One-pot Solvothermal Route Research Articles

One-pot solvothermal route to stannite-like Cu2CoSnS4 microspheres as pseudocapacitive material for electrochemical energy storage

This study explores the potential of stannite-like Cu2CoSnS4 (CCTS) microspheres for electrochemical energy storage applications. To fabricate Cu2CoSnS4, a facile solvothermal route was employed using ethylene glycol (EG) as the solvent and polyvinyl pyrrolidone (PVP) as the capping and structure-directing agent. Thorough characterization techniques, including X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray analysis, and electron microscopy were employed to investigate the crystallinity, morphology, lattice structure, and growth mechanism of CCTS microspheres. UV–vis–NIR spectroscopy revealed that the material exhibits absorption in the visible and near-infrared range, with an optimal bandgap of 1.4 eV, suggesting potential applications in photovoltaics. We also analyzed the disordered stannite structure by a combined study of Raman spectroscopy and elemental analysis. Furthermore, the prepared CCTS microspheres were tested as active materials of supercapacitor electrodes, and the results showed promising electrochemical performance with a specific capacitance of 1700 F g−1 at 5 mV s−1, which is close to 70 % of the theoretical specific capacitance of Cu2CoSnS4. The electrode maintained 80.2 % capacitance retention and a Coulombic efficiency of 99.8 % after 500 cycles. This research highlights CCTS microspheres as promising candidates for energy harvesting and storage applications.

Facile construction of MoS2 decorated CdS hybrid heterojunction with enhanced hydrogen generation performance

Promoting the charge separation to improve photocatalytic performance of semiconductor photocatalysts is very important in the field of artificial photosynthesis. Here, a novel MoS2/CdS 2D–2D ultrathin nanosheet heterostructure was fabricated via a one-pot solvothermal route. The obtained 2D–2D MoS2/CdS nanojunction has not only provided large contact areas, but also shortened the charge transport distance, resulting in significantly enhanced photocatalytic H2 evolution property. The composites that were synthesized were examined using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Transmission electron microscope (TEM), UV-vis diffuse reflectance spectra (DRS), Photoluminescence (PL) and X-ray photoelectron spectra (XPS) analysis. By optimizing the 2D MoS2 amounts in the heterojunction, the 5 wt.% 2D/2D MoS2/CdS heterojunction displayed the maximal photocatalytic H2 evolution rate of 4449 μmolh−1g−1 under visible light irradiation in the presence of lactic acid as the sacrificial reagent, which was 6 times higher than that of pristine 2D CdS. Based on the photoelectrochemical and photoluminescence spectra tests, it could be deduced that the charge separation and transfer of 2D/2D MoS2/CdS heterojunction was tremendously improved, and the recombination of photoinduced electron-hole pairs was effectively impeded. Moreover, the 2D MoS2 was used as a cocatalyst to provide the abundant active sites and lower the overpotential for H2 generation reaction. The current work would offer an insight to fabricate the 2D/2D heterojunction photocatalysts for splitting H2O into H2.

Spatially confined synthesis of TiNb2O7 quantum dots onto mesoporous carbon and Ti3C2TX MXene for boosting lithium storage

TiNb2O7 has been emerged as one of the most promising electrode materials for high-energy lithium-ion batteries. However, limited by the slow electron/ion transport kinetics, and insufficient active sites in the bulk structure, the TiNb2O7 electrode still suffers from unsatisfactory lithium storage performance. Herein, we demonstrate a spatially confined strategy toward a novel TiNb2O7-NMC/MXene composite through a triblock copolymer-directed one-pot solvothermal route, where TiNb2O7 quantum dots with a particle size of 2–3 nm are evenly embedded into N-doped mesoporous carbon (NMC) and Ti3C2TX MXene. Impressively, the as-prepared TiNb2O7-NMC/MXene anode exhibits a high reversible capacity (486.2 mAh g−1 at 0.1 A g−1 after 100 cycles) and long cycle lifespan (363.4 mAh g−1 at ss1 A g−1 after 500 cycles). Both experimental and theorical results further demonstrate that such a superior lithium storage performance is mainly ascribed to the synergistic effect among 0D TiNb2O7 quantum dots, 2D Ti3C2TX MXene nanosheets, and N-doped mesoporous carbon. The strategy presented also opens up new horizon for space-confined preparation of high-performance electrode materials.

