COF-Topological Quantum Material Nano-heterostructure for CO₂ to Syngas Production under Visible Light

Efficient solar-driven syngas production (CO+H₂ mixture) from CO₂ and H₂O with a suitable photocatalyst and fundamental understanding of the reaction mechanism are the desired approach towards the carbon recycling process. Herein, we report the design and development of an unique COF-topological quantum material nano-heterostructure, COF@TI with a newly synthesized donor-acceptor based COF and two dimensional (2D) nanosheets of strong topological insulator (TI), PbBi₂Te₄. The intrinsic robust metallic surfaces of the TI act as electron reservoir, minimising the fast electron-hole recombination process, and the presence of 6s² lone pairs in Pb²⁺ and Bi³⁺ in the TI helps for efficient CO₂ binding, which are responsible for boosting overall catalytic activity. In variable ratio of acetonitrile-water (MeCN : H₂O) solvent mixture COF@TI produces syngas with different ratios of CO and H₂. COF@TI nano-heterostructure enables to produce higher amount of syngas with more controllable ratios of CO and H₂ compared to pristine COF. The electron transfer route from COF to TI was realized from Kelvin probe force microscopy (KPFM) analysis, charge density difference calculation, excited state lifetime and photoelectrochemical measurements. Finally, a probable mechanistic pathway has been established after identifying the catalytic sites and reaction intermediates by in situ DRIFTS study and DFT calculation.