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A novel method for the synthesis of a ternary platinum loaded reduced graphene oxide (rGO)/ zinc oxide (ZnO) hybrid nanocomposite via a pulsed laser ablation in liquid (PLAL) and direct current (DC) sputtering for a hydrogen sensing application is reported here. The said composite was fabricated to obtain small ZnO nanoparticles with interfacial electric contact without using chemical reagents. Firstly, ZnO nanoparticles were fabricated by the decomposition of zinc peroxide (ZnO2) quantum dots, synthesized by laser ablation of microstructured Zn powder in 3%H2O2, whereas GO was prepared by the modified Hummer method. Secondly, an rGO/ZnO nanocomposite was prepared via PLAL of ZnO and graphene oxide (GO) in deionized water. Finally, DC sputtering was used to decorate the surface of the rGO/ZnO hybrid with a Pt thin film to obtain a ternary rGO/ZnO/Pt hybrid nanocomposite. Maximum sensing performance was achieved by tuning the thickness of the deposited Pt layer. According to our study, the Pt-loaded rGO/ZnO gas sensor, with a thickness of 2 nm, showed an excellent response and selectivity towards a low concentration of hydrogen, giving a high response of about 99% (−400 ppm), which was 10 and 5 times higher than those of the pure ZnO, and the rGO/ZnO nanocomposite, respectively. This significantly improved response was mainly attributed to the high surface area of the rGO, the fast spill-over effect of the uniformly coated Pt nanoparticles, and the formation of a p-n junction between rGO and ZnO nanoparticles. This study indicates that the obtained rGO/ZnO/Pt hybrid nanocomposite is a promising candidate for constructing high-performance H2 gas sensors.

In this work, we report the preparation of superhydrophobic and superoleophilic surfaces on stainless steel meshes by spray-coating of Cerium(IV) oxide (CeO2) nanoparticles obtained by a co-precipitation method. The synthesized particles and the coated meshes were characterized using advanced techniques. Scanning electron microscopy images showed the particles to be present in distinct lumps; merged with each other on calcination to give a homogeneous structure. Transmission electron microscopy analyses showed the agglomeration of individual particles to form the clusters. Contact angle measurements revealed the superhydrophobic and superoleophilic nature of the modified mesh surface in air. Fourier transform infra-red analyses of the synthesized particles showed the characteristics peaks of CeO2 found in commercial samples. X-ray photoelectron spectroscopy of the glass coated with ceria confirmed the predominant presence of Ce4+ that also explained the wetting behavior. Oil-water separation studies using a simple gravity-driven setup showed high separation efficiency of an oil water mixture. An analytical model is discussed in detail to account for the wetting behavior and efficacy of the prepared surfaces in separating the two fluids. To summarize, this work presents a very simple and effective route for oil-water separation with high efficiency.

Separation of photo-generated charge carriers (electron and holes) is a major approach to improve the photovoltaic and photocatalytic performance of metal oxide semiconductors. For harsh environment like high temperature applications, ceramic like silicon carbide is very prominent. In this work, 10%, 20% and 40% by weight of pre-oxidized silicon carbide was coupled with titanium dioxide (TiO2) to form nanocomposite semiconductor via elegant pulsed laser ablation in liquid technique using second harmonic 532 nm wavelength of neodymium-doped yttrium aluminium garnet (Nd-YAG) laser. In addition, the effect of silicon carbide concentration on the performance of silicon carbide-titanium dioxide nanocomposite as photo-anode in dye sensitized solar cell and as photocatalyst in photodegradation of methyl orange dye in water was also studied. The result obtained shows that photo-conversion efficiency of the dye sensitized solar cell was improved from 0.6% to 1.65% and the percentage of methyl orange dye removed was enhanced from 22% to 77% at 24 min under ultraviolet–visible solar spectrum in the nanocomposite with 10% weight of silicon carbide. This remarkable performance enhancement could be due to the improvement in electron transfer phenomenon by the presence of silicon carbide on titanium dioxide.