One-Pot Solvothermal Synthetic Route of a Zinc Oxide Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite: An Advanced Material with a Novel Anticancer Theranostic Approach.

This study focuses on a one-pot solvothermal synthetic route for the preparation of uniformly decorated zinc oxide nanoparticles on the surface of reduced graphene oxide (rGO/ZnO-NC) by using Andrographis paniculata leaf aqueous extract as an eco-friendly reducing agent. After characterizing the samples by different physical and chemical techniques, the anticancer activity of the synthesized rGO/ZnO-NC was examined on two human cancerous cell lines (HCT116 and A549) and one normal cell line (hMSCs). The MTT assays revealed that rGO/ZnO-NC exhibited dose-dependent cytotoxicity at a maximum concentration range of 10 ppm and the viability of the cells was drastically decreased to 95-96%. Measurement of reactive oxygen species (ROS) generation and Annexin V-FTIC staining assay revealed that rGO/ZnO-NC induced apoptosis in HCT116 and A549 cell lines. Thus, this study shows that the green-synthesized rGO/ZnO-NC has great potential in developing an efficacious novel therapeutic agent for cancers.

Defect engineered 2D mesoporous Mo-Co-O nanosheets with crystalline-amorphous composite structure for efficient oxygen evolution

Two-dimensional (2D) mesoporous metal-oxide (hydroxide) nanomaterials with defects are promising towards the realization of efficient electrocatalysis. Herein, we report a facile and effective one-pot solvothermal route to synthesize mesoporous Mox-Co-O hybrid nanosheets (NSs) which is composed of crystalline Mo4O11 and amorphous cobalt hydroxide. Due to the corrosion of 1-octylamine at high temperatures, abundant mesoporous holes are created in situ over the Mox-Co-O hybrid NSs during the solvothermal process, which is beneficial to increasing the electrochemical surface area. The dimension of the Mox-Co-O NSs, size of mesoporous and the concentration of defects can be easily modulated by controlling the molar ratio of Mo/Co. Electrochemical measurements reveal that the 2D mesoporous Mox-Co-O NSs show an excellent activity for the oxygen evolution reaction with the highest catalytic activity of η10 = 276 mV at 10 mA cm−2 in 1 mol L−1 KOH. Enhanced adsorption of intermediates and abundant oxygen vacancies achieved by appropriate Mo doping are the two main factors that contribute to the excellent catalytic activity of Mo0.2-Co-O NSs. This work, with the construction of 2D metal-oxide (hydroxide) crystalline-amorphous nanomaterials possessing abundant holes, oxygen vacancies and enhanced adsorption of intermediates, provides important insight on the design of more efficient catalysts.

Carboxylic functionalized mesoporous polymers for fast, highly efficient, selective and reversible adsorption of ammonia

Developing an effective method for separation of NH3 from N2, H2 and CO2 is highly desired not only for the advancement of Haber-Bosch process, but also for protection of the environment. Here, we report synthesis of carboxylic functionalized mesoporous polymers by copolymerization of divinylbenzene (DVB) and acrylic acid (AA) through a one-pot solvothermal route. The mesoporous structure and acidic site concentration of these polymers can be adjusted by changing the amounts of monomers used. Such polymers display fast, highly efficient and selective adsorption of NH3 that is better than that of most other solid sorbents in the literature, especially in terms of NH3 adsorption selectivity against N2, H2 and CO2. The adsorption of NH3 by these polymers is also highly reversible, making them promising solid sorbents for production of high-purity NH3.

