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Abstract The composition and microstructure of heterojunctions could remarkably affect the photo-induced charge separation of semiconductors, thus changing their photocatalytic activity. In this work, a simple solid-state chemical reaction route was developed to fabricate BiOCl/Bi 2 O 2 CO 3 p-n heterojunctions hierarchical nanostructures self-assembled by thin nanoplates. The as-synthesized heterojunctions significantly enhanced photocatalytic activity in comparison with individual Bi 2 O 2 CO 3 and BiOCl. In particularly, the 60% BiOCl/Bi 2 O 2 CO 3 heterojunction exhibited the highest photocatalytic activity, which was around 188 times and 17 times higher than that of pristine Bi 2 O 2 CO 3 under visible and ultraviolet light, respectively. The remarkable enhanced photodegradation performance of heterojunction is ascribed to its higher specific surface area and the efficient separation of photo-generated carriers. Combining with the theoretical and experimental results, the transition paths of electrons and holes between BiOCl and Bi 2 O 2 CO 3 was investigated, therefore the self-photosensitized photocatalytic mechanism of BiOCl/Bi 2 O 2 CO 3 composite has also been well explained. Highlights • A simple and fast solid-state chemical method was firstly used to synthesize BiOCl/Bi 2 O 2 CO 3 composites. • BiOCl/Bi 2 O 2 CO 3 p-n heterojunction exhibited remarkable visible/UV light-driven photocatalytic activity. • A simple and direct photosensitization pathway of RhB over the composite is proposed. [ABSTRACT FROM AUTHOR]

Abstract Sulfide-graphene oxide composites photocatalysts were fabricated through a simple solid-state chemical reaction method under different synthesis conditions. The resulting photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, Nitrogen adsorption-desorption specific surface areas, XPS measurements, UV–vis absorption spectroscopy, Transient photocurrent, and Photoluminescence spectra. The result suggests that ZnS and Bi 2 S 3 nanoparticles well distributed on the graphene oxide nanosheets in the sulfide-graphene oxide composites. Nitrogen adsorption-desorption results indicate that the specific surface areas of the composites increased after the graphene oxide is introduced. XPS measurements suggest that there are interactions between sulfide and graphene oxide. The photocatalytic activities of sulfide-graphene oxide composites were measured by the degradation of methyl orange under UV irradiation. Variation of the synthesis conditions allowed the sulfide-graphene oxide composites possessing different structures and photocatalytic activities as revealed by transmission electron microscopy and photocatalytic measurements. The photocatalytic results indicated that the sulfide-graphene oxide composites exhibited much higher photocatalytic activities than that of pure ZnS and Bi 2 S 3 , and nearly 97% and 90% of methyl orange were degraded over ZnS-graphene oxide and Bi 2 S 3 -graphene oxide after irradiation for 120 min, respectively. The superior photocatalytic activities can be attributed to the high specific surface areas, which is benefical for improving photocatalytic reaction. Futhermore, introducing graphene oxide can effectively reduce the photoinduced electron-hole pair recombination probability, and then improve the photocatalytic activities, which have been proved by the transient photocurrent, photoluminescence spectra, and scavengers measurements. Highlights • Sulfide-GO composites were synthesized by a simple solid-state method. • Effects of GO contents and others on activity of composites were investigated. • The composites exhibited superior activities to pure sulfides. • The superior activity is proved by transient photocurrent, PL and scavengers measurements. [ABSTRACT FROM AUTHOR]

A simple wet chemistry method was employed for the synthesis of graphene oxide-metal sulfide composites. The obtained products were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen absorption–desorption specific surface area and UV–Vis spectroscopy. The study indicates that sulfides nanorods were well dispersed on the graphene oxide nanosheets in the graphene oxide-metal sulfide composites. It was found that the specific surface area of the composites increased with the introduction of graphene oxide. The as-synthesized graphene oxide-metal sulfide composites were used as photocatalysts for the color removal of methyl orange under UV light irradiation. The results indicated that the graphene oxide-metal sulfide composites exhibited improved photocatalytic activity to pure sulfides and commericial sulfides, with nearly 95% and 90% of methyl orange degraded after irradiation for 15 min, respectively. The excellent photocatalytic activity of the composites can be ascribed to the high specific surface area and the reduction of photoinduced electron–hole pair recombination due to the introduction of graphene oxide. With the help of various radical scavengers, O 2 − and h + were proved to be the main reactive species for the color removal of methyl orange. [ABSTRACT FROM AUTHOR]

A simple wet chemical method has been employed to obtain CdS nanorods with the assistance of thioglycollic acid. The as-synthesized samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and UV–vis diffuse reflection spectrum (UV). The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under UV light irradiation. The effects of thioglycollic acid on the morphology and photocatalytic activity were investigated. The results suggest that thioglycollic acid plays an important role in the formation of CdS nanorods. Moreover, the as-synthesized CdS nanorods assisted by thioglycollic acid displayed an excellent photocatalytic performance with a degradation rate of 93% within 40 min under UV light irradiation, even higher than that of commericial CdS. The excellent photocatalytic ability of CdS nanorods can be attributed to the synergic effects of large surface area and unique nanorods structure. With the help of scavengers, · O 2 − was proved to be the main reactive species for the degradation of methyl orange. [ABSTRACT FROM AUTHOR]

A simple solid-state method was employed for the first time to obtain ZnS/graphene nanocomposites. The chemical composition, morphology and properties of the products were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, nitrogen absorption-desorption and UV–vis spectroscopy. The photocatalytic performances of the products were evaluated by methyl orange. The results indicated that nanocomposites exhibited superior photocatalytic activity to pure ZnS, owing to the reduction of photoinduced electron–hole pair recombination induced by the introduction of graphene. In addition, effects of solid-state synthetic conditions on photoactivity were also investigated. It was found that the nanocomposite obtained by the reduction of NaBH 4 exhibited higher photoactivity than that of got by the direct addition of graphene, which can be attributed to the high specific surface area and the enhanced synergetic effect between ZnS and graphene. With the help of scavengers, ·O 2 - was proved to be the main reactive species during the degradation. [ABSTRACT FROM AUTHOR]