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Production of a ZnO–rGO composite, using a novel one-pot method consisting in continuously flowing argon into a GO aqueous suspension heated at 80 °C, in the presence of galvanized iron steel scrap is presented. FTIR shows the complete disappearance of GO functional groups and only the C=C band remained, indicating extensive GO reduction. Raman spectra indicated sp2 character increase after reaction and the presence of the E2h mode of ZnO. SEM showed submicron crystals identified by XRD as ZnO in the hexagonal phase, while TEM images indicate ZnO nanoparticles decorate mainly the rGO borders. Optical band gap of 3.5 eV corresponding to ZnO, and optical transitions at 4.1 and 5.5 eV related with n → π and π → π* were observed. Electrochemical characterization by cyclic voltammetry shows an specific capacitance of 4.7 F g−1 at a scan rate of 5 mVs−1, which drops to ca. 0.8 F g−1 at 200 mVs−1. By electrochemical impedance spectroscopy, the relaxation time was ca. 5 ms. The proposed mechanism for the materials‘ synthesis includes Zn dissolution from scrap, galvanic displacement of oxygen moieties at the GO sheet, Zn deposition onto the carbon surface, and further oxidation and growth of ZnO nanocrystals.

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The local atomic structure of multilayer films of graphene oxide, cadmium sulfide, and cadmium sulfide−selenide was analyzed by Xray absorption fine structure spectroscopy. The films were prepared by sequential electrophoretic deposition and successive ion layer adsorption and reaction onto F-doped SnO 2 substrates. The obtained films were characterized by scanning electron microscopy, energy dispersive spectroscopy, Raman spectroscopy, UV−vis spectroscopy, and step-potential photocurrent response. From the transmittance data analysis, a direct band gap ranging from 2.13 to 2.3 eV was deduced. From photocurrent measurements, we conclude that films of CdS and CdSSe have photovoltaic properties suitable for utilization as an active layer in multilayer thin film hybrid solar cells. X-ray absorption near-edge structure spectra show a difference in amplitude between CdS/GO and CdSSe/GO samples, ascribed to a change in the local electronic structure around S. Extended X-ray absorption fine structure spectra show a direct C−S bond between the CdS/CdSSe nanoparticles and the graphene oxide layer. Band diagrams for the CdS/GO and CdSSe/GO electrolyte interfaces are proposed.

Abstract:The local electrical response in alkaline-doped CuInSe 2 films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe 2 (CIS) films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and photocurrent response. Increased crystallinity and surface texturing as the ion size increased were observed, as well as an enhanced photocurrent response in Cs-doped CIS. Li-and Na-doped films had larger conductivity than the undoped film while the K-and Cs-doped samples displayed shorter currents and the current images indicated strong charge accumulation in the Kand Cs-doped films, forming surface capacitors. Corrected current-sensing AFM IV curves were adjusted with the Shockley equation.

Abstract. Copper (Cu) and manganese (Mn) doped tissue equivalent Li 2 B 4 O 7 were prepared by solid state sintering. The glow curves shows a high temperature peak at 222 °C for Li 2 B 4 O 7 :Cu and for Li 2 B 4 O 7 :Mn at 218 °C. Linear dose response is observed up to 140 Gy. With a thermal treatment at 125 °C, the first peak of the phosphors doped with copper (95 °C) and manganese (90 °C) disappears and the main TL peaks remain isolated. The dose rate dependence was studied by exposing the samples at doses of 25 Gy and 250 Gy. At low dose it was observed that the Li 2 B 4 O 7 :Cu TL response has non-dependence on dose rate, and at higher dose was observed that there is a dependence of the TL response with the different dose rate until of 30%. For the case of Li 2 B 4 O 7 :Mn, the TL response has non-dependence on dose rate at low dose or high dose.

Abstract:The local electrical response in alkaline-doped CuInSe2 films prepared by single-step electrodeposition onto Cu substrates was studied by current-sensing atomic force microscopy. The CuInSe2 (CIS) films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and photocurrent response. Increased crystallinity and surface texturing as the ion size increased were observed, as well as an enhanced photocurrent response in Cs-doped CIS. Liand Na-doped films had larger conductivity than the undoped film while the K-and Cs-doped samples displayed shorter currents and the current images indicated strong charge accumulation in the K-and Cs-doped films, forming surface capacitors. Corrected current-sensing AFM IV curves were adjusted with the Shockley equation.

In this study, density functional theory has been used to investigate the structural and electronic properties of lead selenide (PbSe) and lead sulfide (PbS) semiconductors and their alloys PbSe1-xSx using the virtual crystal approximation (VCA) and random structure (RS) generations. The generalized gradient approximation (GGA) has been used to obtain lattice parameters which are compared with theory and experimental results. The generalized gradient approximation (MGGA) of TB09LDA has been used to calculate the electronic bands, for different sulfur compositions (0≤x≤1, ∆x=0.1). It has been observed that the transition from the valence band to the conduction band takes place at the L point, which agrees with previous theoretical investigations. It has been observed that both the bandgap and lattice parameters of the alloys obey Vegard's law. Effective band diagrams obtained from the unfolding of supercell band diagrams, reported for the first time for this system, show that the impacts of alloy disorder are low in the vicinity of the L point, indicating that the alloy composition do not appear to influence the transport phenomena. This work shows the suitability of the VCA approximation and the band unfolding method, to deal and describe the composition-dependent properties of the PbSe1-xSx pseudo binary alloys.