Striking dual functionality of iron pyrite-graphene oxide nanocomposites in water treating and water splitting reactions

In this study, we report a simple one-pot solvothermal route of FeS2 (pyrite)/GO (graphene oxide) nanocomposites that exhibit outstanding physicochemical properties as efficient catalysts towards dual functionality of water treating and water-splitting applications. The FeS2/GO (FSG) nanocomposites of varying FeS2 to GO weight ratios were prepared and characterized for physicochemical properties. The introduction of GO mediated the morphology and structural properties to aligned FeS2 spherical nanoparticles within the GO network compared with pristine FeS2 cubical nanostructures. In water treatment applications, the synthesized FSG nanocomposite with FeS2 to GO ratio of 4:3 was highly effective for the complete degradation (∼99%), significant mineralization (>70%), and complete detoxification of antibiotic amoxicillin (AMCT) under the optimal solar-Fenton treatment when compared to bare FeS2, and other FSG nanocomposites. Radical scavenging experiments, leaching profile for iron (Fe) species (total Fe, Fe(II), and Fe(III)), decomposition profile of hydrogen peroxide, and HO• generation in the reaction medium helps to postulate the possible reaction mechanisms for AMCT degradation. The greatly enhanced catalytic performance of FeS2/GO was correlated with efficient recycling of Fe(II)/Fe(III), higher solar-light absorptivity due to the GO existence, and synergistic coupling of FeS2 and GO evidenced through the strong formation of Fe-O chemical bonds as confirmed by Fourier-transform infrared spectroscopy. Finally, the nanocomposites achieved enhanced apparent quantum efficiency for hydrogen generation through a water-splitting reaction. The reaction mechanism of FSG nanocomposite for water-splitting was proposed accordingly. Overall, this work could provide new insights for developing potential nanocomposite materials for widespread energy generation and environmental remediation applications.

Novel Insights into Sb-Cu Catalysts for Electrochemical Reduction of CO2

Catalysts play a vital role in electrochemical reduction of CO2 to valuable products. Only based on effective catalysts, CO2 electrolysis process can be advanced toward industrial application. In this work, we present a Sb-Cu2O material synthesized via one-pot microwave-assisted solvothermal route. The Sb-Cu2O derived bimetallic catalyst achieves a highest CO selectivity of 96% and good CO partial current densities of 37.3 and 74.0 mA cm−2 at − 0.8 and − 1.2 V vs. reversible hydrogen electrode (RHE), respectively. The Sb-Cu catalyst also displays good stability at current densities ranging from 5.6 to 100 mA cm−2. Additionally, for the first time, a complete theoretical study reveals the critical roles of Sb in selective CO2 conversion to CO on this bimetallic material, including stabilizing stepped Cu surfaces selective for the reaction, lowering energy barriers for the formation of key intermediate and favouring CO desorption.

Highly fluorescent green and red emissions from boron-doped graphene quantum dots under blue light illumination

Highly fluorescent boron-doped graphene quantum dots (B-doped GQDs, average particle size of ∼4 nm) are synthesized via one-pot solvothermal route in the presence of 1,3,6-trinitropyrene (TNP) and boric acid. The chemical ratio of the boric acid to TNP precursor is identified as a crucial factor in modulating the B-dopant concentration within the GQD lattices. The GQD suspensions maintain uniform dispersion over extended operation thanks to the NO2 groups formed in the GQD edge sites promoting high dispersivity in polar and nonpolar solvents. The B-doped GQD suspensions are homogeneously stored in n-hexane and propylene glycol methyl ether acetate, enabling highly fluorescent green and red emission, respectively. Under the blue-light illumination, the green emission takes place at ca. 541 nm with a narrow full width at half maximum (FWHM) of 31.7 nm, whereas the red emission centers at ca. 617 nm with a FWHM of 42.5 nm. Through adjusting the concentration of B-dopant, the quantum yield of green and red fluorescence reached as high as 99.8 and 17.1%, respectively. Accordingly, the novel solvothermal synthesis route developed in this work provides the essential framework for engineering B-doped GQDs with tunable optical properties for high-performance biosensors and biomedical devices.

