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The majority of current photodegradation experiments utilize high-energy xenon lamps as simulated sunlight, which ignores the changeable weather in nature. In this paper, we synthesize a flower-like Bi2WO6/CdS heterojunction viaa surfactant assisted one-pot hydrothermal strategy. Owing to the suitable energy level match, an S-scheme charge transfer route is achieved in the composite, which possesses tremendous practical application potential in photocatalytic degradation. In an outdoor environment with cloudy weather, the obtained Bi2WO6/CdS S-scheme heterojunction exhibits superior tetracycline decomposition performance, with 67.12% degradation efficiency within 150 min, higher than those of pristine B2WO6(64.15%) and CdS (19.62%). Bi2WO6/CdS also presents excellent photocatalytic activity in a large volume of tetracycline solution without magnetic stirring to simulate a motionless wastewater environment. After 4 cycles of the photodegradation test, little loss of tetracycline removal efficiency is observed for Bi2WO6/CdS, suggesting its strong durability. Moreover, the Bi2WO6/CdS composite also reveals favorable photodegradation ability toward various dye pollutants under real natural sunlight irradiation, with degradation efficiencies of 78.11%, 92.79%, and 95.96% for methyl orange, methylene blue, and rhodamine B after natural light irradiation for 80, 60 and 40 min, respectively. This work could provide a significant impact on the promotion of Bi2WO6-based photocatalysts into real-world applications of wastewater treatment.

Hydrogen has great promise as an energy carrier superior to traditional fossil fuels. Electrochemical water splitting is expected to be an effective and sustainable method for producing high-purity hydrogen fuel cleanly. The hydrogen evolution reaction (HER) is the cathodic reaction in the electrochemical water-splitting process and requires efficient catalysts. However, the state-of-the-art Pt suffers from high cost and rare reserves, which significantly limit its extensive applications in the hydrogen evolution reaction for water splitting. Although its catalytic activity still falls far short of expectations, molybdenum sulfide has emerged as one of the most promising catalysts for HER due to its abundant reserves and high tunability. Here, we have reported the synthesis and HER catalytic performance of a hybrid lanthanum sulfide/molybdenum sulfide (La2S3–MoS2) catalyst. The formation of molybdenum sulfide nanosheets in situwith lanthanum sulfide deposition was achieved through a facile one-pot solvothermal strategy. The present catalyst displayed much superior activity for HER to pristine and commercial molybdenum sulfide; low overpotentials of 205 mV, 277 mV, 336 mV and 455 mV for the current densities of 10 mA cm−2, 50 mA cm−2, 100 mA cm−2and 200 mA cm−2were obtained, respectively, together with a low Tafel slope of 51 mV dec−1. Moreover, the present catalyst exhibited excellent stability in long-term hydrogen evolution. The remarkable HER performance might be mainly due to the expanded interlayer distance and the nano-interfaces between the molybdenum sulfide and lanthanum sulfide segments, which induced an increased exposure of active sites and a modified surface electronic structure.

Abstract

Exploring highly efficient electro-catalysts is of significant urgency for the widespread uptake of the direct methanol fuel cells (DMFCs). Pt–Co nanocrystals have attracted considerable attentions because of their superior catalytic performance toward both methanol oxidation and oxygen reduction in the preliminary assessments. This Research Article presents a Pt–Co bimetal catalyst that is synthesized through a facile coreduction strategy. The Pt–Co nanocrystals have concave cubic shape with a high uniform size of 7–9 nm and Pt-rich surfaces. The catalysis of the concave cubic Pt–Co nanoparticles toward both methanol electrochemical oxidation reaction (MOR) and oxygen electrochemical reduction reaction (ORR) is evaluated. In comparison with the commercial Pt/C catalyst (Johnson Matthey), the present concave cubic Pt–Co catalyst displays superior performances in not only catalytic activity but also durability. The concave Pt–Co catalyst also shows higher activities than spherical and cubic Pt–Co nanoparticles. The dramatic enhancement is mainly attributed to its alloyed composition, Pt-rich surface and the concave nanostructure. The results of our research indicate that the concave Pt–Co nanocrystal could be a promising catalyst for both MOR and ORR. The present work might also raise more concerns on exploiting morphology and composition of nanocrystal catalysts, which are expected to provide high catalytic performance in electrochemical reactions.

