Bismuth-polyphenol complex incorporated g-quadruplex-based hydrogel for efficient visible light driven N2 fixation

Abstract

The utilization of natural renewable resources for the development of functional material offers significant economic and environmental advantages. Polyphenols, particularly caffeic acid (CA), direct the self-assembly of biomacromolecules through non-covalent interactions. In this study, a unique strategy was employed to design sustainable functional materials through polyphenol-directed assembly of nucleotides, addressing challenges associated with long-chain oligonucleotides. Using caffeic acid, a less-explored plant-derived polyphenol, guanosine 5′-monophosphate (GMP) was self-assembled into catechol-functionalized G-quadruplex hydrogels, forming well-defined helical fibrils with tunable physicochemical properties. These hydrogels enabled the precise spatial confinement of metal-polyphenol complexes, offering nanoscale control over material properties. Bismuth, chosen for its visible-light absorption, tunable band gaps, and environmental compatibility, was incorporated to exploit its photocatalytic potential. The GC-Bi hydrogel demonstrated exceptional nitrogen fixation performance, achieving an ammonia yield of 905.2 μmol h⁻¹ g⁻¹ (cat.), nearly 3.8 times higher than the pristine CBi complex, with superior selectivity for NH₃. Structural, morphological, and spectroscopic analyses revealed the in-situ heterojunction formation, which results in enhanced charge separation and suppressed electron-hole recombination, underscoring the transformative potential of supramolecular design for scalable applications in environmental remediation, energy conversion, and carbon capture.