PdAg Nanoparticles with Different Sizes: Facile One-Step Synthesis and High Electrocatalytic Activity for Formic Acid Oxidation.

Recently, direct formic acid fuel cells (DFAFCs) which possess superior advantages such as a low operating temperature, light environmental pollution and high energy density, have been considered as one of the power generation technologies with a bright prospect. Herein, bimetallic PdAg nanoparticles (NPs) with different particle sizes were successfully produced via an easy one-pot solvothermal co-reduction synthetic route and their electrocatalytic performance for formic acid oxidation (FAO) were further investigated. In our strategy, the size of PdAg NPs can be easily controlled by only varying the concentration of precursors. The larger sized PdAg alloy (9.5 nm, noted as PdAg-L) was obtained at a low concentration of precursors, while the smaller PdAg alloy (3.7 nm, named as PdAg-S) was separated from the reaction system with higher solubility by centrifugation. The electrocatalytic activity and stability of the obtained PdAg NPs could be well optimized when incorporated with carbon (C), which is owing to a synergetic effect. The PdAg-S/C exhibits the highest mass activity with around 1.6 times that of PdAg-L/C and 2 times that of commercial Pd/C, which can be attributed to its larger ECSA and lower adsorption energy of the intermediate to facilitate the direct oxidation of HCOOH molecule.

Enhanced photocatalytic properties of Mn doped CdS catalysts by decomposition of complex precursors

Photocatalysts of one-dimensional (1D) Mn x Cd 1-x S nanorods (NRs) were synthesized by decomposing complex precursors. The photocatalytic experiments confirmed that Mn x Cd 1-x S samples presented an enhanced photocatalytic property due to Mn 2+ doping. The optimal Mn 2+ concentration of x = 0.02 showed the highest photocatalytic performance. Moreover, the Mn 0.02 Cd 0.98 S sample had a universal and stable photocatalytic property in the visible light range. We attributed the enhanced photocatalytic activity to the shallow trapping sites and the narrow energy band gap derived from the appropriate Mn 2+ doping, which promote efficient charge separation. • Mn x Cd 1-x S NRs were fabricated by one-pot solvothermal route. • Mn 0.02 Cd 0.98 S NRs exhibited excellent photocatalytic activity and durability. • O 2 . • − was the dominant reactive species for the degradation of RhB dye. • The enhanced activity is due to shallow trapping sites and bandgap narrowing.

Synthesis of PEGylated BaGdF5 Nanoparticles as Efficient CT/MRI Dual-modal Contrast Agents for Gastrointestinal Tract Imaging

Molecular imaging (MI) techniques have extremely significant effect on the diagnosis and prognosis of diseases, such as gastrointestinal (GI) tract-related diseases. Furthermore, nanomaterials as contrast agents have attracted a great deal of research attention, due to their rational fabrication and biomedical. Herein, we reported a facile process to synthesis PEGylated BaGdF5 nanoparticles via a one-pot solvothermal route as CT/MRI dual-modal contrast agents for in vivo imaging of GI tract. Compared to the commercially used iodine contrast agents, the well-prepared nanoparticles exhibited enhancement in computed tomography (CT) imaging. In the presence of Gd, nanoparticles could also be used in magnetic resonance imaging (MRI). PEGylated BaGdF5 nanoparticles were characterized by transmission electron microscopy (TEM), X-ray powder diffraction analysis (XRD), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). Besides, MTT assay revealed that the prepared nanoparticles proved to be low toxicity and high biocompatibility for Hela cells. Hemolytic assay illustrated nanoparticles possess favorable hemocompatibility. H & E (Hematoxylin and Eosin) histological staining assessed long-term toxicity of oral PEGylated BaGdF5 nanoparticles, and the results showed that the nanoparticles had overall safety for GI tissue with comparatively high compatibility. Based on above results, PEGylated BaGdF5 nanoparticles were admired multi-functional contrast agents to apply in CT and MRI imaging with prominent prospects.

