Simple Solvothermal Synthesis Method Research Articles

Construction of Highly Luminescent Lanthanide Coordination Polymers and Their Visualization for Luminescence Sensing.

NaH2SIP was selected as an organic ligand (NaH2SIP = 5-sulfoisophthalic acid monosodium salt). We successfully constructed a new class of lanthanide coordination polymers Ln-HS ([Ln(SIP)(DMF)(H2O)4]DMF·H2O; Ln = Eu, Tb, Sm, and Dy) by a simple solvothermal synthesis method. They exhibited excellent photoluminescence properties for Ln3+ ions, where Eu-HS and Tb-HS exhibited high quantum yields of 13.70 and 42.38%, respectively. The codoped lanthanide coordination polymers obtained by doping with different ratios of Eu3+/Tb3+ serve as excellent ratiometric thermometers with high sensitivities in the physiological temperature range, with values of 16.8, 7.0, and 14.5%·K-1, respectively. The luminescent colors of Tb0.95Eu0.05-HS and Tb0.94Eu0.06-HS exhibit variations from green to yellow to orange, achieving visualized luminescence in a narrow temperature range. The composite film material Tb0.94Eu0.06-HS@PMMA demonstrates this color variation. Next, Tb0.5Sm0.5-HS obtained by Tb3+/Sm3+ codoping was investigated. The difference in the luminescence colors visible to the naked eye at different excitation wavelengths and the change in luminescence colors occur in a very narrow temperature range. All of them show the great value of the visualized luminescence in practical anticounterfeiting, with double anticounterfeiting function and high security.

Transition metal bismuth spheres dispersed and anchored in benzene-ring-grafted porous g-C3N4 nanosheets for photocatalytic reduction of CO2

Graphitic carbon nitride (g-C3N4) holds a prominent position in the field of photocatalysis and represents one of the most promising non-metallic catalysts at present. However, its inherent defects undermine its photocatalytic activity, thus limiting its practical applications. To address this issue, we employed transition metal bismuth spheres, which were dispersed and anchored on benzene-ring-grafted porous g-C3N4 nanosheets, for the photocatalytic reduction of CO2 via a simple solvothermal synthesis method. The experimental results revealed that Bi-BCN-0.2 exhibited the highest photocatalytic CO2 reduction, yielding 8.17 μmol/(g·h) of CO, which was 21 times greater than CN (0.39 μmol/(g·h)) and 8.5 times greater than BCN (0.95 μmol/(g·h)). Through relevant characterization, we found that the introduction of benzene rings in the CN skeleton resulted in an expansion of π-electron delocalization, leading to improved the efficiency of charge separation upon photoexcitation. Additionally, the further loading of Bi sphere co-catalysts, forming Schottky junctions, effectively inhibited the recombination of photogenerated electron-hole pairs and promoted photogenerated charge transfer. Furthermore, the SPR (surface plasmon resonance) effect enhanced the light harvesting ability. These modifications collectively contributed to enhancing the photocatalytic activity of g-C3N4 and introduced a novel approach for utilizing g-C3N4 in the photocatalytic reduction of CO2.

Facile synthesis of 2D Al-TCPP MOF nanosheets for efficient sonodynamic cancer therapy

2D Al-TCPP MOF nanosheets were preparedviaa simple solvothermal synthesis method without the need for any surfactants and were found to be an effective sonosensitizer for sonodynamic cancer therapy.

Universitetet i Oslo-67 (UiO-67)/graphite oxide composites with high capacities of toluene: Synthesis strategy and adsorption mechanism insight

In this paper, a simple solvothermal synthesis method was proposed for the preparation of metal organic framework/graphene oxide hybrid nanocomposite (UiO-67/GO). A series of UiO-67/GO composites were prepared by varying the addition forms and amounts of GO, and the optimal synthesis conditions were screened. The composites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission Electron Microscope (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS), water contact angles (CA) and thermogravimetric analysis (TGA). The adsorption capacity and the adsorption process of toluene were investigated by dynamic adsorption and adsorption kinetics, respectively. The results indicated that 67/GO-0.5% reached the maximum adsorption capacity (876 mg g−1), which far exceeded the other adsorbents. Kinetic model and the Weber-Morris model correlated satisfactorily to the experimental data. The improved adsorption performance was attributed to GO, which enhanced π-π interaction, promoted defect generation and provided more adsorption sites. Finally, the excellent regeneration performance of the adsorbent was verified by temperature programmed desorption (TPD) and cyclic adsorption–desorption experiments. Moreover, the adsorption mechanism was further revealed. Combined with the related adsorption experiments and the density functional theory (DFT) analysis, the efficient removal of toluene by UiO-67/GO was attributed to the cooperation of defects, π-π interaction and hydrogen bonding.

