Morphology-controlled peroxidase-like cuprous oxide-platinum cubes for dual-mode sensing of mercury ions

It is still a challenge to achieve high-precision, rapid, efficient, and accurate detection of toxic mercury ions in complex environmental medium. In this protocol, the controllable and multi-functional Cu2O/Pt cubes were first utilized to construct a colorimetric and photoelectrochemical (PEC) dual-mode sensor for mercury ions. For the colorimetric sensing, compared with Cu2O and Pt particles alone, the Cu2O/Pt cubes creatively prepared by sequential electrodeposition method have simulated peroxidase synergistic catalytic activity against chromophore 3,3',5,5'-tetramethylbenzidine (TMB) upon exposure to H2O2. Meanwhile, Pt nanoparticles (NPs) can selectively reduce Hg2+ ions, and the resulting Pt-Hg alloys can attenuate the catalytic oxidation. Based on the similar signal suppression strategy, the Cu2O/Pt cubes could also be utilized for PEC sensing of Hg2+ ions since Cu2O is a well-known p-type semiconductor. Based on this unique dual-signal output sensing mechanism, the constructed sensor can be competent for the measurement of Hg2+ in practical settings. This strategy creatively combines the dual functions of Cu2O and Pt to the dual signal expression of sensors. Moreover, the homogeneous distribution of Cu2O/Pt cubes prepared by electrodeposition ensures the stability of dual signal expression, especially for modified electrodes. Additionally, the designed dual-mode sensor has good performance in sensitivity, specificity, simple operation as well as cost-effectiveness and rapid response. In particular, the dual-output sensing strategy enables self-confirmation of detection results, which greatly improves the reliability of the sensor.