Carbon-Coated Superparamagnetic Nanoflowers for Biosensors Based on Lateral Flow Immunoassays.

Superparamagnetic iron oxide nanoflowers coated by a black carbon layer (Fe3O4@C) were studied as labels in lateral flow immunoassays. They were synthesized by a one-pot solvothermal route, and they were characterized (size, morphology, chemical composition, and magnetic properties). They consist of several superparamagnetic cores embedded in a carbon coating holding carboxylic groups adequate for bioconjugation. Their multi-core structure is especially efficient for magnetic separation while keeping suitable magnetic properties and appropriate size for immunoassay reporters. Their functionality was tested with a model system based on the biotin–neutravidin interaction. For this, the nanoparticles were conjugated to neutravidin using the carbodiimide chemistry, and the lateral flow immunoassay was carried out with a biotin test line. Quantification was achieved with both an inductive magnetic sensor and a reflectance reader. In order to further investigate the quantifying capacity of the Fe3O4@C nanoflowers, the magnetic lateral flow immunoassay was tested as a detection system for extracellular vesicles (EVs), a novel source of biomarkers with interest for liquid biopsy. A clear correlation between the extracellular vesicle concentration and the signal proved the potential of the nanoflowers as quantifying labels. The limit of detection in a rapid test for EVs was lower than the values reported before for other magnetic nanoparticle labels in the working range 0–3 × 107 EVs/μL. The method showed a reproducibility (RSD) of 3% (n = 3). The lateral flow immunoassay (LFIA) rapid test developed in this work yielded to satisfactory results for EVs quantification by using a precipitation kit and also directly in plasma samples. Besides, these Fe3O4@C nanoparticles are easy to concentrate by means of a magnet, and this feature makes them promising candidates to further reduce the limit of detection.

Flower-like Bi2SiO5/Bi4MoO9 heterostructures for enhanced photocatalytic degradation of ciprofloxacin

Bi2SiO5/Bi4MoO9 photocatalysts with heterostructures were successfully prepared using a one-pot solvothermal route. The effect of the molybdenum source on composite formation is discussed. Under ultraviolet light irradiation, the Bi2SiO5/Bi4MoO9 heterojunction photocatalyst exhibited higher photocatalytic performance than Bi2SiO5 and Bi4MoO9 towards the degradation of ciprofloxacin (CIP). This dramatically enhanced photoactivity can be ascribed to the construction of a heterojunction interface between Bi2SiO5 and Bi4MoO9, which not only suppresses the recombination of photoexcited charge carriers but also enhances light absorption. In addition, from a practical point of view, the the effect of initial CIP concentration and coexisting ions on the photodegradation process using as-prepared Bi2SiO5/Bi4MoO9 heterojunction photocatalysts was explored. Trapping experiments demonstrate that photoexcited holesand superoxide radicals are the main active species in the photodegradation of CIP over Bi2SiO5/Bi4MoO9 heterojunctions. Meanwhile, the conduction band and valence band potentials of Bi2SiO5 and Bi4MoO9 were measured by density functional theory calculation, diffuse reflectance spectroscopy and Mott–Schottky curves. A possible photocatalytic mechanism for CIP degradation over the Bi2SiO5/Bi4MoO9 heterojunction is proposed.

