Solvothermal phase change induced morphology transformation in CdS/CoFe2O4@Fe2O3hierarchical nanosphere arrays as ternary heterojunction photoanodes for solar water splitting

Maitra, Soumyajit; Sarkar, Arundhati; Maitra, Toulik; Halder, Somoprova; Kargupta, Kajari; Roy, Sarbani

doi:10.1039/d1nj00864a

Cited by 19 publications

(11 citation statements)

References 91 publications

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“…Whereas the FCF electrode exhibited optimal photo-conversion e ciency of 1.25% (0.701 V), which was more than 1.34 times and 1.45 times that of the FFC and FCF electrodes, respectively. The ABPE and current density at 1.0V vs. SCE of the FCF electrode are higher than those of Maitra et al [35], and this FCF photoelectrode also showed better performance in terms of the light response.…”

Section: Electrochemical Properties Of the α-Fe 2 O 3 Filmscontrasting

confidence: 60%

Cobalt-doped double-layer α-Fe2O3 nanorod arraysfor enhanced photoelectrochemical reduction of Cr(Ⅵ)

Bai

Wang

Cui

et al. 2022

Preprint

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Element doping is one of the most important methods for improving the performance of photoelectrochemical (PEC) cells. It can change the electronic structure of the catalyst and the separation of the photogenerated charges and increase the carrier density, and thus energy density of the electrode materials. In this study, a Co-doped α-Fe2O3 double-layer electrode was prepared using a two-step hydrothermal method. Scanning electron microscope (SEM) showed that double-layer nanostructures were successfully deposited on a fluorine-doped tin oxide (FTO) substrate using this approach. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the doping did not materially change the morphology of the nanostructures, while diffuse reflectance spectrum (UV-vis DRS) showed that there were only slight changes to the flat bandgap. Electrochemical tests showed that doping greatly improved the current density irrespective of whether the cobalt was doped in the upper or the lower layer. The best performing configuration was that of the FTO/α-Fe2O3:Co/α-Fe2O3 electrode, which achieved a current density of 1.37 mA/cm2. The Co-doped double-layer α-Fe2O3 nanorod arrays proved to possess a high photoelectric synergistic ability for the reduction of Cr (VI) in an aqueous solution, with 84.85% reduction in 180 min. Under the influence of the electric field inside the double-layer electrode, the photoexcited electrons and holes are transferred to the surface of the FTO substrate and the photoanode, increasing the current density. This study offers an alternative approach for designing novel photoanodes with improved PEC performance by engineering the electron density distribution and band structure for efficient carrier separation.

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Section: Electrochemical Properties Of the α-Fe 2 O 3 Filmscontrasting

confidence: 60%

Cobalt-doped double-layer α-Fe2O3 nanorod arraysfor enhanced photoelectrochemical reduction of Cr(Ⅵ)

Bai

Wang

Cui

et al. 2022

Preprint

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“…Fe 2p core-level spectra is shown in Figure b. The peaks at 710.2 and 724.6 eV correspond to Fe 3+ 2p 3/2 and Fe 3+ 2p confirming the presence of Fe in its 3+ state present at the O h sites. ,,, Alongside this, peaks at 713.3 and 726.4 eV correspond to the presence of Fe 3+ 2p 3/2 and Fe 3+ 2p, confirming the presence of Fe in its 3+ state present at the tetrahedral sites, thereby showing that successful spinel inversion has occurred, because Fe is present in both octahedral and tetrahedral sites. ,,,,, The δ parameter can be calculated from the area ratio of the octahedral and tetrahedral site peaks of Fe 2p and Cu 2p, according to Fantauzzi et al The ratio of Fe:Cu in the analyzed sample CuFeM was observed to be 1.9. The general formula for CuFe 2 O 4 spinel is [Fe δ Cu 1−δ ]( T d )[Cu δ Fe 2−δ ](O h )O 4 .…”

Section: Resultsmentioning

confidence: 74%

“…The probable mechanism for the porosity enhancement is as follows. Alcoholic solution in the solvothermal process inhibits mineralization into hydroxides and oxyhydroxides, which, after annealing, can potentially lead to formation of impure oxides, thereby causing a direct change into copper ferrite from parent hematite without impurities as observed from our previous work A precursor solution containing a high concentration of Cu ions capped with surfactants in the absence of mineralizers are energetically deterred from forming clusters among themselves, but at the hematite/solution interface at high temperature in the autoclave, impregnation of these ligand-capped ions into the hematite lattice occurs, causing a direct phase change to copper ferrite. The impregnation of these ligand-capped ions into the hematite lattice under high pressure and temperature causes a change in morphology, resulting in enhanced porosity in the fabricated nanostructures.…”

Section: Methodsmentioning

confidence: 74%

“…Another essential property of ferrites is the partial occupation of A- and B-site cations at the tetrahedral and the octahedral sites. − Usually, this is described by the degree of inversion (δ). In a spinel with no inversion, δ = 0, since the tetrahedral sites have A atom occupancy value equal to 1 and octahedral sites also have B atom occupancy values equal to 1.…”