Exploiting high catalytic activities and superior durability is significant for the lifetime and the cost of electro-catalysts for oxygen reduction reaction (ORR). Pt–Ni nanocrystals have attracted considerable attention owing to their exceptionally catalytic performance. However, the durability of Pt–Ni nanoparticles in acid media is still far below satisfaction. Consequently, improving the durability is extremely urgent for the application of Pt–Ni catalysts. To this end, we herein develop Pt–Ni–Ir ternary nanocrystals with dendritic shape, which are synthesized through a facile one-pot strategy. Such nanostructures featured with multibranches show an area specific activity of 1.58 mA cm–2, seven times more than that of the commercial Pt/C catalyst (0.21 mA cm–2). More importantly, the dendritic Pt–Ni–Ir catalyst displays extraordinarily high durability. In contrast to the commercial Pt/C counterparts, which exhibit losses of 53.2% in EASA and 41% in area specific activity after 12 000 cycles of sweeping in the potential range of 0.6–1.1 V, only respective losses of 5.5% and 6% are detected for our dendritic Pt–Ni–Ir catalyst. The high activity and remarkable durability are mainly attributed to the dendritic morphology and the introduction of Ir. This work demonstrates that the Pt–Ni–Ir dendritic nanostructures are promising electro-catalysts for ORR.

A novel intercalation compound of Dion–Jacobson-type perovskite calcium niobate (KCa2Nb3O10) with the nitroxy radical 2,2,6,6-tetramethylpiperidyl-1-oxy (TEMPO) task-special ionic liquid (TEMPO-IL) has been successfully synthesized through a facile and rapid electrostatic self-assembly deposition (ESD) technique. The TEMPO-IL/Ca2Nb3O10nanocomposite has been examined for the electrochemical detection of nitrite using cyclic voltammetry and differential pulse voltammetry techniques. The electrochemical studies demonstrate that TEMPO-IL/Ca2Nb3O10nanocomposite detects nitrite linearly over a concentration range of 4.4 × 10−4to 6.0 × 10−3M.A novel intercalation compound of Dion–Jacobson-type perovskite calcium niobate (KCa2Nb3O10) with the nitroxy radical 2,2,6,6-tetramethylpiperidyl-1-oxy (TEMPO) task-special ionic liquid (TEMPO-IL), has been successfully synthesized through a facile and rapid electrostatic self-assembly deposition (ESD) technique. The TEMPO-IL/Ca2Nb3O10nanocomposite has been examined for the electrochemical detection of nitrite using cyclic voltammetry and differential pulse voltammetry techniques.

g-C3N4-assisted interface engineering has been developed as an effective method to improve the efficiency and stability of perovskite solar cells (PSCs). However, most of the reported works used g-C3N4-induced single-interface modification, which is difficult to passivate the bilateral interfaces of the perovskite layer at the same time. In this paper, we fabricated two kinds of C3N4materials simultaneously (w-CN and y-CN) after the twice calcination of melamine and used them in the bilateral interface modification toward all-inorganic PSCs. The two kinds of C3N4play different roles in different interface engineering. On the front interface, w-CN could optimize band level arrangement and improve the perovskite film quality, which contributes to the efficiency of the device. On the back interface, y-CN could also improve the film quality of the perovskite layer, accelerating the extraction of charge carriers. The champion efficiency of the CsPbIBr2-based device treated by the bilateral interface is significantly enhanced from 7.8 to 10.1%. Moreover, the modified perovskite film exhibits negligible degradation after 40 min of exposure in the ambient environment with a relative humidity of 70%, while the pristine perovskite film has a rapid degradation within 20 min.

Highly uniform twofoldshaped CeO2dendrites were successfully prepared in large quantities by using an approach that involves the thermal decomposition of the precursor. The precursor with an average size of 10 μm was prepared from the reaction of CeNH42NO36with CONH22at 160 °C in a waterdiethanolamine DEA complex solution. The influence of DEA on dendrite formation is discussed. The dendritic pattern of precursor is almost retained in the asprepared product. The optical absorption spectrum indicates that the CeO2dendrites have a direct bandgap of 3.42 eV. The electrochemical characteristic of the CeO2dendrites structures have been studied by cyclic voltammetry. It was found that the CeO2dendrites can greatly improve the electrontransfer ability. © WileyVCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Novel hierarchical nanostructures of nickel, which were assembled by well-aligned hexagonal nanoplatelets, were fabricated through a simple solution method. The process involved the reduction of nickel dimethylglyoximate with hydrazine under controlled conditions. Based on a series of contrast experiments, the formation mechanism of the flowers was proposed, which could be ascribed to the cooperative effect of the complexant of dimethylglyoxime, a proper reaction rate, and inherent magnetic interactions. The present work provided an example for the synthesis of magnetic assembly nanostructures through properly selection of the reaction conditions, which were independent of any surfactants or external magnetic field.