Controllable fabrication of visible-light-driven CoSx/CdS photocatalysts with direct Z-scheme heterojunctions for photocatalytic Cr(VI) reduction with high efficiency

Visible-light-driven and ultra-stable CoSx/CdS photocatalysts were controllably fabricated by the ZIF-67-templated one-pot solvothermal route for highly efficient photocatalytic Cr(VI) reduction. It was discovered that the resulting CoSx/CdS composites could present different photocatalytic activities controllably depending on the CoSx-to-CdS molar ratios used. The one with 1/16 M ratio could display the highest photocatalytic reduction performance for Cr(VI) with the efficiency up to 100% within 30 min, which is 5.6-fold and 2.1-fold higher than that of pristine CoSx and CdS, respectively. Herein, the components of CoSx and CdS with well-matched energy-band structures might serve separately as the electrons donor and the holes quencher to prolong the lifetime of photogenerated electrons in CoSx/CdS composites. A direct Z-scheme heterojunction could be thus constructed for promoting the charge carrier transferring with the improved redox abilities, leading to the robust photocatalysis of CoSx/CdS photocatalyst. Moreover, the developed CoSx/CdS photocatalyst could present superior stability with the structure and activity well survived after five photocatalytic cycles. This work may pave the way towards the controllable construction of a direct Z-scheme photocatalytic system by synergistically combining two kinds of components with matched energy-band structures, achieving the enhanced photocatalysis for the wide applications in the environmental remediation field.

Facile synthesis and extended visible light activity of oxygen and sulphur co-doped carbon nitride quantum dots modified Bi2MoO6 for phenol degradation

A novel one-pot solvothermal route was employed to construct O and S co-doped graphitic carbon nitride quantum dots (OSCNQDs) hybridized with Bi2MoO6 (BMO) photocatalyst and utilized to catalyse aqueous phenol from simulated wastewater under extended visible light exposure. The photodegradation analysis depicted that the (OSCNQDs/BMO) nanohybrid exhibited incremented photocatalysis of phenol (98 %) under visible light illumination which is due to the effective coupling and formation of Z-scheme heterostructure which rendered superior space isolation and retained high redox abilities. The OSCNQDs might contribute to the extended absorption of visible light as well as increased adsorption of phenol on the surface of photocatalyst. As a result, the nanohybrid displayed prominent absorption in visible region, improved space charge isolation and superior photoactivity which can be utilized as an effective approach for the photo-assisted degradation of organic pollutants.

Novel Magnetically Hollowsphere Zn-Doped Magnetite for the Efficient Photo-Reduction of Cr(VI)

Uniform and magnetic recyclable hollowsphere Zn doped Fe3O4 were successfully synthesized via simple one-pot solvothermal route. Morphology and structure of as-obtained products was characterized by XRD, SEM, HRTEM methods. The Zn-doped Fe3O4 hollowsphere exhibited high photocatalytic activity for degradation of hexavalent chromium under visible light irradiation. The effects of reaction conditions such as initial pH, photocatalyst dosage and hexavalent chromium contratentation were also studied systematically. The stability of the catalysts and and possible catalytic mechanism was also proposed. The results indicate that Zn doped Fe3O4 can be promising catalyst for photo-reduction of hexavalent chromium.

Direct Z-scheme photocatalyst of hollow CoSx@CdS polyhedron constructed by ZIF-67-templated one-pot solvothermal route: A signal-on photoelectrochemical sensor for mercury (II)

A visible-light-driven photoelectrochemical (PEC) sensor has been developed for probing Hg2+ with “turn-on” signal output using hollow CoSx@CdS polyhedron as direct Z-scheme photocatalyst and Hg2+-recognition probe. The CoSx@CdS heterojunction photocatalysts were fabricated by growing CdS nanoparticles on the surface of cobalt sulfide (CoSx) via one-pot solvothermal route using metal-organic frameworks (MOFs) of ZIF-67 polyhedrons as the sacrificial templates and cobalt precursors. It was discovered that the photocurrent responses of the CoSx@CdS-modified ITO electrodes could be specifically turned on by Hg2+, in contrast to these of the CoSx or CdS-modified ones showing no significant Hg2+-induced photocurrent. Under visible light irradiation, herein, the synergetic combination of CoSx and CdS components could improve the carriers transferring of PEC system. More importantly, the photocurrents of the PEC sensor could be greatly enhanced in the presence of Hg2+ through the selective ion-exchange reaction to trigger the in-situ formation of a new Z-scheme heterojunction of CoSx@CdS/HgS photocatalysts, achieving the further promoted charge transferring and suppressed recombination of photogenerated electron-hole pairs. The developed double heterojunctions-based PEC sensors can detect Hg2+ with the concentrations ranging from 0.010 to 1000 nM, which performances are much better than those of the current PEC analysis methods. Besides, such a MOF-templated one-pot construction route may pave the way toward the design of various direct Z-scheme heterojunction photocatalysts of PEC probes of great interest.

