Microwave-Assisted Fabrication of Bimetallic PdCu Nanocorals with Enhanced Peroxidase-Like Activity and Efficiency for Thiocyanate Sensing

Nanomaterials with enzyme-like characteristics (nanozymes) are an emerging alternative of traditional bioenzymes that holds great promise in a variety of fields. The activity and efficiency of most current nanozymes, however, are lower than those of natural enzymes, which will inevitably hinder their wider applications. Thus, the development of new nanozymes with favorable catalytic properties is urgently desired. In this work, we reported a coral-structured bimetallic PdCu nanozyme that exhibited enhanced peroxidase activity and efficiency. The coral-like nanozyme fabricated by a microwave-assisted wet-chemical method was composed of assembled PdCu branches. In a comparison with pure Pd, the bimetallic PdCu had an enhanced ability to catalyze the reaction of colorless tetramethylbenzidine (TMB) to its blue oxide (TMBox) in the presence of hydrogen peroxide (H₂O₂). X-ray photoelectron spectroscopy and theoretical calculation indicated that the insertion of Cu atoms into the Pd lattice would increase the Pd⁰ proportion and decrease the adsorption difficulty of H₂O₂, both of which finally resulted in improvements in the catalytic activity and efficiency. It was further found that thiocyanate (SCN^–) could inhibit the color reaction by decreasing the activity of PdCu selectively. On the basis of this principle, SCN^– in the much wider range of 0.001–100 μM could be detected, along with a limit of detection down to 1 nM