Dual-strain engineering in Pd metallene for ultrasensitive tetracycline electrochemical biosensing

Precise modulation of strain and electronic structure via atomic-level Mo and Cr co-doping in Pd metallene (MoCr-Pdene) significantly enhances electrocatalytic tetracycline (TC) sensing. Conventional Pd-based sensors suffer from weak TC affinity and sluggish kinetics due to surface inertness and biofouling. MoCr-Pdene overcomes these limitations through synergistic dual-strain effects, including compressive strain (from Cr) stabilizing the lattice and tensile strain (from Mo) redistributing surface charge. This strain-charge synergy shortens the Pd-O adsorption distance (1.82 Å), enhances adsorption energy (0.86 eV), and accelerates electron transfer, enabling an ultra-low detection limit of 27 nM, which represents ten-fold improvement over commercial Pd/C. The co-doped metallene exhibits exceptional stability (retaining 80 % of its signal after 120 days) and anti-biofouling capability in matrices. Importantly, MoCr-Pdene serves as a dual-functional platform for clinical diagnostics and environmental monitoring, quantitatively assessing TC biodegradation by black soldier fly larvae (BSFL) and gut microbiota (degradation rates: 97.96 % in frass, 90.67 % in BSFL). These results pioneer atomic-scale strain-electronic engineering for next-generation antibiotic sensing and sustainable bioremediation.