Facet-Dependent Electrochemical Behavior of Au–Pd Core@Shell Nanorods for Enhanced Hydrogen Peroxide Sensing

Development of advanced sensing systems capable of trace analysis for small biomolecules is promising yet challenging in both physiological and pathological fields. Nanostructures with a specific surface where the reaction process happens directly govern the overall sensing performance because of the facet-dependent effects on the atomic level. Using core–shelled Au@Pd bimetallic nanorods as the platform, we herein studied the impacts of surface atomic arrangement on the performance of electrochemical H 2 O 2 biosensing. Specifically, Au@Pd with a (100)-facet (Au@Pd-100) exhibited more than 3 times higher sensitivities than Au@Pd with a (111)-facet in H 2 O 2 detection. Based on the theoretical calculations, this strong facet-dependence was attributed to the efficient charge transfer from Au core to Pd (100) shell and favorable intermediate adsorption energy over (100)-facet. The Au@Pd-100 exhibited great H 2 O 2 sensing performance with high sensitivity (up to 383.0 μA mM –1 cm –2 ECSA ), relatively low detection limit (∼1.0 μM) and wide applicable detection range (1.0 to 1.75 × 10 3 μM), which also ensured the high efficiency of Au@Pd-100 sensor in real-time monitoring of H 2 O 2 released from the cancer cells. In depth interpretation of facet-dependent effect in this work not only highlights the significant role of the surface engineering in performance improvement but also can offer guidelines for the fabrication of efficient biosensors.