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Novel nitrogen-doped carbon quantum dots/Ag 3 PO 4 (NCQDs/Ag 3 PO 4 ) complex photocatalysts were synthesized by a facile precipitation method at room temperature. The physical and chemical properties of Ag 3 PO 4 and NCQDs/Ag 3 PO 4 photocatalysts were detected through X-ray powder diffraction, field emission scanning electron microscopy, UV–vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and electron spin resonance techniques. The as-prepared 3-NCQDs/Ag 3 PO 4 composite exhibited much higher activity than the pure Ag 3 PO 4 for eliminating methyl orange and bisphenol A solution under visible light (λ > 420 nm). Moreover, in the cyclic experiments, the 3-NCQDs/Ag 3 PO 4 exhibited an excellent stability for the decolorization of methyl orange at some level. This suggested that NCQDs played an important role in the process of degradation. The function of NCQDs was discussed and a new mechanism was put forward for the degradation of methyl orange. The high activities and stability were attributed to the transfer of photogenerated charges through the vector of Ag 3 PO 4 → NCQDs → Ag in the photocatalytic process, leading to effective charge separation of Ag 3 PO 4 . [ABSTRACT FROM AUTHOR]

Carbon-supported Ni@Ag core-shell nanoparticles were synthesized and used as the anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The morphology, structure, and composition of the as-prepared electrocatalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). Electrochemical characterizations are performed by cyclic voltammetry (CV), chronoamperometry (CA), linear scan voltammetry with rotating disk electrode (LSV RDE), and fuel cell test. The catalytic behaviors and main kinetic parameters (e.g., Tafel slope, number of electrons exchanged, exchange current density, and apparent activation energy) toward BH oxidation on Ag/C and Ni@Ag/C electrocatalysts are determined. Results show that the as-prepared nanoparticles have a core-shell structure with the average size approximately 13 nm. The kinetics of NaBH oxidation is faster for Ni@Ag/C than that for Ag/C. Among the as-prepared catalysts, the highest transition electron value and the lowest apparent activation energy are obtained on Ni@Ag/C; the values are 4.8 and 20.23 kJ mol, respectively. The DBHFC using Ni@Ag/C as anode electrocatalyst and Pt mesh (1 cm) as cathode electrode obtains the maximum anodic power density as high as 8.54 mW cm at a discharge current density of 8.42 mA cm at 25 °C. [ABSTRACT FROM AUTHOR]

CuO-modified silver bromide (AgBr/CuO) crystal was successful synthesized by a facile method at room temperature. The physical and chemical properties of AgBr/CuO crystals were carefully detected through X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and Electron spin resonance (ESR) techniques. The photocatalytic activity and stability of AgBr/CuO hybrid were evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation. The AgBr/CuO sample exhibited high photocatalytic activity, degrading 92% MO after irradiation for 40 min, which was 3.8 times higher than that of pure AgBr. Both the experimental scavenging results and characterization results revealed that O 2 − acts as the main active specie. Based on above, the high photocatalytic performance is mainly attributed to the abundant of oxygen vacancies, and which further generate lots of superoxide radicals. Moreover, the method by using bromide water to rejuvenate AgBr/CuO could well maintain the photocatalytic activity and stability without any environment pollution. [ABSTRACT FROM AUTHOR]

Abstract: Three kinds of AgBr/Ag3PO4 hybrids were synthesised via an anion-exchange precipitation method and characterised by XRD, XPS, SEM, EDS, and UV–vis. The results showed that AgBr/Ag3PO4 hybrids displayed much higher photocatalytic activities than single Ag3PO4 or AgBr under visible light (λ>420nm), and ·OH and h+ were the major active species during the degradation process. Considering interstitial ions on lattice gap of AgBr are easy to become sliver particle, we deduced the possible photocatalytic mechanism could be ascribed to the synergistic effects of the appropriate valence band position of Ag3PO4 and AgBr, surface plasmon resonance effect of Ag0, reactive radical species Br0, and the Ag vacancy on the surface of catalysts. [Copyright &y& Elsevier]

A h-WO3 decorated Ag-AgCl composite was prepared through facile precipitation and photoreduction methods and demonstrated to be a highly efficient and stable photocatalyst for the degradation of Rhodamine B (RhB) under visible light. Ag-AgCl/h-WO3 exhibited much improved photocatalytic performance was elucidated from the physical-chemical properties of AgCl and h-WO3 and the surface plasmon resonance effect of the Ag particles. The techniques of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectrometry (XPS) and photocurrent were used to characterize crystalline phases, morphology, composition and separation efficiency between electrons (e−) and holes (h+) of the synthesized composite photocatalyst. XPS results confirmed the existence of W5+ and W6+ on the surface of h-WO3 sample, which favored electrons transfer between AgCl and Ag, and generated superoxide radical for the degradation of RhB. The active species trapping experiments results further demonstrated that the formation of superoxide radical during the system. Finally, the underlying photocatalytic mechanism for the removal of RhB by Ag-AgCl/h-WO3 composite was examined. [ABSTRACT FROM AUTHOR]

