First-principles density functional theory (DFT) calculations were carried out to investigate the structural and electronic properties of beryllium (Be) doped and, Be with boron (B) co-doped graphene systems.

Composites of boron nitride (BN) and carboxylated graphene are prepared for the fi rst time using covalent cross-linking employing the carbodiimide reaction. The BN 1-x G x ( x ≈ 0.25, 0.5, and 0.75) obtained are characterized using a variety of spectroscopic techniques and thermogravimetric analysis. The composites show composition-dependent electrical resistivity, the resistivity decreasing with increase in graphene content. The composites exhibit microporosity and the x ≈ 0.75 composite especially exhibits satisfactory performance with high stability as an electrode in supercapacitors. The x ≈ 0.75 composite is also found to be a good electrocatalyst for the oxygen reduction reaction in fuel cells.

A novel europium (Eu) and terbium (Tb) co-doped ZnO nanoparticles had been synthesized by a facile, cost efficient and rapid combustion method. The physical and chemical properties of the as-synthesized nanoparticles were determined by XRD, SEM, EDS, BET, FTIR, XPS, UV-vis DRS, PL, EIS and photocurrent density. XRD patterns confirm that Eu and Tb ions are stably inserted into the framework of ZnO, and the crystallite size decreases to 21 nm compared to that of pure ZnO (32 nm) as the amount of co-dopants increases to optimal value (3 mol% of each). With the insertion of Eu and Tb ions into ZnO, the recombination rate of photo generated charge carriers is found to be low. It is observed that doped Eu and Tb ions can enter the lattice structure of ZnO with a suitable doping concentration, and the obtained doped ZnO have ordered hexagonal wurtzite structures and nearly spherical morphology with high specific surface area and high porosity. Meanwhile, the introduction of Eu and Tb ions can effectively extend the spectral response from UV to visible region for the catalysts, thus reducing the band gap from 3.25 to 2.91 eV. Further analysis by means of XPS measurement showed that the existence of mixture of Eu 2+/ Eu 3+ and Tb 3+/ Tb 4+ oxidation states and high content of the surface chemisorbed oxygen species also contributed to the high photocatalytic activity. It was found that Eu and Tb co-doped ZnO shows highly efficient and stable visible light activity and provides a 100% MB degradation within 15 min, while the degradation time for Eu doped ZnO and Tb doped ZnO is reduced gradually to 50 and 42 min, respectively to obtain the 100% MB degradation. It was also found that the photocatalytic hydrogen evolution activity over Eu and Tb co-doped ZnO can be significantly increased to 533.8 and 792 µmol with 0.2 wt% catalyst dose and initial solution pH 9, respectively under similar conditions with good stability. Moreover, simultaneous introduction of Eu and Tb effectively promoted the yield of CH 4 to 4.59 µmol, which was 3.4 fold higher in comparison to pure ZnO. Thus the present approach could provide a versatile strategy for the synthesis of novel and efficient visible light activated photocatalysts.

Covalent assemblies of MoS2and MoS2–RGO are synthesized by Sonogashira coupling, which exhibit high CO2and H2uptake as well as enhanced hydrogen evolution activity due to generated pores and more exposed edges.

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It has been possible to bestow significantly improved mechanical properties on a porous MOF by incorporating BN nanosheets.

Nanocomposites of ZnO have been synthesized by auto-combustion technique to study their electrical (dielectric and direct current), optical, and structural properties by increasing copper content in these composites. Techniques used for characterizing these composite nanoparticles involve X-ray diffraction, scanning electron microscopy, UV-vis spectrophotometry, and photoluminescence spectroscopy. X-ray diffraction patterns suggested hexagonal wurtzite structure of ZnO, which remains unchanged upon increasing the amount of Cu dopant. However, there is a noticeable decrease in the particle size with rising Cu content. Morphology of the crystallites, as observed by scanning electron microscopy, is nearly spherical. Dielectric parameters, including dielectric constant and dielectric loss, decrease, whilst AC conductivity increases with the increase of Cu content as well as with the rise of frequency of the applied alternating biasing field. In addition, DC electrical conductivity is also improved by the enhancement of Cu doping percentage and temperature. These variations of electrical parameters of nanocomposites allow their potential utilization in those devices which are operated at high frequencies. Band gap energy Eg, analyzed by UV-vis spectrophotometer, is noticed to decrease upon rising Cu content from 3.39 eV to 2.46 eV, and depicts a red shift from UV to visible light region. PL emission intensity decreased in the studied light spectrum by increasing Cu content implying that the recombination rate of photo-induced charge carriers decreases effectively. Thus, upon Cu doping reduction in Eg occurs, which along with the reduced recombination rates of photogenerated electrons and holes pairs, becomes a cause of the participation of more and more charge carriers in the photocatalysis process in order to degrade the organic compounds.