Section: Introductionmentioning

confidence: 99%

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Solvothermal Etching-Assisted Phase and Morphology Tailoring in Highly Porous CuFe₂O₄ Nanoflake Photocathodes for Solar Water Splitting

et al. 2021

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Improvization of synthetic strategies for designing novel nanostructures with desirable tailored morphology for efficient solar energy utilization has been at the focus of research on photoelectrochemical water splitting. This work presents a novel fabrication technique comprised of photocathodes comprised of highly porous copper ferrite nanoflake arrays by low-temperature surfactant-assisted solvothermal phase change induced temperature-controlled etching process. Solvothermally predeposited hematite on FTO glass was treated by a second solvothermal step, whereby surfactant-capped Cu2+ ions were forcibly impregnated into the hematite lattice at varying temperatures, resulting in phase change along with a drastic change in nanostructure morphology and crystal phase without the formation of any copper oxide surface impurities causing a temperature-dependent control over the degree of spinel inversion (δ), the underlying electronic properties of which were analyzed using DFT calculations. Analysis of photoelectrochemical (PEC) performance of the fabricated photocathodes was performed under A.M 1.5 G simulated solar illumination under a linear voltage sweep using a potentiostat with the three-electrode setup using 1 M H2SO4 aqueous solution as an electrolyte. The photocathode with δ = 0.77 exhibited the highest photocurrent density of −0.139 mA/cm2 at 0 V (vs RHE) and −2.57 mA/cm2 at −1 V (vs RHE). It also exhibited the highest IPCE % of 18.7%, which was higher than that of the photocathode with δ = 0.71, because of the depreciatory effect of high temperature on morphology, thereby emphasizing the precise synergistic influence of phase and morphology control simultaneously upon PEC performance. This work should inspire further research in developing unique wet chemical synthesis strategies for designing porous and highly ordered impurity-free nanostructures with temperature-dependent phase control for photoelectrode applications.

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“…Furthermore, room‐temperature PL spectra were measured to characterize the recombination rate of photocharge carriers. [ 29–31 ] From Figure 2d, peaks due to the band‐edge emission are observed around 595 nm (2.08 eV). The characteristic emission peaks of 50‐faceted Cu 2 O are much lower than others, indicating that the recombination of photocharge carriers could be effectively restrained, thus resulting in an enhanced photocatalytic activity for 50‐faceted Cu 2 O.…”

Section: Resultsmentioning

confidence: 99%

Mechanism Insight into an Unprecedented Dual Series‐Parallel Photocharge Separation in Quaternary Cu₂O Facet Junctions

Cui

Zhang

Huang

et al. 2022

Adv Funct Materials

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Uncovering the contribution of anisotropic crystal facets in single‐crystalline photocatalysts is still a challenge in fundamental study. Here, the mechanism underlying facet junction‐dependent photocharge separation in polyhedral Cu2O is demonstrated, which is beneficial for understanding why 50‐faceted Cu2O exhibiting quaternary {100}/{110}/{111}/{522} facet junction possesses an enhanced photodegradation activity toward tetracycline than that of the 26‐faceted Cu2O exhibiting ternary {100}/{110}/{111} and 18‐faceted Cu2O exhibiting binary {100}/{110} facet junction. Density functional theory (DFT) calculations and selective photodeposition results confirm that hierarchical facet junctions are formed in a 50‐faceted Cu2O, which could be regarded as one parallel connection between binary {110}/{111} and ternary {110}/{522}/{100} series facet junction for conduction band minimum, and another parallel connection between binary {100}/{522} and ternary {111}/{110}/{522} series facet junction for valence band maximum, leading to an unprecedented dual series‐parallel transfer pathway for more efficiently improved photocharge separation. Hopefully, this study would be a beneficial guideline for scientific researchers currently concentrating on the facet junction engineering of polyhedral photocatalysts.

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Solvothermal phase change induced morphology transformation in CdS/CoFe₂O₄@Fe₂O₃hierarchical nanosphere arrays as ternary heterojunction photoanodes for solar water splitting

Abstract: Design of efficient heterojunction photoanodes with appropriate band alignment and ease of charge separation has been one of the most highly focused research areas on photoelectrodes. This work demonstrates the...

Cited by 19 publications

References 91 publications

Cobalt-doped double-layer α-Fe2O3 nanorod arraysfor enhanced photoelectrochemical reduction of Cr(Ⅵ)

Cobalt-doped double-layer α-Fe2O3 nanorod arraysfor enhanced photoelectrochemical reduction of Cr(Ⅵ)

Solvothermal Etching-Assisted Phase and Morphology Tailoring in Highly Porous CuFe₂O₄ Nanoflake Photocathodes for Solar Water Splitting

Mechanism Insight into an Unprecedented Dual Series‐Parallel Photocharge Separation in Quaternary Cu₂O Facet Junctions

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Solvothermal phase change induced morphology transformation in CdS/CoFe2O4@Fe2O3hierarchical nanosphere arrays as ternary heterojunction photoanodes for solar water splitting

Abstract: Design of efficient heterojunction photoanodes with appropriate band alignment and ease of charge separation has been one of the most highly focused research areas on photoelectrodes. This work demonstrates the...

Cited by 19 publications

References 91 publications

Cobalt-doped double-layer α-Fe2O3 nanorod arraysfor enhanced photoelectrochemical reduction of Cr(Ⅵ)

Cobalt-doped double-layer α-Fe2O3 nanorod arraysfor enhanced photoelectrochemical reduction of Cr(Ⅵ)

Solvothermal Etching-Assisted Phase and Morphology Tailoring in Highly Porous CuFe2O4 Nanoflake Photocathodes for Solar Water Splitting

Mechanism Insight into an Unprecedented Dual Series‐Parallel Photocharge Separation in Quaternary Cu2O Facet Junctions

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Resources

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Solvothermal phase change induced morphology transformation in CdS/CoFe₂O₄@Fe₂O₃hierarchical nanosphere arrays as ternary heterojunction photoanodes for solar water splitting

Solvothermal Etching-Assisted Phase and Morphology Tailoring in Highly Porous CuFe₂O₄ Nanoflake Photocathodes for Solar Water Splitting

Mechanism Insight into an Unprecedented Dual Series‐Parallel Photocharge Separation in Quaternary Cu₂O Facet Junctions