For detecting the active roles of ZIF-8 in composite photocatalyst, a novel Ag/AgCl/ZIF-8(50%) composite photocatalyst was designately prepared by anchoring Ag/AgCl nanoparticles on the surface of ZIF-8 with 50% content. The adsorption and photocatalytic performance of Ag/AgCl/ZIF-8(50%) were conducted by removal of Rhodamine B (RhB) from aqueous solution under dark and visible light irradiation (λ > 420 nm). The experimental results showed that the as-synthesized Ag/AgCl/ZIF-8(50%) exhibited higher photocatalytic activity than Ag/AgCl. The XRD, TEM, FTIR, DRS, VB XPS, ESR, N 2 adsorption isotherms and active species trapping experiments were used to characterize the performance of the composite photocatalyst. We found that the ZIF-8 in composite photocatalyst not only has the adsorption ability for RhB by its large specific area, but also has the ability for the formation of O 2 · − by an appropriate position of conduction band (CB). A reasonable reaction mechanism with a new perspective on the composite photocatalyst of Ag/AgCl/ZIF-8(50%) was proposed. This insight on the active roles of ZIF-8 in Ag/AgCl/ZIF-8(50%) may open a window for the use of MOF material in photocatalytic field. [ABSTRACT FROM AUTHOR]

A BiOCl thin film has been successfully synthesized on the Bi plate by a facile method at room temperature. Sodium hypochlorite (NaClO) was used as Cl source, in which Cl − was slow-released through redox reaction of NaClO by ethylene glycol (EG). The X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflection spectrometry (DRS) were employed to characterize the structure, morphology, and optical property of the as-prepared BiOCl thin film. The photocatalytic activity and stability of BiOCl thin film was evaluated by degradation of rhodamine B under both simulated solar light and visible light. The results indicated that as-prepared BiOCl thin film had excellent catalytic efficiency and good cycling performance towards photodegradation of RhB. Furthermore, a possible formation mechanism of BiOCl thin film on Bi plate had been proposed. [ABSTRACT FROM AUTHOR]

An unprecedented direct ortho C–H arylation and chlorination of α-ketoesters were successfully accomplished by using a combination of monodentate transient directing group strategy and palladium catalysis. The in situ formed imine changed the bidentate coordination model of α-ketoesters to monodentate, so as to fulfill the ortho C–H activation. Importantly, the key binuclear cyclopalladium intermediate bridged by acetate anion was unambiguously characterized by X-ray diffraction, which solidly supports the proposed mechanism. The practical utility was further depicted as facile access to oral antiplatelet agent Clopidogrel racemate via subsequent two-step derivatization. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon supported Cu-Pd bimetallic nanoparticles were prepared by a successive reduction method in aqueous solution and used as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and fuel cell test. The results show that the size of the crystallite is around 12.5 nm, the Cu 1 Pd 1 /C catalyst presents the highest catalytic activity among all the resultant catalysts, and the DBHFC using Cu 1 Pd 1 /C as anode catalyst and Pt mesh (1 cm × 1 cm) as cathode electrode obtains the maximum power density as high as 39.8 mW cm -2 at a discharge current density of 80.1 mA cm -2 at 20 °C. [ABSTRACT FROM AUTHOR]

The novel BiPO 4 /BiOCl heterojunction composites were successfully fabricated by a facile one-step hydrothermal method. The XRD, SEM, TEM, UV–vis DRS, transient photocurrent and EIS measurements were employed to characterize the phase structures, morphologies, optical properties, and electron–hole separation effect of the photocatalysts. BiPO 4 /BiOCl composites exhibited much higher photocatalytic activity for the methyl orange (MO) degradation than single BiOCl and BiPO 4 under simulated sunlight irradiation. Moreover, the stability test for the optimum synergetic molar ratio of BiPO 4 /BiOCl composites indicated that the synthetic p-n heterojunction BiPO 4 /BiOCl photocatalyst had the gratifying reutilization after five cycles. The results of transient photocurrent measurements and EIS demonstrated that the large enhancement of photocatalytic activity could be mainly ascribed to the surface junction of BiPO 4 /BiOCl composite which can effectively improve electron-hole separation speed during photocatalytic process. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a novel BiOCl thin film with flakelike structures has been successfully prepared through electrochemical method composed of a cathodic electrodeposition and an anodic oxidation at room temperature. The samples obtained at the different oxidation voltages were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), electronic energy spectrum (EDS), and UV–vis diffuse reflectance spectra (UV–vis DRS). The analysis results show that the morphological, structural, and optical characteristics of BiOCl thin films depend markedly on the anode oxidation voltage and the lattice orientation of BiOCl thin film is transformed mainly into (110) surface with the increasing oxidation voltages. The observed results of high-resolution transmission electron microscopy (HRTEM) confirm that pure tetragonal BiOCl thin film with the highly exposed (110) surface is obtained at 2.0V and consists of interlaced nanosheets. First-principles calculations reveal that the existence of BiOCl (110) surface states enhances the electron transition and efficient separation of photo-induced electron–hole pairs. The optimized BiOCl thin film can not only guarantee the intrinsic photochemical properties of BiOCl bulk but also exhibit additional electronic characteristics of BiOCl (110) surface, and consequently the wonderful synergistic effect between BiOCl bulk and BiOCl (110) surface accelerates the efficient separation of electron–hole pairs and produces the high reducing superoxide radicals O2 − ng oxidizing hydroxyl radicals ed for the degradation of organic compounds. For as-prepared BiOCl thin film, the degradation ratio of methyl orange (MO) reaches 98% under 2.5h UV irradiation at the first cycle and still remains 90% at the fifth cycle, and the COD removal efficiency of 50mg/L MO solution over BiOCl thin film achieves 73.47% after 8h reaction time. The BiOCl thin film with highly exposed {110} facets exhibits the excellent photocatalytic performance and potential application in photocatalysis field. [Copyright &y& Elsevier]