Constructing nanocomposite structures with favorable charge transfer routes is an effective way to obtain highly efficient photocatalysts. Herein, fabrication of indirect and noble metal-free Z-scheme photocatalytic architecture is demonstrated using pulsed laser ablation in liquids (PLAL) technique for the first time. The as-prepared ternary photocatalyst (denoted as TiO2/rGO/g-C3N4) comprises titanium dioxide (TiO2) nanotubes, reduced graphene oxide (rGO) nanosheets, and graphitic carbon nitride (g-C3N4) nanosheets. The photocatalytic activity of the as-synthesized composite is evaluated by monitoring water splitting. Various analytical techniques were employed to investigate the compositional, morphological, structural, and optical properties of the photocatalysts. The system of TiO2/rGO/g-C3N4 with the weight ratio of TiO2 to g-C3N4 of 2:4 and 1% rGO exhibited the highest hydrogen production rate of 32 ± 1 mmol g−1h−1, which is about 93, 3.8 and 2.6 times higher than those of pure g-C3N4, TiO2, and TiO2/rGO, respectively. This enhanced performance can be ascribed to the strong interfacial bonding (TiO2-rGO-g-C3N4), extended visible light absorption capacity due to higher photo-responsiveness of rGO and g-C3N4, the synergetic effect between TiO2 and g-C3N4 and direct contact between TiO2 and rGO which facilitated efficient separation and transfer of photogenerated charges. This study opens opportunities for the fabrications of different Z-scheme systems for various applications.

Ag/C nanocomposite thin films with different Ag/C molar ratios have been prepared using ArF excimer laser-induced ablation process and silver target under n-Hexane atmosphere. The morphology, crystal structure and composition of as-deposited Ag/C nanocomposite thin films were investigated with high resolution electronic microscopic techniques (including scanning electron microscopy and transmission electron microscopy) and energy-dispersive X-ray spectroscopy, respectively. Laser Raman spectroscopy and Fourier transform infrared spectroscopy techniques were also applied to characterize the final carbonaceous products generated from n-Hexane under laser ablation process. The optical emission of the plume caused by the interaction between excimer laser and silver target in the presence of n-Hexane was studied to understand the possible reaction process. The UV–vis absorption of as-deposited Ag/C thin films, which is attributed to the surface plasmonic excitation, was also investigated in the present work.

Pulsed laser ablation in liquid (PLAL) with 532 nm wavelength laser with 5 ns pulse duration is used to produce the nanostructure copper oxide and the effects of oxidizing media (deionized water and hydrogen peroxide) on the composition, morphology and optical properties of the product materials produced by PLAL were studied. XRD and TEM studies indicate that in the absence of hydrogen peroxide, the product material is in two phases (Cu/Cu 2 O) with the spherical nanoparticle structure, whereas in the presence of hydrogen peroxide in the liquid medium, the product material revealed other two phases (Cu/CuO) with nanorod-like structure. The optical studies revealed a considerable red shift (3.34–2.5 eV) in the band gap energy in the case of hydrogen peroxide in the liquid medium in PLAL synthesis compared to the one in the absence of it. Also the product material in the presence of hydrogen peroxide in the liquid medium showed a reduced photoluminescence intensity indicating the reduced electron–hole recombination rate. The red shift in the band gap energy and the reduced electron–hole recombination rate make the product material an ideal photocatalyst to harvest solar radiation for various applications. The most relevant signals on the FTIR spectrum for the samples are the absorption bands in the region between 450 and 700 cm −1 which are the characteristics bands of copper oxygen bonds. The reported laser ablation approach for the synthesis of Cu 2 O and CuO nanoparticles has the advantages of being clean method with controlled particle properties.

We report structural and optical properties of Cu doped ZnO (ZnO:Cu) thin films deposited on glass substrate at room temperature by pulsed laser deposition (PLD) method without pre and post annealing contrary to all previous reports. For preparation of (ZnO:Cu) composites pure Zn and Cu targets in special geometrical arrangements were exposed to 248 nm radiations generated by KrF exciter laser. The laser energy was 200 mJ with 10 Hz frequency and 20 ns pulse width. The effect of Cu concentration on crystal structure, morphology, and optical properties were investigated by XRD, FESEM and photoluminescence spectrometer respectively. A systematic shift in ZnO (0 0 2) peak with Cu concentration observed in XRD spectra demonstrated that Cu ion has been incorporated in ZnO lattice. Uniform film with narrow size range grains were observed in FESEM images. The photoluminescence (PL) spectra measured at room temperature revealed a systematic red shift in ZnO emission peak and decrease in the band gap with the increase in Cu concentration. These results entail that PLD technique can be realized to deposit high quality crystalline ZnO and ZnO:Cu thin films without pre and post heat treatment which is normally practiced worldwide for such structures.

