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In this paper, three-dimensional TiO2 nanoflowers (NFs) were prepared by a facile hydrothermal method, and Ag3PO4 was grown in situ following alkali treatment to design and synthesize a Ag3PO4/OH/TiO2 catalyst with excellent photocatalytic activity under visible light. The test results show that the photocatalytic degradation performance of TiO2 NFs after alkali treatment and Ag3PO4 loading is significantly improved. This is because the alkali treatment and the introduction of Ag3PO4 can provide a large amount of –OH, which can be converted to ˙OH under UV irradiation, followed by an increase in the number of active radicals to enhance the photocatalytic degradation performance. Meanwhile, the introduction of Ag3PO4 can effectively improve the light absorption ability of the photocatalyst. Moreover, the in situ growth of Ag3PO4 on TiO2 NFs can construct a high-quality Ag3PO4/TiO2 heterojunction to promote the charge separation and transport. Therefore, the degradation rate of Ag3PO4/OH/TiO2 can reach 90% after 30 min for degrading 3 mg L−1 RhB under visible light. The Ag3PO4/OH/TiO2 photocatalyst designed in the present work provides a new tool for the degradation of organic dyes. [ABSTRACT FROM AUTHOR]

Three-dimensional rose-like ZnO (R-ZnO) is an appealing photocatalyst due to its remarkable properties, while it is also essential to boost its current visible light photocatalytic performance. In this study, R-ZnO was prepared by the hydrothermal method, and oxygen vacancies and Ag nanoparticles were introduced by calcining the ZnO precursor in an argon atmosphere and the photoreduction method, respectively, to improve the photocatalytic activity. The prepared Ag/Ar-ZnO exhibits a narrower bandgap of 2.79 eV, highly increased light absorption both in the ultraviolet and visible light regions, and improved charge separation and transfer efficiencies induced by the relatively higher number of oxygen vacancies and the localized surface plasmon resonance (LSPR) effect of the Ag nanoparticles. Therefore, Ag/Ar-ZnO displays a significantly enhanced visible light photocatalytic performance, with a methyl orange (MO) photodegradation rate constant (Kap) that is 2.41 and 3.59 times higher than those of Ag-ZnO and Ar-ZnO, respectively. This research offers an effective way to enhance the photodegradation performance of R-ZnO under visible light irradiation. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have great potential for producing photoelectrocatalyzed hydrogen and degrading pollutants, owing to several factors such as high porosity and tunable semiconductor-like properties. Wide band gaps, which restrict their use to only UV light induced reactions, and low efficiencies for the separation of photogenerated charge carriers (electrons and holes) pose significant challenges to the widespread applications of MOFs. In this study, a hierarchical hollow Pt@H-UiO-66-NH2/CdS ternary catalyst was designed and synthesized. The immobilized CdS nanoparticles (NPs) in this catalyst endow the MOF H-UiO-66-NH2 with high visible light absorption ability and the Pt NPs serve as electron sinks to improve charge carrier separation. Furthermore, the hierarchical hollow structure of H-UiO-66-NH2 in the composite contributes to boosting light absorption and shortening the distance for charge transfer. As a proof of principle, Pt@H-UiO-66-NH2/CdS catalyzes methylene blue (MB) degradation with a high rate constant of 1.025 × 10−2 and hydrogen production with a rate of 12 810 μmol g−1 h−1, the latter of which is about 2.3, 11.7 and 173 times higher than those of Pt@UiO-66-NH2/CdS, H-UiO-66-NH2/CdS and Pt@H-UiO-66-NH2, respectively. [ABSTRACT FROM AUTHOR]

