Search

Modification of TiO2 (P25) with Au–Cu bimetallic nanoparticles (NPs) was successfully achieved via a deposition–precipitation method with urea (DPU) followed by radiolytic reduction. This deposition procedure ensures the complete adsorption of Au and Cu ions onto TiO2. Small Au–Cu NPs homogeneous in size were obtained. The alloyed structure of Au–Cu NPs was confirmed by HAADF-STEM, EDS, HRTEM and XPS techniques. The photocatalytic properties of the modified TiO2 have been studied for photodegradation of methyl orange. The modification with Au–Cu bimetallic nanoparticles induces an enhancement in the photocatalytic activity under UV irradiation. The highest photocatalytic activity was obtained with Au–Cu/TiO2 (Au/Cu = 1 : 3). Bimetallic Au–Cu NPs act as efficient electron scavengers increasing the photocatalytic activity under UV light. [ABSTRACT FROM AUTHOR]

Herein, a coprecipitation method used to synthesize CuS nanostructures is reported. By varying the reaction time and temperature, the evolution of the CuS morphology between nanoparticles and nanoflakes was investigated. It was found that CuS easily crystallizes into sphere-/ellipsoid-like nanoparticles within a short reaction time (0.5 h) or at a high reaction temperature (120 °C), whereas CuS nanoflakes are readily formed at a low reaction temperature (20 °C) for a long time (12 h). Photodegradation experiments demonstrate that CuS nanoflakes exhibit a higher photodegradation performance than CuS nanoparticles for removing rhodamine B (RhB) from aqueous solution under simulated sunlight irradiation. Carbon nanotubes (CNTs) were further used to modify the photodegradation performance of a CuS photocatalyst. To achieve this aim, CNTs and CuS were integrated to form CNT/CuS hybrid composites via an in situ coprecipitation method. In the in situ constructed CNT/CuS composites, CuS is preferably formed as nanoparticles, but cannot be crystallized into nanoflakes. Compared to bare CuS, the CNT/CuS composites manifest an obviously enhanced photodegradation of RhB; notably, the 3% CNT/CuS composite with CNT content of 3% showed the highest photodegradation performance (η = 89.4% for 120 min reaction, kapp = 0.01782 min−1). To make a comparison, CuS nanoflakes and CNTs were mechanically mixed in absolute alcohol and then dried to obtain the 3% CNT/CuS-MD composite. It was observed that the 3% CNT/CuS-MD composite exhibited a slightly higher photodegradation performance (η = 92.4%, kapp = 0.0208 min−1) than the 3% CNT/CuS composite, which may be attributed to the fact that CuS maintains the morphology of nanoflakes in the 3% CNT/CuS-MD composite. The underlying enhanced photocatalytic mechanism of the CNT/CuS composites was systematically investigated and discussed. [ABSTRACT FROM AUTHOR]