Integrating Covalent Organic Framework with Transition Metal Phosphide for Noble-Metal-Free Visible-Light-Driven Photocatalytic H2 Evolution.

2D covalent organic frameworks (COFs) are considered as one kind of the most promising crystalline porous materials for solar-driven hydrogen production. However, adding noble metal co-catalysts into the COFs-based photocatalytic system is always indispensable. Herein, through a simple solvothermal synthesis method, TpPa-1-COF, a typical 2D COF, which displays a wide light absorption region, is rationally combined with transition metal phosphides (TMPs) to fabricate three TMPs/TpPa-1-COF hybrid materials, named Ni12 P5 (Ni2 P or CoP)/TpPa-1-COF. The incorporated TMPs can be served as electron collectors for accelerating the transfer of charges on TpPa-1-COF, thus the composites are demonstrated to be efficient photocatalysts for promoting water splitting. Benefitting from the richer surface reactive sites and lower H* formation energy barrier, the Ni12 P5 can most effectively improve the photocatalytic performance of the TpPa-1-COF, and the H2 evolution rate can reach up to 31.6 µmol h-1 , approximately 19 times greater than pristine TpPa-1-COF (1.65 µmol h-1 ), and is comparable to the Pt/TpPa-1-COF (38.8 µmol h-1 ). This work is the first example of combining COFs with TMPs to construct efficient photocatalysts, which may offer new insight for constructing noble-metal-free COF-based photocatalysts.

Visible Light Hydrogen Production By CdZnS Photocatalysts Prepared in Ethylenediamine Aqueous Solution

Recently, semiconductor photocatalysts are expected to be a strategy to solve the energy demand and environmental pollution. Many researchers have attention, and have been developed photocatalysts for hydrogen production. Among them, metal sulfides (i.e. CdS, ZnS, MoS2, etc.), metal oxides (i.e. TiO2, Fe2O3, NiOx, RuO2) are regarded as good candidates for the photocatalytic H2 production. CdS is highly important as a photocatalyst because of the low band gap energy (~2.4 eV) and high activity under visible light irradiation for the photocatalytic hydrogen evolution reaction (HER) [1]. However, pure CdS tends to form particle aggregation and inherent photocorrosion, resulting in a higher recombination rate of charge carrier limited its application. One of the effective ways is by combing CdS with ZnS to form CdZnS (cadmium zinc sulfide) [2]. CdZnS has been regarded as a promising photocatalyst, but it has fast recombination of photogenerated electron-hole pairs. Therefore, the photocatalytic hydrogen evolution activity of sulfide semiconductor can be significantly improved by loading noble metals as cocatalysts to provide active sites for proton reduction.In this work, we report excellent H2 production performance when PdS, Pt are used as cocatalyst for CdxZn1-xS, which was synthesized via a simple solvothermal synthesis method. The resulting photocatalysts exhibit enhanced hydrogen production from water in 0.25 M Na2SO3 + 0.35 M Na2S as a sacrificial agent.The crystalline structures of as-prepared CdxZn1-xS were analyzed by XRD. The XRD peaks of Cd0.5Zn0.5S are weaker and broader than those of one prepared in the absence of ethylenediamine during the solvothermal synthesis. These results indicate that the addition of ethylenediamine has a certain inhibitory effect on the growth of the grain of Cd0.5Zn0.5S.Cd0.5Zn0.5S photocatalyst was selected as optimal one in this photocatalytic activity test. The photocatalytic H2 production over PdS deposited Cd0.5Zn0.5S was enhanced comparing that of pristine Cd0.5Zn0.5S, showing greater about two times. Further, in the presence of dual cocatalysts, namely PdS and Pt, the photocatalytic H2 production was about 2.4 times higher than that of pristine Cd0.5Zn0.5S. In summary, this work showed that CdxZn1-xS photocatalysts were synthesized successfully by a simple solvothermal method. With ethylenediamine in the solvothermal process, the crystallinity of CdxZn1-xS photocatalysts was lower than that of one prepared by the hydrothermal method. The use of dual co-catalysts, namely PdS and Pt, were effective for the photocatalytic H2 production under visible light.

