Synthesis of AuPd nanoparticle-decorated graphene-coated ZnO nanorod arrays with enhanced photoelectrochemical performance and stability

Abstract

AuPd nanoparticle-decorated graphene-coated ZnO nanorod (ZNR) array electrodes (ZNR@Gr/AuPd) were synthesized via electrostatic self-assembly followed by solution reduction methods. The morphologies of ZNR@Gr/AuPd were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), which indicated that ZNR was well-coated by graphene with 3–5 layers and uniformly decorated with AuPd nanoparticles (about 5 nm). UV-Vis diffuse reflectance and photoluminescence spectra were obtained to analyze the optical properties. The photoelectrochemical (PEC) properties were also evaluated; the results indicated that the photocurrent density was 2.27 mA cm⁻² at 0.8 V versus Ag/AgCl, which was 7.1 times that of bare ZNR. The sample also displayed enhanced PEC stability (91.3%), which prevented photocorrosion. Finally, a proposed PEC mechanism of ZNR@Gr/AuPd was illustrated to explain the charge transfer and the role of graphene and AuPd nanoparticles in the improvement of PEC performance and stability. The ZNR@Gr/AuPd electrode shows excellent PEC performance and stability, exhibiting promising potential in the generation of H₂.