The behavior of hydrothermally synthesized hematite nanorods prepared on spin coated seed layers

Herein we report on the effect of varied spin-coated seed layer concentrations of Iron (III) chloride hexahydrate (FeCl3.6H2O) on the photoelectrochemical performance of hydrothermally synthesized hematite nanorods. The seed layers were prepared from 0.05, 0.07, 0.09, 0.11, and 0.13 M concentrations of FeCl3.6H2O. The nanorods were vertically aligned with slight inclinations over the seed layers with the two lowest molar concentrations (0.05 and 0.07 M) of FeCl3.6H2O. A further increase in seed layer concentrations transformed the nanorods as they grew over others and agglomerated into clusters. Structural analysis using X-ray diffraction (XRD) and Raman spectroscopy demonstrated uniform hematite crystalline peaks for all the samples. All samples absorbed highly in the visible region within an onset absorption edge wavelength ranging from 624 to 675 nm. Overall, the nanorods synthesized over the lowest seed layer concentration of 0.05 M of FeCl3.6H2O exhibited the highest photocurrent density of 0.077 mA/cm2 at 1.5 V vs. reversible hydrogen electrode. The results obtained provide important information about the structural, optical, and photoelectrochemical properties of hematite nanorods synthesized over varied seed layer concentrations. This is a key contribution in understanding and enhancing the hematite nanorods performance for photocatalytic applications.

Fabrication of 3D hierarchical Fe2O3/SnO2 photoanode for enhanced photoelectrochemical performance

Exploring and fabricating a suitable photoanode with high catalytic activity is critical for enhancing photoelectrochemical (PEC) performance. Herein, a novel 3D hierarchical Fe2O3/SnO2 photoanode was fabricated by a hydrothermal route, combining with an annealing process. The morphology, crystal structure were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photon spectroscopy (XPS), and X-ray diffraction (XRD), respectively. The results reveal the successful preparation of Fe2O3 nanothorns on the surface of SnO2 nanosheets. The as-fabricated 3D Fe2O3/SnO2 photoanode yields obviously promoted PEC performance with a photocurrent density of approximate 5.85 mA cm-2, measured in a mixture of Na2S (0.25 M) and Na2SO3 (0.35 M) aqueous solution at 1.23 V (vs. reversible hydrogen electrode, RHE). This value of photocurrent is about 53 times higher than that of the bare SnO2 photoanode. The obvious improved PEC properties can be attributed to the 3D Fe2O3/SnO2 heterostructures that offer outstanding light harvesting ability as well as improved charge transport and separation. These results suggest that exploring a suitable 3D hierarchical photoanode is an effective approach to boost PEC performance.approach to boost PEC performance.

A highly enhanced photoelectrochemical performance of BiVO4 photoanodes modified with CoPi groups by increasing energy band bending, accelerating hole separation and improving water oxidation kinetics

BiVO4 is one of the most attractive photoanode materials for photoelectrochemical water splitting. Herein, cobalt phosphate (CoPi) modified BiVO4 (BiVO4/CoPi) photoanode is prepared by electrodeposition. The physical and chemical characterization...

Exploring the Modulation Mechanism of LSPR Effect of Cu Periodic Nanosphere Arrays to Promote the Performance of TiO2 Photoelectrode

Based on the previous exploration of the localized surface plasmon resonance (LSPR) effect of isolated Cu nanospheres to enhance the photoelectrochemical performance of TiO2 photoelectrode, this work further arranged Cu...

Study of the photoelectrochemical activity of ZnO: Ag/rGO photo-anodes synthesized by two-steps sol-gel method

This work investigate the influence of Silver Plasmon and reduced graphene oxide (rGO) on the photoelectrochemical performance (PEC) of ZnO thin films synthesized by the sol-gel method. The physicochemical properties of the obtained photo-anodes were systematically studied using several characterization techniques. The X-ray diffraction analysis showed that all samples presented hexagonal Wurtzite structure with apolycrystalline nature. Raman and EDX studies confirmed the existence of both Ag and rGO in ZnO: Ag/rGO thin films. The estimated grain size obtained from (SEM) analysis decreased with Ag doping, then increased to a maximum value after rGO addition. The UV-vis transmission spectra of the as-prepared ZnO: Ag and ZnO: Ag/rGO thin films have shown a reduction in the visible range with a redshift at the absorption edges. The bandgaps were estimated to be around 3.17, 2.7, and 2.52 eV for ZnO, ZnO: Ag, and ZnO: Ag/rGO, respectively. Moreover, the electrical measurements revealed that the charge exchange processes were enhanced at the ZnO: Ag/rGO/electrolyte interface, accompanied by an increase in the (PEC) performance compared to ZnO and ZnO: Ag photo-anodes. Consequently, the photocurrent density of ZnO: Ag/rGO (0.2 mA.cm-2) was around 4 and 2.22 times higher than photo-anodes based on undoped ZnO (0.05 mA.cm-2) and ZnO: Ag (0.09 mA.cm-2), respectively. Finally, from the flat band potential and donor density, deduced from the Mott-Schottky, it was clear that all the samples were n-type semiconductors with the highest carrier density for the ZnO: Ag/rGO photo-anode.

Stable and Efficient Photoinduced Charge Transfer of MnFe2O4/Polyaniline Photoelectrode in Highly Acidic Solution

Tailoring conductive polymers with inorganic photocatalysts, which provide photoinduced electron-hole generation, have significantly enhanced composites leading to excellent photoelectrodes. In this work, MnFe2O4 nanoparticles prepared by a hydrothermal method were combined with polyaniline to prepare mixed (hybrid) slurries, which were cast onto flexible FTO to prepare photoelectrodes. The resulting photoelectrodes were characterized by XRD, FESEM, HRTEM and UV-VIS. The photoelectrochemical performance was investigated by linear sweep voltammetry and chronoamperometry. The photocurrent achieved by MnFe2O4/Polyaniline was 400 μA/cm2 at 0.8 V vs. Ag/AgCl in Na2SO4 (pH = 2) at 100 mW/cm2, while polyaniline alone achieved only 25 μA/cm2 under the same conditions. The best MnFe2O4/Polyaniline displayed an incident photon-to-current conversion efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) of 60% at 405 nm wavelength, and 0.17% at 0.8 V vs. Ag/AgCl, respectively. High and stable photoelectrochemical performance was achieved for more than 900 s in an acidic environment.