The study presented in this work deals with the synthesis of graphene/BiOBr composite following hydrothermal reaction between graphene oxide and BiOBr. The results achieved demonstrated that the presence of graphene on the surface of BiOBr significantly improved the photocatalytic activity, under visible light irradiation, owing to the low isoelectric characteristics of graphene and better interfacial electron transfer between BiOBr and graphene. The effect of different amounts of graphene such as 1, 3, 6 and 10 wt% on the photocatalytic and adsorption efficiency was investigated. Our results showed that there exists an optimum concentration of graphene (∼6 wt%) for the best photocatalytic response of BiOBr which could be due to crucial energy dissipation. The photocatalytic and adsorption efficiency of the composites were investigated by studying the removal of Sulforhodamine 640 dye as a probe reaction.

Nanomaterials are of great interest due to their applications in many fields. The structural and efficacy of nano-materials depend strongly on the method applied for their synthesis. In this work, nanosized nickel oxide (NiO) particles were prepared by pulsed laser ablation (PLA) technique in 3% H2O2 aqueous solution The structural and optical properties of the NiO were investigated by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscope (EDX), UV–Vis spectroscopy and Fourier-transform infrared spectroscopy (FT-IR). XRD analysis confirms that the phase is pure nickel oxide with lattice parameter = 0.42033 nm and 8 nm grain size while photoluminescence emission spectrum showed strong peak at 3.62 eV attributed to the band edge transition. FT-IR spectra depicts a strong band at ∼450 cm−1 which corresponds to the bending vibration of Ni–O bond. This work demonstrates that PLA is an effective method to control the size, impurity and minimal chemical waste generation which is the major problem with other wet chemical methods.

Tin dioxide (SnO 2 ) nanoparticles having 3 nm size were synthesized by irradiating pure tin metal using high power Nd:YAG laser in deionized water. Formation of nano-SnO 2 crystallites was confirmed by X-ray diffraction (XRD) and AFM study. UV–vis absorption spectral studies showed a peak at 240 nm. FTIR spectrum showed a band in the range of 400–700 cm −1 which was assigned to Sn–O antisymmetric vibrations. Photoluminescence spectrum of synthesized SnO 2 nanoparticles showed peak corresponding to 3.175, 2.901 and 2.613 eV respectively.

The effect of laser irradiation using three different wavelengths (IR, visible and UV) generated from Nd:YAG laser on the local glass structure as well as on the valence state of the copper ions in copper phosphate glass containing CuO with the nominal composition 0.30(CuO)–(0.70)(P2O5), has been investigated by X-ray photoelectron spectroscopy (XPS). The presence of asymmetry and satellite peaks in the Cu 2p spectrum for the unirradiated sample is an indication of the presence of two different valence states, Cu2+ and Cu+. Hence, the Cu 2p3/2 spectrum was fitted to two Gaussian–Lorentzian peaks and the corresponding ratio, Cu2+/Cutotal, determined from these relative areas clearly shows that copper ions exist predominately (>86%) in the Cu2+ state for the unirradiated glass sample under investigation. For the irradiated samples the symmetry and the absence of satellite peaks in the Cu 2p spectra indicate the existence of the copper ions mostly in Cu+ state. The O 1s spectra show slight asymmetry for the irradiated as well as unirradiated glass samples which result from two contributions, one from the presence of oxygen atoms in the P–O–P environment (bridging oxygen BO) and the other from oxygen in an P–O–Cu and PO environment (non-bridging oxygen NBO). The ratio of NBO to total oxygen was found to increase with laser power.

A pulsed laser emitting UV radiations generated by the third harmonic of Nd:YAG was applied for the synthesis of nano-structured ZnO 2 and ZnO. For the synthesis of nanoparticles of ZnO 2 , a high-purity metallic plate of Zn target was fixed at the bottom of a glass cell, in the presence of deionized water mixed with oxidizing agent H 2 O 2 , under repeated laser irradiation. The optical properties, size and the morphology of the synthesized ZnO 2 and ZnO by laser ablation was influenced strongly by post-annealing conditions which is not previously reported. By annealing ZnO 2 at 200 °C for 8 h, the product (ZnO 2 ) synthesized primarily was converted completely to ZnO. By variation of the annealing temperatures from 200 to 600 °C, the grain size of ZnO changes from 5 to 19 nm with a change in lattice parameters, the band gap and some other optical properties of nano-ZnO.