Tuning Bismuth Metal-Organic Framework Topology for Enhanced Photocatalytic NO Oxidation

Precise topological-structural control over bismuth-based metal-organic frameworks (Bi-MOFs) is hampered by the challenge of balancing thermodynamics and kinetics. Such balance is achieved in three well-defined Bi-MOFs with crystalline, semi-crystalline, and amorphous topologies via a straightforward secondary building unit approach in bismuth-2-aminoterephthalic acid (Bi-BDC-NH₂). The structure of Bi-BDC-NH₂ is confirmed by single-crystal X-ray diffraction (XRD) to consist of BiO₉ nodes. The amount of 2-aminoterephthalic acid is varied to modulate the topology via competitive complexation and thus control the thermodynamic and kinetic nucleation products. Through regulating the ligand-to-metal ratio of H₂BDC-NH₂ to Bi, an appropriate balance of the thermodynamic-versus-kinetic structural "trade-off" is achieved. The fine topologies of Bi-MOFs are determined by single-crystal XRD, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption fine structure. For the first time, it is reported that applying Bi-MOFs with varying topological structures as photocatalysts for removing nitric oxide (NO) demonstrates that the amorphisation improves the photogenerated charge separation efficiency and adsorption and activation of O₂. This work offers a guide in complex topological-structural control, which is conducive for those to develop highly efficient MOFs-based photocatalysts.