A novel chemical reduction route was designed for the synthesis of nickel nanocrystals with distinct flowery shapes by using a mixture of two complexes of Ni(N2H4)32+ and Ni(dmg)2 (nickel dimethylglyoximate) as the nickel source. Formation of these flowers, comprising spherical centers and swordlike petals, was related to the varying stability and structural properties of the two precursors as well as the reaction conditions. Investigations of the time-dependent shape-evolution process indicated that spherical particles were formed first as flower centers, and then swordlike petals grew radially from the particle surfaces. A rational mechanism of formation was proposed on the basis of a range of contrasting experiments. Compared with bulk nickel, these nanoflowers exhibited an enhanced coercivity (Hc) and a decreased saturation magnetization (Ms); this fact is attributed to their peculiar morphology. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Guest-guest exchange method is utilized to prepare a novel water-soluble metalloporphyrin manganese(III) meso-tetrakis(N-methylpyridinium-4-yl) porphyrin (MnIIITMPyP) intercalated layered lanthanum niobate KLaNb2O7. By the characterization of XRD, MnIIITMPyP cation is hypothesized to form an inclined monolayer between LaNb2O7[?] nanosheets. The as-prepared nanocomposite MnIIITMPyP-LaNb2O7 has good electrocatalytic activities toward oxidation of nitrite. A linear range of 2 x 10[?]5 [?] 2.14 x 10[?]2 mol L[?]1 with a detection limit of 1.3 x 10[?]5 mol L[?]1 is concluded by detection of amperometric response of the MnIIITMPyP-LaNb2O7 modified electrode in nitrite solution, the mechanism of the nanocomposite toward electrocatalytic oxidation of nitrite is proposed.

The carbon-based NiS2nanorods (NiS2@C) were prepared by chemical deposition and sulfidation with nickel dimethylglyoximate (Ni(DMG)2) as the starting agent. The nanorods were analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy for chemical analysis. Structural characterization revealed that NiS2existed on the surface of the rod and in the internal channels of the rod. In 0.5m H2SO4solution, NiS2@C has lower onset potential and higher current density than NiS2. The results suggest that C improves the electrical conductivity of the NiS2electrocatalyst, and the carbon film-based rod-like NiS2is a more effective nanocomposite of hydrogen evolution.

A novel layered nanocomposite, MnTSPP/Cu-LHs, was constructed by the fabrication of Cu2(OH)3NO3nanosheets and manganese 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anions, MnTSPP. The obtained novel lamellar composite was characterized by using XRD, FTIR, UV–vis, SEM, and EDS. Meanwhile, the morphology and the zeta potential of the obtained Cu-LHs colloidal dispersion were measured by AFM and a Zetasizer Nano instrument, respectively.A novel layered nanocomposite, MnTSPP/Cu-LHs, was constructed by the fabrication of Cu2(OH)3NO3nanosheets and manganese 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anions, MnTSPP. The obtained novel lamellar composite was characterized by using XRD, FTIR, UV–vis, SEM, and EDS. Meanwhile, the morphology and the zeta potential of the obtained Cu-LHs colloidal dispersion were measured by AFM and Zetasizer Nano instrument, respectively.

A sandwich-structured nanocomposite of α-ZrP/CoTMPyP [5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrinatocobalt(III)] was fabricated via electrostatic interaction between cobalt porphyrin and α-ZrP nanosheets. The obtained material was used as a modifier on a glassy carbon electrode (GCE) to test the electrocatalytic performance toward oxygen reduction, the results indicated that dioxygen was reduced to H2O2via two-electron transfer.

