Highly photoluminescent single-layer graphene quantum dots around Au nanocubes (SLGQDs/Au) were synthesized using a simple method. The SLGQDs were synthesized using a low-cost hydrothermal method from glucose as a precursor. The atomic force microscopy analysis proved that the average thickness of the GQDs is lower than 4 ?, meaning that the GQDs are single-layer dots. The novel cubic shape of the SLGQDs/Au nanocomposites was confirmed by field-emission scanning electron microscopy and Transmission electron microscopy. Structural characterization was performed by X-ray diffraction, energy-dispersive X-ray spectroscopy and Raman spectroscopy. Photoluminescence (PL) spectroscopy revealed that the obtained SLGQDs/Au nanocomposite has a higher

Highly porous films of TiO 2 nanoparticles were prepared by a doctor blade method using carbon nanospheres as a porosity enhancer. At first, carbon nanospheres with a diameter ranging from 100 to 600 nm were synthesized by a hydrothermal method; then, a paste of TiO 2 nanoparticles was mixed with various amounts of carbon nanospheres. To obtain a porous TiO 2 nanoparticles photoanode and removing carbon nanospheres, photoanode was sintered at a temperature of 500 C. XRD patterns and Raman analysis revealed the anatase phase of TiO 2 and show that the carbon spheres acted only as a porosity enhancer. Removing carbon nanospheres leads to the creation of cavities with various sizes in dye-sensitized solar cells (DSSCs). Under illumination, the

Sluggish kinetics is the major obstruction in the reaction of water splitting. Design and development of noble metal-free, active and bifunctional electrocatalysts are crucial for the oxygen evolution reaction (OER). Transition-metal selenides have been applied as OER catalyst alternatives to noble metal-based catalysts. Herein, we report that a Fe-doped Ni3Se2 film electrodeposited on a conductive three dimensional macro-porous Ni foam (NF) substrate behaves as a robust electrocatalyst for the OER in a strongly basic medium (1 M, KOH), showing good activity compared to its un-doped counterpart. This catalyst showed excellent performance, exhibiting a current density of 10 mA cm−2 at an overpotential of 225 mV and a low Tafel slope (35.3

Low cost, gram scale and highly N doped graphene quantum dots (NGQDs) with a broad absorption spectrum was synthesized using hydrothermal method by citric acid and urea. The obtained NGQDs possess wide absorption spectrum from ultraviolet to visible and IR range of wavelength. Optical characterization revealed that NGQDs are highly photoluminescent in three region of light (i.e. UV, Vis and IR). The average thickness is lower than 1 nm, meaning that the NGQDs are single, two or three layers of graphene. Lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the NGQDs determined using a cyclic voltammetry (CV) method, and energy band gap was obtained ∼ 1.91 eV. A mechanism of charge carrier generati

The production of hydrogen by water electrolysis fundamentally requires growth of strong and effective oxygen evolutional electrocatalysts. Transition metal selenides, comprising of earth abundant elements have attracted regards as superb electrocatalysts for oxygen evolution reaction (OER) in the alkaline electrolyte. Toward defeat the huge overpotential for OER, in this manuscript we investigate the expansion of Fe doped cobalt-diselenide (Fe-CoSe2) nanostructure over 3D nickel foam (NF) through a simple and scalable electrodeposition technique. The prepared Fe-CoSe2/NF electrode demands an overpotential of only 220 and 256?mV to attain the current density of 10 and 100?mA?cm−2, respectively. Moreover, the Fe-CoSe2/NF exhibits negligibl

Highly active anemone-like MoS2 catalyst was vertically and directly deposited on fluorine-doped tin oxide (FTO) substrate via a straightforward facile hydrothermal method with excellent adhesion and appreciable stability for hydrogen evolution reaction (HER). MoS2 catalyst with unique morphology full of active edge sites and surface areas was fabricated by varying synthesis time and specific concentration of precursors. Structural characteristics were investigated by X-ray diffraction pattern (XRD), and Raman spectroscopy. Field emission scanning electron microscopy (FESEM) images show the variation of morphology during synthesis time as a very important factor in the preparation process. It also reveals the lamellar structure of anemone-l

Carbon spheres with controllable structures (i.e., nano and microstructure)were prepared by using a hydrothermal method. By adjusting the concentration ofglucose solution at a both constant temperature and constant process time in a sealedautoclave, the total size of carbon spheres (CSs) was changed from nano to microscale.Then micronanobinary carbon spheres structure (MNCS) was successfully obtained bycoating colloidal solution of carbon nanospheres (CNSs, average diameter of 186 nm)and microspheres (CMSs, average diameter of 5 μm) on the FTO substrates. It wasrealized that by annealing of the carbon spheres under vacuum condition, theirfunctional groups were reduced, therefore, this effected on the wetting behavior ofcarbon spheres. The

