Triple‐Functional Amino‐Coordinated Ce–Cr MOF‐on‐MOF Catalyst Unifying Photocatalysis, Biocatalysis, and Photobiocatalysis for Photobiosensing Applications and Binary Dyes Removal

Photobiocatalysis has focused on chemical synthesis, with no prior reports in sensing. In photobiocatalysis, MOFs serve as host matrices for co-immobilizing photocatalysts and biocatalysts but lack intrinsic photobiocatalytic activity. Since most MOFs are oxygen-/hetero-nitrogen-coordination frameworks, developing amino-coordinated MOFs remains challenging. This work reports a novel amino-coordinated MOF(Ce)-on-MOF(Cr) multifunctional catalyst (yield = 78.9%) with triple intrinsic activities-photocatalytic (k_app = 0.2985 min^-1), biocatalytic (V_max/K_m = 2.0 min^-1), and synergistically-enhanced photobiocatalytic (V_max/K_m = 3.45 min^-1)-combined with high coordination stability, and excellent reusability. The MOF(Ce)-on-MOF(Cr) was utilized for multianalyte photobiosensing of o-phenylenediamine, H₂O₂, and glucose, enabling food safety monitoring, water quality assessment, and diabetes diagnosis with extended linear ranges (OPD = 1.0-130.0 µm, H₂O₂ = 0.1-60.0 µm, glucose = 1.0-300.0 µm), markedly lower detection limits (0.2, 0.07, and 0.51 µm, respectively), and shortened response times (3.0 min) compared with conventional biosensors. The MOF(Ce)-on-MOF(Cr) enables triple-mode degradation of methylene blue/methyl violet binary mixtures, achieving degradation efficiencies of 99.43% (methylene blue) and 99.25% (methyl violet) within 6.0 min through photobiocatalysis, revealing 15-fold and 3.3-fold reductions in treatment time relative to photocatalysis and biocatalysis, respectively, while maintaining high operational (10 cycles) and long-term stability (45 days). This study constitutes the first report of an amino-coordinated MOF-on-MOF, the first photobiosensor, and the first MOF exhibiting intrinsic photobiocatalysis, enabling multi-branch applications.