CuNb<sub>3</sub>O<sub>8</sub>: A p-Type Semiconducting Metal Oxide Photoelectrode

Joshi, Upendra A.; Maggard, Paul A.

doi:10.1021/jz300477r

Cited by 124 publications

(114 citation statements)

References 41 publications

(55 reference statements)

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“…Specifically, the IO CuFeO 2 /C 60 /CoFe LDH yielded a photocurrent of 4.86 mA cm −2 at 0 V versus RHE, which is more than twice the HER performance of the planar CuFeO 2 /C 60 /CoFe LDH photocathode. [4][5][6][7]46] To investigate the charge transport/transfer behaviors for both IO and planar CuFeO 2 -based photocathodes, electrochemical impedance spectroscopy (EIS) measurements were carried out in argon-purged 1 m NaOH electrolyte under simulated solar illumination as shown in Figure S10 (Supporting Information). Notably, our IO CuFeO 2 /C 60 /CoFe LDH photocathode exhibits a record-high photocurrent density (5.2 mA cm −2 at −0.1 V vs RHE) among CuFeO 2 -based photocathodes and outperforms most of the previously reported p-type ternary oxide-based photocathodes in the literature, as summarized in Table S1 (Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

Yang

Tan

et al. 2019

Adv Funct Materials

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P-type semiconductors based on ternary oxides have attracted wide interest owing to their earth-crust abundance and favorable optoelectronic properties. Among the p-type ternary oxides, delafossite-phase CuFeO 2 has received considerable attention because it has the potential to fully harness visible light (<800 nm) owing to its narrow bandgap (1.4-1.6 eV). Despite the favorable optoelectronic properties predicted by theoretical studies, CuFeO 2 photocathodes have low quantum efficiency under visible light near the bandgap edge, which is a major bottleneck for efficient solar-to-hydrogen conversion. Herein, a novel method is presented for boosting visible-light harvesting in the CuFeO 2 photocathode by employing an inverse opal structure as a periodic macrostructure. The periodic macroporous structure allows exceptional near-bandgap photon harvesting, particularly within the range of 600-700 nm, owing to the enhanced light absorption due to multiple scattering together with the short diffusion distance for minority carriers toward the electrolyte. After surface modification with a low-cost double hydroxide electrocatalyst, our CuFeO 2 -based photocathode exhibits a record-breaking photocurrent density of 5.2 mA cm −2 at −0.1 V with respect to the reversible hydrogen electrode for water reduction among p-type ternary oxide-based photocathodes.

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Section: Resultsmentioning

confidence: 99%

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

Yang

Tan

et al. 2019

Adv Funct Materials

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“…38 The band gap (E g ) of the samples were estimated from Tauc plots by following procedures similar to those reported earlier. 19,39,40 PL of the powder samples was carried out at room temperature on a Shimadzu RF-5301PC spectrofluorophotometer with an excitation wavelength of 350 nm. The excitation and emission slits of 5 nm width were used to record the spectra.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Efficient COD Removal Coinciding with Dye Decoloration by Five-Layer Aurivillius Perovskites under Sunlight-Irradiation

Gutta

Mandal

2015

ACS Sustainable Chem. Eng.

