SECM screening of the catalytic activities of AuPd bimetallic patterns fabricated by electrochemical wet-stamping technique

Electrocatalyst arrays with various AuPd compositions have been deposited onto an indium tin oxide (ITO) surface by an electrochemical wet-stamping (EWETS) technique. Micropatterned high-strength agarose containing different solutions of chloroauric acid and chloropalladic acid has been used to electrodeposit and generate patterns of AuPd nanoparticle arrays on ITO. The compositions of the AuPd catalysts prepared by EWETS have been determined through a combination of energy-dispersive X-ray analysis (EDX) and X-ray diffraction spectroscopy (XRD). Field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) have been employed to characterize their morphology. The electrochemical activities of the AuPd alloys for H2O2 and FcMeOH+ reduction reactions have been investigated in both redox-competition and feedback modes by means of scanning electrochemical microscopy (SECM). The results obtained from SECM images were well corroborated by calculated heterogeneous electron transfer (HET) rates for the respective AuPd electrodes, demonstrating that the SECM was applicable for the screening of multicomponent alloy catalysts and determining the optimal composition for electrocatalytic reactions.