG network to enhance the photocatalytic performance. By integrating quantum materials with metallo-supramolecular gels, this work establishes a novel strategy for creating adaptive hybrid nano-heterostructures for sustainable energy conversion.