NSC50487

It has recently been established that the ideal bandgap for terrestrial photovoltaics is 1.37 eV and the bandgap for CulnSe2 is only around 1.04 eV. Thus, a larger bandgap is needed. However, neither the substitution of Ga nor of AI has made a high efficiency solar cell absorber with a band gap of 1.37 eV possible. B, an even smaller atom, should require less atomic substitution than either Ga or AI to achieve a wider bandgap. In order to fabricate a thin film of CulnxB1-xSe2 (CIBS), Cu, In and B were deposited from a variety of sputtering targets which were pure Cu, In, and B; a Cu.45ln.55; and a Cu3B2 target. Films were deposited simultaneously and sequentially. After deposition these films were post selenized in another vacuum chamber. Analysis of these films was accomplished using Raman spectroscopy, X-ray diffraction (XRD), and Auger electron spectroscopy (AES). With the difficulties encountered, materials were also deposited in a selenium atmosphere

Hierarchical TiO₂ Layers Prepared by Plasma Jets

Heterogeneous photocatalysis of TiO2 is one of the most efficient advanced oxidation processes for water and air purification. Here, we prepared hierarchical TiO2 layers (Spikelets) by hollow-cathode discharge sputtering and tested their photocatalytic performance in the abatement of inorganic (NO, NO2) and organic (4-chlorophenol) pollutant dispersed in air and water, respectively. The structural-textural properties of the photocatalysts were determined via variety of physico-chemical techniques (XRD, Raman spectroscopy, SEM, FE-SEM. DF-TEM, EDAX and DC measurements). The photocatalysis was carried out under conditions similar to real environment conditions. Although the abatement of NO and NO2 was comparable with that of industrial benchmark Aeroxide® TiO2 P25, the formation of harmful nitrous acid (HONO) product on the Spikelet TiO2 layers was suppressed. Similarly, in the decontamination of water by organics, the mineralization of 4-chlorophenol on Spikelet layers was interestingly the same, although their reaction rate constant was three-times lower. The possible explanation may be the more than half-magnitude order higher external quantum efficacy (EQE) compared to that of the reference TiO2 P25 layer. Therefore, such favorable kinetics and reaction selectivity, together with feasible scale-up, make the hierarchical TiO2 layers very promising photocatalyst which can be used for environmental remediation

REACTION PATHWAY INSIGHTS INTO THE SOLVOTHERMAL PREPARATION OF Culn\u3csub\u3e1- x\u3c/sub\u3eGa\u3csub\u3ex\u3c/sub\u3eSe\u3csub\u3e2\u3c/sub\u3e NANOCRYSTALLINE MATERIALS

Reaction pathway investigations of the solvothermal preparation of nanocrystalline Culn1- xGaxSe2 in triethylenetetramine reveal the early formation of a previously unreported Cu2-xSe(S) intermediate. Over 24 hours, this reacts with In and Se species to form CulnSe2(s). If Ga is present, the reaction proceeds over an additional 48 hours to form Culn1-xGaxSe2. Adding ammonium halide salts reduces the CulnSe2 formation time to as little as 30 minutes. It is proposed that in these cases, Cu2-xSe particle growth is limited via a competitive Cu-halide complex formation. The smaller Cu2-xSe particles may react and form CulnSe2 more rapidly. A reaction pathway scheme consistent with experimental results and previous literature reports is proposed

Anodic self-organized transparent nanotubular/porous hematite films from Fe thin-films sputtered on FTO and photoelectrochemical water splitting

In the present work, we investigate the self-organized anodic formation of nanotubular/porous hematite structures from Fe thin films on fluorine doped tin oxide (FTO) substrates. We show, for different metal film thicknesses, that transparent layers of an aligned 1D oxide morphology can be grown by complete anodization of sputtered iron films. The nanoporous or nanotubular structures show very different potentials for use as a photoanode for solar water splitting. Best performance under AM 1.5 (100 mW cm−2) conditions were found for a nanoporous hematite structure obtained after anodizing a 570-nm-thick iron film and using combined air/Ar annealing to maintain the nanoscale morphology

Photoanodes with Fully Controllable Texture: The Enhanced Water Splitting Efficiency of Thin Hematite Films Exhibiting Solely (110) Crystal Orientation

Hematite, α-Fe₂O₃, is considered as one of the most promising materials for sustainable hydrogen production <i>via</i> photoelectrochemical water splitting with a theoretical solar-to-hydrogen efficiency of 17%. However, the poor electrical conductivity of hematite is a substantial limitation reducing its efficiency in real experimental conditions. Despite of computing models suggesting that the electrical conductivity is extremely anisotropic, revealing up to 4 orders of magnitude higher electron transport with conduction along the (110) hematite crystal plane, synthetic approaches allowing the sole growth in that direction have not been reported yet. Here, we present a strategy for controlling the crystal orientation of very thin hematite films by adjusting energy of ion flux during advanced pulsed reactive magnetron sputtering technique. The texture and effect of the deposition mode on the film properties were monitored by XRD, conversion electron Mössbauer spectroscopy, XPS, SEM, AFM, PEC water splitting, IPCE, transient photocurrent measurements, and Mott–Schottky analysis. The precise control of the synthetic conditions allowed to fabricate hematite photoanodes exhibiting fully textured structures along (110) and (104) crystal planes with huge differences in photocurrents of 0.65 and 0.02 mA cm^–2 (both at 1.55 V <i>versus</i> RHE), respectively. The photocurrent registered for fully textured (110) film is among record values reported for thin planar films. Moreover, the developed fine-tuning of crystal orientation having a huge impact on the photoefficiency would induce further improvement of thin hematite films mainly if cation doping will be combined with the controllable texture