Bi-Doped Pd Aerogels with Tensile-Strain-Induced Cascade Orbital Hybridization Boost H₂O₂ Selective Activation for...

The selective activation of H₂O₂ into hydroxyl radicals (•OH) through the synergistic interplay between the nanozyme's internal orbital interactions and external orbital coupling with intermediates presents an important scientific challenge. In this study, we demonstrate that PdBi aerogels with controllable tensile strain first enhance the Pd d orbital energy level through p-d orbital hybridization, and subsequently, the hybridized Pd d orbitals couple sequentially with the molecular orbitals of H₂O₂, forming a cascade of orbital hybridizations. High-performance liquid chromatography quantitative analysis reveals that the engineered PdBi aerogels remarkably improve •OH selectivity from 73.3% to 95.4%, importantly boosting both the activation efficiency and selectivity. Experimental studies and theoretical calculations have demonstrated that the hybridization of the d orbitals of Pd and the p orbitals of Bi in PdBi aerogels initially raises the d-band energy level of the Pd atoms. During the activation of H₂O₂, the high-energy 4d_xz/yz and 4d_z ² orbitals of Pd further hybridize with the 2π* and 5σ orbitals of H₂O₂, thereby enhancing the orbital interaction with H₂O₂ and creating optimal conditions for O-O bond cleavage and consequently enhancing the efficiency of •OH generation. Capitalizing on the differential reactivity patterns of various pesticides with PdBi aerogels, we develop a colorimetric sensor array for the discrimination and simultaneous detection of pesticide residues. Taking chlorpyrifos as an example, the detection limit is 0.23 μM, demonstrating good detection sensitivity. This work presents an orbital-level design strategy for creating highly selective nanozymes in H₂O₂ activation systems.