Gold-palladium bimetallic nanoalloy decorated ultrathin 2D TiO₂ nanosheets as efficient photocatalysts with high hydrogen evolution activity

In this work, a novel AuPd bimetallic nanoalloy decorated ultrathin 2D titanium dioxide (TiO₂) nanosheet with high H₂ evolution activity was prepared via a facile in situ synthesis method. The physical and photophysical properties of the as-prepared AuPd/TiO₂ nanosheets were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) and surface photocurrent spectroscopy (SPC). The photocatalytic H₂ evolution experiments indicate that the AuPd co-catalysts can efficiently promote the separation of photogenerated charge carriers in TiO₂, and consequently enhance the H₂ evolution activity. The 0.3 wt% AuPd/TiO₂ sample shows the highest catalytic activity, and the corresponding H₂ evolution rate is 526 μmol h^-1 g^-1, which is 31 times higher than that of pure TiO₂ under simulated sunlight (λ > 300 nm) irradiation. A possible mechanism of the enhanced simulated sunlight catalytic performance of AuPd bimetallic nanoparticle (NP) decorated TiO₂ nanosheets is proposed to guide further improvement of desirable functional materials. It is expected that the AuPd decorated TiO₂ nanosheets obtained via a simple synthesis approach can be used as efficient photocatalysts and exhibit promising potential for new energy applications.