The polyaniline/bismuth oxybromide (PANI/BiOBr) hybrids materials have been synthesized hydrothermally in the presence of PANI. The PANI/BiOBr hybrids materials were confirmed by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and ultraviolet–visible diffuse reflectance spectroscopies. Among the hybrid photocatalysts, PANI/BiOBr-0.2 showed the highest photocatalytic properties for the degradation of rhodamine B (RhB), and the increased photocatalytic properties could be due to photosensitization and the inhibited electron–hole recombination.

Bi2S3/SnS2heterostructured photocatalysts were synthesized from BiOI, SnCl4⋅5H2O and NH2CSNH2using an economic and simple hydrothermal method. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and ultraviolet-visible diffuse reflectance spectroscopy. The photodegradation activities of the Bi2S3/SnS2heterostructured photocatalysts were estimated by degrading rhodamine B under simulated sunlight supplied by irradiating with a 350W Xe lamp. Bi2S3/SnS2photocatalysts were prepared using varying percentages of Bi2S3. The sample containing 13% Bi2S3had the most efficient photocatalyst performance among the tested samples. The photocatalytic mechanism involves heterojunctions formed in the Bi2S3/SnS2, which promoted effective separation of photoinduced electrons and holes.

A cationic metalloporphyrin 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrinatoiron(III), FeTMPyP, was successfully intercalated into layered titanoniobate (KTiNbO5) through a guest-exchange method by using PrNH3+–TiNbO5as an intermediate. The characterizations for the intercalation compound FeTMPyP–TiNbO5were carried out by means of XRD, elemental analysis, and UV–vis absorption spectra. Electrochemical studies reveal that the glass carbon electrode modified with FeTMPyP–TiNbO5hybrid exhibits good redox activity.

A robust hydrothermal route has been designed for synthesis of uniform Fe3O4@carbonaceous core–shell nanowires with self-assembled Fe3O4nanowires as the core component and carbonaceous matter as shell. The formation mechanism of the self-assembled Fe3O4@carbonaceous core–shell nanowires is investigated in detail.

Porous copper nanorods with rectangular cross sections have been successfully prepared in high yield via a hydrothermal reduction process at a relative low temperature. The phase and morphology of products were analyzed by X-ray powder diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). An interesting red shift was observed in the optical absorption measurement and attributable to the porous nanorod with rectangular cross sections.

High-yield synthesis of a new type of flowerlike nickel nanostructure was reported. The method involved the growth of β-Ni(OH)2flowers from the alkali solution of Ni(dmg)2(nickel dimethylglyoximate), followed by reduction in hydrogen atmosphere at 450 °C for 1 h. Compared with that of bulk nickel, thus-prepared nickel flowers showed a much enhanced coercivity.

Hexagonal-like Fe3O4nanoparticles were hydrothermally synthesized from iron chloride, using diethylene glycol (DEG)–water mixed solvent as the medium. The as-prepared powders were characterized in detail by conventional techniques such as X-ray diffraction, and transmission electron microscopy, and their magnetic properties were evaluated on a vibrating magnetometer.

Nickel nanocrystallites with hexagonal flake-like morphology with a side length of 200–400 nm and a thickness of 20–30 nm were prepared by reduction of nickel dimethylglyoximate with hydrazine hydrate in a solution. Selected area electron diffraction (SAED) pattern revealed that the flakes were single crystals. It was found that the precursor, nickel dimethylglyoximate, played an important role for the formation of these flakes. Magnetic properties of the product were measured by a vibration sample magnetometer (VSM).

Guest-guest exchange method is utilized to prepare a novel water-soluble metalloporphyrin manganese(III) meso-tetrakis(N-methylpyridinium-4-yl) porphyrin (MnIIITMPyP) intercalated layered lanthanum niobate KLaNb2O7. By the characterization of XRD, MnIIITMPyP cation is hypothesized to form an inclined monolayer between LaNb2O7−nanosheets. The as-prepared nanocomposite MnIIITMPyP-LaNb2O7has good electrocatalytic activities toward oxidation of nitrite. A linear range of 2 × 10−5∼ 2.14 × 10−2mol L−1with a detection limit of 1.3 × 10−5mol L−1is concluded by detection of amperometric response of the MnIIITMPyP-LaNb2O7modified electrode in nitrite solution, the mechanism of the nanocomposite toward electrocatalytic oxidation of nitrite is proposed.