Three-dimensional Ge/GeO2 shell-encapsulated Nb2O5 nanoparticle assemblies for high-performance lithium-ion battery anodes

We report an efficient nanostructure of three-dimensional germanium/germanium dioxide (Ge/GeO2) shell-encapsulated niobium pentoxide (Nb2O5) nanoparticle assemblies for high-performance Li storage anode materials. The Ge/GeO2-encapsulated Nb2O5 nanoassemblies are prepared via a simple solvothermal synthesis method. The Ge/GeO2 layer binds the surfaces and interfaces of the interconnected Nb2O5 nanoparticle assemblies, presenting as dense and uniform microspheres. The tightly bound Ge/GeO2 layer interconnects the nanoassemblies to provide high capacity and a pathway for Li+ and electron transport. Via the Nb2O5 assemblies, fast Li+ transport kinetics are secured using a pseudocapacitive reaction mechanism during Li insertion and extraction, while Ge nanoparticles provide the high specific capacity. As a result, the Ge/GeO2-encapsulated Nb2O5 microspheres deliver a greatly enhanced reversible capacity of 800 mA h g−1 and excellent high-rate capability. The superior high-performance in Ge/GeO2-encapsulated Nb2O5 microspheres arises from a synergetic effect between the interconnected microstructure and the highly reversible GeO2 phase. The encapsulated interconnection material design concept allows control of the Ge-based electrode materials composition making it ideal for fabrication of high-performance electrodes in Li-ion batteries.

Carbon nanodots anchored onto the metal-organic framework NH2-MIL-88B(Fe) as a novel visible light-driven photocatalyst: Photocatalytic performance and mechanism investigation

A one-pot strategy for the preparation of NH2-MIL-88B(Fe)/CDs composite was successfully developed via a simple solvothermal synthesis method. NH2-MIL-88B(Fe)/CDs composites were characterized by XRD, FT-IR, SEM, TEM, XPS, UV–vis DRS, PL, transient photocurrent response and Mott-Schottky plots. The synthesized NH2-MIL-88B(Fe)/CDs composites exhibit stronger photocatalytic activity than the original NH2-MIL-88B(Fe) in both photoreduction of Cr(VI) and photodegradation of MB. This is mainly because on the one hand, there is an interaction at the interface between CDs and NH2-MIL-88B(Fe), and on the other hand, CDs in the composite as local electron acceptors can effectively enhance charge transfer and inhibit electron-hole recombination. The experimental results show that the pH value greatly affects the reduction efficiency of Cr(VI) over photocatalyst, and the addition of hole trapping agent is beneficial to photocatalytic reduction. Moreover, we have proposed the possible photocatalytic mechanism on composites through trapping experiments of active species. Importantly, cycling experiments have also revealed that NH2-MIL-88B(Fe)/CDs photocatalysts have good chemical stability and reusability, and have broad industrial application prospects.

Spinel NiCo2O4 3-D nanoflowers supported on graphene nanosheets as efficient electrocatalyst for oxygen evolution reaction

Efficient oxygen evolution reaction (OER) electrocatalysts with non-noble metals are very critical for the large-scale exploitation of electrocatalytic hydrogen production systems. To improve the catalytic activity of OER electrocatalysts, several design strategies, such as construction of nanostructures, porous structures and composite materials have been proposed. Herein, spinel NiCo2O4 3-D nanoflowers supported on graphene nanosheets (GNs) are prepared by a simple solvothermal synthesis method as non-noble metal electrocatalysts for OER. The present NiCo2O4/GNs composite integrates multiple advantages of nanostructures, porous structures and composite materials, including high surface area, abundant catalytic sites and high stability. Benefiting from the favorable features, the NiCo2O4/GNs composite exhibits a better OER performance than NiCo2O4 and RuO2 in alkaline medium, which has a low onset potential (1.50 V), a small Tafel slope (137 mV dec−1). The present work opens a new window for the construction of the carbon-supported 3-D nanostructure of transition metal catalysts with optimizable electrocatalytic performances for electrocatalytic hydrogen production.

