Genesis of enhanced photoactivity of CdS/Nix nanocomposites for visible-light-driven splitting of water

A series of CdS/Ni_x nanocomposite photocatalysts, containing ca. 0.6–15 wt% Ni, were synthesized using a one-step hydrothermal method and characterized for their crystallographic, morphological, interfacial, and optical properties. Rietveld refinement of powder XRD data revealed the coexistence of wurtzite (hexagonal) and zinc blende (cubic) phases of CdS in ratios dependent on Ni content. Only a fraction of Ni existed as a secondary phase of NiS while the majority occupied the lattice positions of hexagonal CdS. Whereas up to 10-fold enhancement in H₂ evolution compared with pure CdS was observed for samples containing ∼1.5–4.5 wt% Ni, samples with smaller or larger Ni content displayed poor activity for visible-light-induced splitting of water in presence of sulfide–sulphite ions as sacrificial electron donors. In contrary to recent findings, our study reveals that the enhanced CdS photoactivity is not a result of charge transfer between p-type NiS and n-type CdS, Ni-induced visible-region absorbance, or the coating of CdS particles by non-photoactive NiS. Instead, the preparation-dependent hexagonal/cubic CdS phase boundaries and particle morphology may play a crucial role. Additionally, certain Ni-doping-induced sub-bandgap shallow energy levels contribute to charge carrier separation.     

Synthesis and characterization of pure anatase TiO<Subscript>2</Subscript> nanoparticles

Pure anatase TiO₂ nanoparticles were synthesized by microwave assisted sol–gel method and further characterized by powder X-ray diffraction (XRD), energy dispersive x-ray analysis (EDAX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–Visible spectrophotometer, SEM images showed that TiO₂ nanoparticles were porous structure. The XRD patterns indicated that TiO₂ after annealed at 300 °C for 3 h was mainly pure anatase phase. The crystallite size was in the range of 20–25 nm, which is consistent with the results obtained from TEM images. Microwave heating offers several potential advantages over conventional heating for inducing or enhancing chemical reactions.     

Capture of carbon dioxide over porous solid adsorbents lithium silicate,lithium aluminate and magnesium aluminate at pre-combustion temperatures

The capturing process for carbon dioxide over porous solid adsorbents such as lithium silicate, lithium aluminate, and magnesium aluminate at pre- combustion temperatures was studied. Lithium silicate was prepared by the sol gel and solid fusion methods. The lithium silicate adsorbent was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and surface area. The capturing of carbon dioxide over lithium silicate, lithium aluminate, and magnesium aluminate was explored at different experimental conditions such as exposure time, temperature variation, and exposure carbon dioxide pressure. The capturing process for carbon dioxide was investigated over these adsorbents with variation of their metal mole ratios. The effect of the addition of (promoter) sodium, potassium, and cesium in the lithium silicate adsorbent was explored to investigate the variation of the capture of carbon dioxide over these adsorbents.     

Photocatalytic activity of Eu3＋-doped ZnO nanorods synthesized via microwave assisted technique

The doped ZnO nanorods as a photocatalyst with different Eu contents were prepared by microwave assisted method and they were characterized by means of X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),UV-Vis spectroscopy,surface area Brunauer-Emmett-Teller(BET),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The average crystallite size and band gap energy of Eu-doped ZnO were varied with the Eu content.The XRD pattern of Eu-doped ZnO indicated hexagonal crystal structure with an average crystallite size of 25 nm.The presence of europium with trivalent state and its doping successfully into the crystal lattice of ZnO matrix were confirmed by XPS technique.The photocatalytic activity of Eu-doped ZnO nanorods was evaluated for methyl orange degradation.The photocatalytic experiments showed ～91% degradation of methyl orange over 0.2 mol.% Eu doped ZnO sample within 3 h under UV light(365 nm).