Monodisperse AuM (M=Pd, Rh, Pt) bimetallic nanocrystals for enhanced electrochemical detection of H2O2

Monodisperse AuM (M = Pd, Rh, Pt) bimetallic nanocrystals were synthesized in oleylamine solvent and studied for electrocatalytic oxidation and sensing of hydrogen peroxide (H2O2). The obtained AuM bimetallic materials appeared as uniformly well-dispersed nanocrystals with narrow size distribution. Electrochemical impedance spectroscopy (EIS) measurements indicated that AuM bimetallic nanocrystals had good conductivity and AuM/C catalysts enhanced electron transfer rate. The catalytic activities, expressed as onset potential of AuM catalysts towards H2O2, reduced in the order of Au (0.44 V) > AuPt (0.33 V) = AuRh (0.33 V) > AuPd (0.21 V). Among these bimetallic nanocrystals, monodisperse AuPd nanocrystals showed the highest catalytic activity towards H2O2 with the detection limit reaching 8.4 μM, and exhibited an enhanced sensitivity of 195.3 μA mM−1 cm−2 at a relatively low test potential (0.25 V vs. SCE). Especially, the AuPd nanocrystals showed a great anti-interference performance in the presence of ascorbic acid (AA), and the degree of interference was calculated to be 0.10% at 0.25 V vs. SCE. The electrocatalytic detection of AuPd nanocrystals towards glucose oxidation exhibited good linear relationship in the range of 0.5–10 mM with high sensitivity of 152.13 μA mM−1 cm−2. These results demonstrated that the AuPd nano-catalyst with high catalytic activity and good anti-interference performance was a promising sensing material for the detection of H2O2. Furthermore, the monodisperse bimetallic nanocrystals with uniform shape and narrow size distribution could be used for micro or nanoelectrode fabrication technology such as screen-printing or ink-jetting, and may bridge the gap between fundamental research and possible biosensor applications.