A single-step plasma enhanced-chemical vapor deposition (PE-CVD) route for the synthesis of F-doped iron(III) oxide nanomaterials is presented. Growth experiments, performed from a fluorinated Fe(II) ...β-diketonate precursor on Indium Tin Oxide (ITO) between 200 and 400 °C, yielded columnar β-Fe2O3 arrays with a preferential (100) growth direction. The fluorine content in the deposits could be adjusted by the sole variation of the deposition temperature controlling, in turn, the optical absorption and energy bandgap. Photocurrent measurements and Mott–Schottky analyses, carried out in Na2SO4 solution under one sun illumination, evidenced a conductivity switch from n- to p-type upon increasing fluorine amount in the obtained nanomaterials. The sample photocurrent density, donor content and flatband potential support the hypothesis that a progressive substitution of oxygen by fluorine in the iron(III) oxide lattice can alter electronic structure and extend charge carrier lifetimes, making anion-doped β-Fe2O3 an efficient water oxidation catalyst.
•Novel PE-CVD approach to β-Fe2O3 nanomaterials on ITO substrates.•Fabrication of columnar arrays with an homogeneous in-depth fluorine doping.•First example of β-Fe2O3 application in photoelectrochemical water splitting.•Modulation of optical and photoelectrochemical properties as a function of fluorine content.
We demonstrate the effect of hydrogen plasma treatment on hematite films as a simple and effective strategy for modifying the existing substrate to improve significantly the band edge positions and ...photoelectrochemical (PEC) performance. Plasma treated hematite films were consist of mixed phases (Fe sub(3)O sub(4): alpha -Fe sub(2)O sub(3)) which was confirmed by XPS and Raman analysis, treated films also showed higher absorption cross-section and were found to be a promising photoelectrode material. The treated samples showed enhance photocurrent densities with maximum of 3.5 mA/cm super(2) at 1.8 V/RHE and the photocurrent onset potentials were shifted from 1.68 V sub(RHE) (untreated) to 1.28 V sub(RHE) (treated). Hydrogen plasma treatment under non-equilibrium conditions induced a valence dynamics among Fe centers in the sub-surface region that was sustained by the incorporation of hydrogen in the hematite lattice as supported by the density functional theory calculations.
A major obstacle and persisting challenge towards safe and sustainable industrial scale processing and commercialization of perovskite based (opto)electronic devices including solar cells lies in the ...essential need of strongly coordinating toxic solvents such as N, N-dimethylformamide (DMF) in the preparation of perovskite precursor inks. In this work, we present novel ink systems for perovskite precursors composed of protic ionic liquids (PILs) based on methylammonium cation and carboxylate anion and their binary blends with water, alcohols and acetonitrile for solution processing of CH3NH3PbX3 (X = I, Br). Among the investigated ink-systems, new PIL methylammonium propionate and its blends were identified as the most promising candidates in terms of chemical stability and compatibility for single- and two-step solution processing of the perovskite materials. Multi-cation mixed halide perovskites solar cells prepared with PIL/acetonitrile solvent system showed power conversion efficiency in excess of 15%.
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•Methylammonium propionate a new stable room temperature protic ionic liquid is presented.•New binary hybrid perovskite ink systems with water, ethanol, isopropanol and acetonitrile as (co)-solvents are presented.•Ink-jet printing of CH3NH3PbI3 was demonstrated using methylammonium propionate/water based perovskite inks.•MAP/DMSO/acetonitrile solvent system was applied for sequential deposition of (MA0.15FA0.85)Pb(I0.85Br0.15)3 thin films.
Nanostructured α-Fe2O3 thin films were grown by plasma-enhanced chemical vapor deposition (PE-CVD) using iron pentacarbonyl (Fe(CO)5) as precursor. Influence of the plasma parameters on ...photoelectrochemical (PEC) properties of the resulting hematite thin films toward solar oxidation of water was investigated under one sun illumination in a basic (1 M NaOH) electrolyte. PEC data analyzed in conjunction with the data obtained by scanning electron microscopy, X-ray diffraction and Mott–Schottky analysis showed 100 W plasma power to be an optimal RF-power value for achieving a high photocurrent density of ∼1098 μA/cm2 at 0.9 V/SCE external applied potential. The donor density, flat band potential, grain size and porosity of the films were observed to be highly affected by RF-power, which in turn resulted in enhanced photoresponse.
A single-step plasma enhanced-chemical vapor deposition (PE-CVD) route for the synthesis of F-doped iron(III) oxide nanomaterials is presented. Growth experiments, performed from a fluorinated Fe(II) ...beta -diketonate precursor on Indium Tin Oxide (ITO) between 200 and 400 degree C, yielded columnar beta -Fe sub(2)O sub(3) arrays with a preferential (100) growth direction. The fluorine content in the deposits could be adjusted by the sole variation of the deposition temperature controlling, in turn, the optical absorption and energy bandgap. Photocurrent measurements and Mott-Schottky analyses, carried out in Na sub(2)SO sub(4) solution under one sun illumination, evidenced a conductivity switch from n- to p-type upon increasing fluorine amount in the obtained nanomaterials. The sample photocurrent density, donor content and flatband potential support the hypothesis that a progressive substitution of oxygen by fluorine in the iron(III) oxide lattice can alter electronic structure and extend charge carrier lifetimes, making anion-doped beta -Fe sub(2)O sub(3) an efficient water oxidation catalyst.
We present an easy and scalable production method for transparent electrodes based on silver nanowires and silver nanowire/single-wall carbon nanotube hybrid films. We applied dip coating on glass ...and flexible polyethylene terephtalate foils. The foils were treated with oxygen plasma in order to increase the hydrophilicity of the surface. After the plasma treatment, the foils could be wet-coated as easy and fast as the glass substrates. Several silver nanowire films were coated with two different carbon nanotube inks. Hereby, the carbon nanotubes are supposed to function as an electrical bridge between the silver nanowires in order to decrease the sheet resistance. We found that shorter metallic enriched carbon nanotubes contributed a stronger increase on the conductivity than longer unsorted carbon nanotubes. This result for silver/carbon nanotube hybrid films is opposed to the trends for pure carbon nanotube networks, where the length of the carbon nanotubes has a stronger effect compared to the amount of metallic carbon nanotubes.
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