In Situ Crystallization of Active NiOOH/CoOOH Heterostructures with Hydroxide Ion Adsorption Sites on Velutipes-like CoSe/NiSe Nanorods as Catalysts for Oxygen Evolution and Cocatalysts for Methanol Oxidation.

Hydroxide ion (OH-) adsorption process is critical for accelerating the half-reactions of both metal-air batteries and direct methanol fuel cells in alkaline media. This study designs a rational catalyst/cocatalyst by constructing the readily available OH-adsorption sites to boost oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). Cobalt selenide-coated nickel selenide nanorods are in situ grown on nickel foam to obtain CoSe/NiSe-nrs/NF via a one-pot solvothermal synthesis route. CoSe-0.2/NiSe-nrs/NF (Co/Ni molar ratio of 0.26) exhibits an excellent OER activity(an overpotential of 310 mV at 100 mA cm-2 and a Tafel slope of 58.3 mV dec-1). The differently oriented CoSe/NiSe-nrs with a velutipes-like structure and metallic property provide a promising electrical conductivity for charge transfer. In situ X-ray diffraction tests verify the crystallization of active β-NiOOH during OER, and the crystallized NiOOH/CoOOH contributes to the excellent OER cycling stability in alkaline media. Synergistic effects between CoSe and NiSe-nrs/NF can balance the formation of NiOOH/CoOOH heterostructures to govern the exposure of available active sites. NiOOH/CoOOH as a highly active component can energetically adsorb OH- to promote OER. CoSe/NiSe-nrs/NFs as a low Pt-loading (0.5 wt%) support offer the mutually beneficial interactions for promoting cocatalytic and COads (poisonous intermediate) co-oxidation activities toward MOR. The electrochemically active surface area and mass activity of Pt/CoSe-0.2/NiSe-nrs/NF are 85 m2 gpt-1 and 1437.1 mA mgpt-1, respectively, which are much higher than those of commercial Pt/C (10.0 wt%). OH- absorbed on the NiOOH/CoOOH structure eliminates COads on the Pt surface via bifunctional mechanisms to improve the MOR activity. This study provides a promising reference for designing the versatile catalysts for energy conversion.

Ultrathin molybdenum disulfide nanosheet-coated acetylene black: One-pot synthesis and electrocatalytic hydrogen evolution

Molybdenum disulfide (MoS2) and its composites are the promising electrocatalysts for the hydrogen evolution reaction (HER) in acidic solution because it is earth-abundant and low-cost. Here we reported the ultrathin molybdenum disulfide nanosheet-coated acetylene black (AB) coated (MoS2@AB) as the electrocatalysts for the HER. The catalysts were synthesized in a facile one-pot solvothermal route. The as-prepared catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM, X-Ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The results show that the MoS2 nanosheets on AB have a few layers and many surface defects, which are benefical to the HER catalysis. Electrochemical tests revealed that the existence of AB can't only make the catalyst expose a considerable amount of active sites but also increase the turnover frequency (TOF) value per site. In addition, the MoS2@AB(75) had excellent electro-catalytic HER performances with a low onset potential (−110 mV), a small Tafel slope (50–60 mV per decade) and the longtime stability (10 h).