A novel nebulizing spray hydrolysis approach was used for preparation of semi-transparent superhydrophobic coatings. Methyltrimethoxysilane was dissolved in water:ethanol mixture and ultrasonically sprayed on different substrates. Superhydrophobic coatings with a contact angle (CA) as high as 164? and a sliding angle below 5? were obtained. FESEM and AFM revealed a hierarchical micro-nano binary structure with nanometric roughness of the coatings. The coated glass substrate exhibited transmittance close to 80%. The prepared coating showed great self-cleaning and water jet repellency behaviors. The superhydrophobicity of the samples was remained after subjecting to ambient conditions for 50 days. The coating was also durable under water flus

Ultrathin sheets of transition metal dichalcogenides have received a great deal of interest in an attempt to develop advanced electrode nanomaterials for electrochemical capacitors, with most of the attention focused on pure transition metal dichalcogenides. We systematically investigated and compared the charge storage capability of tert-butyllithium-exfoliated group 6 transition metal dichalcogenide materials (MX2; M?=?Mo, W; X?=?S, Se, Te). The group 6 MX2 2D materials exhibited distinctive charge storage performance as a result of their different chemical compositions and morphological features. MoTe2 nanosheets demonstrated the highest gravimetric capacitance of all materials. Furthermore, we hybridized these 2D materials with nanofibr

The bulk oxygen vacancy formation, migration energy and surface migration energy of BSFCu and BSFNi are calculated in this article. Two important factors affecting the formation and migration energies: the vacancy concentration and Cu/Ni doping are studied. With Cu/Ni doping, the oxygen vacancy formation energy decreases [Evac (BSF??BSCF??BSFNi??BSFCu)]. The activation energies of BSFNi and BSFCu are lower than those of BSF and BSCF cathodes. Therefore, Cu/Ni-doped BSF shows the enhancement of electrochemical activity. We also calculated the surface migration energies of (011) Ba0.5Sr0.5Fe0.75Cu.0.25O3−δ for δ = 0.125, 0.25 and (001) Ba0.5Sr0.5Fe0.75(Cu/Ni)0.25O3−δ for δ = 0.125, which for (011) BSFCu are high

Mixed conducting perovskites such as Ba0.5Sr0.5Co0.75Fe0.25O3-δ (BSCF) are attracting interest for solid oxide fuel cells (SOFCs). Electrochemical behaviors of BSCF surfaces, compared to a bulk one, have not been investigated yet. In this paper, electrochemical properties of BSCF were investigated by density functional theory (DFT). We calculated barriers of the (011) BSCF terminated by SrCoO, and compared them with the bulk values. We found that the oxygen vacancy migration energies within 6.87–9.59 ? in depth in the slab are nearly similar to the bulk values. The surface oxygen vacancy migration energies in (011) and (001) slabs of BSCF were compared. They have two values in the (011) BSCF and vacancies migrate under two models, whic

In this study, crumpled-shape nanocomposite of nitrogen and sulfur co-doped ZnO–CeO2 (NSZC) was deposited on FTO substrate using one-step ultrasonic spray pyrolysis. Zinc acetate, cerium nitrate, and thiourea were dissolved in deionized water and used as starting solution. The samples were characterized using FESEM, XRD, UV–vis spectroscopy, EIS, and PL. The as-prepared nitrogen and sulfur co-doped ZnO–CeO2 nanocomposites were evaluated as high photocatalysts for degradation of methyl orange. Nearly 100% photocatalytic degradation of methyl orange was achieved for 180 min. The photoluminescence and electrochemical impedance spectroscopy revealed that co-doping of nitrogen and sulfur could promote the suppression of electron-hole rec

Single layer graphene quantum dots (GQDs), graphene nanosheets (GNSs), and carbon nanospheres (CNSs) were synthesized by an easy, environment-friendly, and low-cost hydrothermal process and the effect of the hydrothermal reaction time on their structural and photoluminescence properties was studied. Four different kinds of samples were prepared only using glucose and deionized water. By varying the hydrothermal reaction time, we obtained excitation-dependent photoluminescent GQDs and GNSs with different photoluminescence quantum yields (PLQYs) and CNSs without any photoluminescence. Atomic force microscopy images showed that the synthesized GQDs are single or double-layered. Transmission electron microscopy (TEM) images indicated that the s