Co-tuning composition and channel-rich structure of Ag-Pd alloys toward sensitive electrochemical biosensing

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Noble-metal nanostructures are promising for biosensing applications owing to their fantastic physicochemical properties, but the rational design of their easy-accessible and reactive surface is still challenging. This work is devoted to the interfacial engineering of Ag-Pd alloys, including tuning alloy composition and geometric structure, to promote the electrochemical biosensing performance. Through a co-tuning tactic with controlled reduction, channel-rich Ag1Pd3 alloys with optimal electronic configurations and accessible active surface are successfully obtained, which afford high sensitivity, outstanding selectivity and excellent repeatability to detect H2O2 and glucose biomarkers. As experimentally and theoretically evidenced, tailoring the composition of Ag-Pd alloys ameliorates electronic configurations due to ligand effects, which can optimize the binding with the key intermediate of OH*, and thereby boost electrochemical kinetic steps on surface. Meanwhile, tuning geometric structure with abundant channels enables fast transport of analytes toward largely-exposed active sites. Providing an atomic-level interpretation of structure-dependent biosensing, this work is anticipated to offer guidelines for the development of efficient sensing platforms.