Highly efficient 2D/2D layered heterostructure of nickel oxide (NiO) and molybdenum sulphide (MoS2) has been fabricated for the photoelectrochemical (PEC) water splitting and degradation of Bromophenol Blue (BPB) under visible light. The XRD spectra confirm mixed characteristic peaks of MoS2 and NiO in the nanocomposite. SEM displays flower-like patterns of pure and composite material with the 2D nanosheets layer structure. The band gap reduction (2.25–1.72 eV) is due to the incorporation of NiO in MoS2 for visible light harvesting. TEM confirms the homogeneous distribution of 2D/2D nanosheets. The excellent interfacial coupling in strong 2D/2D interactions boost the electro and photocatalytic activities. 15.0% NiO showed excellent PEC activity toward OER with maximum photocurrent density of 1.57 mA cm−2, which influenced the overall water splitting at lower potential, ensuring visible photoresponse. The maximum photodegradation performance for highly toxic BPB was achieved by the photocatalyst, which contains 15.0 wt% NiO in NiO/MoS2 composite. It displays the highest conversion efficiency (∼87.0%) for BPB owing to exposed active sites via Mo–Ni–S linkages. Defects in NiO/MoS2 offer favorable reaction dynamics to PEC OER, which are helpful in tuning the band potentials. [ABSTRACT FROM AUTHOR]

FeWO4 was synthesized by a simple solvothermal method. The band structure of FeWO4 was investigated on the basis of density functional theory calculations. The FeWO4 photocatalyst showed lower photocatalytic activity for the degradation of doxycycline hydrochloride under visible light irradiation. Kinetic studies using radical scavenger technologies suggested that hydroxyl radicals were the dominant photo-oxidants. In order to enhance the photocatalytic activity of FeWO4, FeWO4 was used to activate peroxymonosulfate to degrade doxycycline hydrochloride under visible light irradiation. The influences of the peroxymonosulfate dosage, doxycycline hydrochloride concentration, inorganic anions, natural organic matter and pH value on activating peroxymonosulfate to degrade doxycycline hydrochloride were investigated in detail. The mechanism of FeWO4 activating peroxymonosulfate was proposed and proved by radical quenching experiments, electron spin resonance analysis, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, transient photocurrent responses and cyclic voltammetry. It can be found that the combined activation effects of photo-generated electrons and transition metals on peroxymonosulfate to produce sulfate radicals could enhance the degradation efficiency obviously. [ABSTRACT FROM AUTHOR]

An efficient, one-pot wet chemical synthesis strategy for the preparation of NiO nanoparticles has been reported. The nanostructured NiO has surface bound hexamine and it has emerged as a proficient catalyst for the conversion of carbon dioxide (CO2) into formaldehyde with a maximum turnover number of 369 in the presence of blue LED light. The nano-photocatalyst has shown great catalytic efficiency (in terms of the turnover number) and excellent reusability for the photoreduction of CO2. To the best of our knowledge this will be the first report on photoreduction of CO2 to formaldehyde in water under visible light irradiation using NiO nanoparticles as the photocatalyst. The as-prepared NiO nanomaterial has been thoroughly characterized using several spectroscopic and microscopic techniques, e.g. UV-vis spectroscopy, PXRD, XPS, SEM, FESEM and TEM. The mechanism of formation has been predicted from a detailed FTIR analysis. [ABSTRACT FROM AUTHOR]

High-efficiency sunlight energy usage and low carrier recombination have attracted significant attention for the exploration of novel photocatalyst candidates. In this work, BiOCl nanosheets showing various (001)/(102) facet ratios were synthesized by a simple hydrolysis method under different pH conditions by using BiCl3 as a precursor. The inherent relationship among the morphology, exposure facets and photocatalytic performance of BiOCl was visualized via adjusting the synthesis parameters during the hydrolysis process. The results indicate that the suitable (001)/(102) facet ratio, abundant hydroxyl groups on the surface, and the negative potential surface of BiOCl are important factors for the enhancement of its photocatalytic degradation rate of organic pollutants. Besides, the negative potential surface of BiOCl helps in the adsorption of Rhodamine B (RhB) molecules readily, which act as a sensitizer to widen the response range of BiOCl from ultraviolet light to visible light. The sensitized BiOCl photocatalyst with good matching (001)/(102) crystal planes indicates an excellent photocatalytic behavior, and it can decolorize a RhB solution completely under visible light within 40 min, which is even higher than that of commercial TiO2 under UV light irradiation. This work provides a facile route and good idea for the application of photocatalysis for the removal of cationic pollutants in the wastewater purification field. [ABSTRACT FROM AUTHOR]