Cs2.5H0.5PW12O40 Encapsulated in Metal–Organic Framework UiO-66 as Heterogeneous Catalysts for Acidolysis of Soybean Oil

The Keggin-type Cs2.5H0.5PW12O40 was encapsulated in metal–organic framework UiO-66 by a simple solvothermal synthesis method. The characterization results showed that the morphology and crystal structure of UiO-66 were preserved, and the heteropolyanion structure remained unchanged after Cs2.5H0.5PW12O40 encapsulation. The prepared Cs2.5H0.5PW12O40@UiO-66 material has demonstrated to be an environmentally benign catalyst in the acidolysis of soybean oil with medium-chain fatty acids for the production of low-calorie structured lipids. The FT-IR CO adsorption experiments revealed that additional Lewis acid sites were formed in the solid acid catalyst, which were essential to catalyze the acidolysis reaction. The solid catalyst could be reused for several recycles without obvious deactivation due to hardly leaching of active components into the reaction mixture.

Controlled fabrication of Sn/TiO2 nanorods for photoelectrochemical water splitting

In this work, we investigate the controlled fabrication of Sn-doped TiO2 nanorods (Sn/TiO2 NRs) for photoelectrochemical water splitting. Sn is incorporated into the rutile TiO2 nanorods with Sn/Ti molar ratios ranging from 0% to 3% by a simple solvothermal synthesis method. The obtained Sn/TiO2 NRs are single crystalline with a rutile structure. The concentration of Sn in the final nanorods can be well controlled by adjusting the molar ratio of the precursors. Photoelectrochemical experiments are conducted to explore the photocatalytic activity of Sn/TiO2 NRs with different doping levels. Under the illumination of solar simulator with the light intensity of 100 mW/cm2, our measurements reveal that the photocurrent increases with increasing doping level and reaches the maximum value of 1.01 mA/cm2 at −0.4 V versus Ag/AgCl, which corresponds to up to about 50% enhancement compared with the pristine TiO2 NRs. The Mott-Schottky plots indicate that incorporation of Sn into TiO2 nanorod can significantly increase the charge carrier density, leading to enhanced conductivity of the nanorod. Furthermore, we demonstrate that Sn/TiO2 NRs can be a promising candidate for photoanode in photoelectrochemical water splitting because of their excellent chemical stability.

Solvothermal Growth of Cobalt Oxide Hexagon Nanodiscs

In this work, cobalt oxide nanodiscs were successfully fabricated through a simple solvothermal synthesis method. The obtained cobalt hydroxide nanodiscs are of single-crystalline hexagonal structure with well-defed nanodiscs were found to have very weak magnetic properties, much weaker than its bulk cobalt oxide counterparts, which might find interesting application in special electromagnetism devices.

Nitrogen-doped In2O3 nanocrystals constituting hierarchical structures with enhanced gas-sensing properties

Doping indium oxide with nitrogen species is a strategy to extend its photoresponse to the visible region and to modify its band structure, enabling the material to have potential applications in photocatalysis, optoelectronics, and sensors. In this paper, we report on a simple solvothermal synthesis method for producing nitrogen-doped indium oxide nanocrystals that are composed of hierarchical structures. The samples were characterized with XRD, Raman spectroscopy, SEM, HRTEM, FTIR, XPS, UV-vis, and photoluminescence techniques, and further tested in the role of an ethanol gas sensing material. The optical properties and the gas-sensing performance of indium oxide can be tuned by controlling the nitrogen doping. Also, the nitrogen species, resulting from the nitrogen doping, function like a surface modifier to enhance the sensitivity of the sensors that were made from the nitrogen-doped indium oxides on their exposure to ethanol gas.