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An absorption edge in the visible region and a slow recombination of photogenerated electron−hole pairs in semiconductors are desirable for efficient sunlight-driven photocatalysis. One of the strategies to harvest visible-light instead of ultraviolet is to identify or develop new semiconductors with a band gap below 3 eV. The five-layer Aurivillius phase perovskites, Bi 6−x La x Ti 3 Fe 2 O 18 (x = 0, 1), where the band gap ranges from ∼2.02−2.57 eV, have been identified as potential members. The compounds, Bi 6−x La x Ti 3 Fe 2 O 18 (x = 0, 1), are synthesized by solid state reaction and characterized by PXD, FE-SEM, EDS, UV−vis DRS, and PL spectroscopy. La-substitution into Bi 6 Ti 3 Fe 2 O 18 results in a sluggish recombination of photogenerated electron−hole pairs in Bi 5 LaTi 3 Fe 2 O 18 as compared to the parent. The compounds showed remarkable photocatalytic performance toward Rhodamine B (RhB) degradation (more than 96%) within 30 min of sunlight-irradiation under mild acidic medium. Dye degradation is found to be coincident with COD removal. Moreover, the photocatalytic cycle test demonstrated the catalysts to be highly stable and reusable after five catalytic cycles without any noticeable decrease in the activity. Because of the fact that reactive oxygen species (ROS) are generated by sunlight-irradiation over the layered perovskite catalysts and that up to 95% COD removal takes place within 30 min, the catalysts may find practical application in dye/organic contaminant degradation or waste treatment that is sustainable without incurring any additional energy cost.

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“…14,15 Many of these p-type oxides, incl. p-CuCrO 2 16 p-CuAlO 2 , 17 p-CuGaO 2 18 and p-CuFeO 2 19, 20 …”

Section: Introductionmentioning

confidence: 99%

Electronic structure, photovoltage, and photocatalytic hydrogen evolution with p-CuBi₂O₄ nanocrystals

et al. 2016

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a As a visible light active p-type semiconductor, CuBi2O4 is of interest as a photocatalyst for the generation of hydrogen fuel from water. Here we present the first photovoltage and photocatalytic measurements on this material and DFT results on its band structure. Single crystalline CuBi2O4 nanoparticles (25.7 ± 4.7 nm) were synthesized from bismuth and cupric nitrate in water under hydrothermal conditions. Powder X-ray diffraction (XRD) confirms the CuBi2O4 structure type and UV-Vis spectroscopy observes a 1.75 eV optical band gap. Surface photovoltage (SPV) measurements on CuBi2O4 nanoparticle films on fluorine doped tin oxide yield 0.225 V positive photovoltage at >1.75 eV photon energy confirming holes as majority carriers. The photovoltage is reversible and limited by light absorption. When dispersed in 0.075 M aqueous potassium iodide solution, the CuBi2O4 particles support photochemical hydrogen evolution of up to 16 µmol h-1 under ultraviolet but not under visible light. Based on electrochemical scans, CuBi2O4 is unstable towards reduction at -0.2 V, but pH-dependent photocurrents of 6.45 A cm -2 with an onset potential of +0.75 V vs. NHE can be obtained with 0.01 M Na2S2O8 as a sacrificial electron acceptor. The photoelectrochemical properties of CuBi2O4 can be explained on the basis of the band structure of the material. DFT calculations show the valence and conduction band edges to arise primarily from the combination of O 2p and Cu 3d orbitals, respectively, with additional contributions from Cu 3d and Bi 6s orbitals just below the Fermi level. Trapping of photoelectrons in the Cu 3d band is the cause for reductive photocorrosion of the material, while the p-type conductivity arises from copper vacancy states near the VB edge. These findings provide an improved understanding of the photophysical properties of p-CuBi2O4 and its limitations as a proton reduction photocatalyst.A) The DFT+U electronic band structures of (left) pristine CuBi2O4 and (right) VCu -CuBi2O4. The Fermi level (EF) is set at 0 eV. The presence of VCu leads to partial occupation of the bands around the VB edge. This gives rise to p-type behavior in CuBi2O4. B) The DFT+U projected density of states of VCu -CuBi2O4.

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CuNb₃O₈: A p-Type Semiconducting Metal Oxide Photoelectrode

Cited by 124 publications

References 41 publications

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

Efficient COD Removal Coinciding with Dye Decoloration by Five-Layer Aurivillius Perovskites under Sunlight-Irradiation

Electronic structure, photovoltage, and photocatalytic hydrogen evolution with p-CuBi₂O₄ nanocrystals

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CuNb3O8: A p-Type Semiconducting Metal Oxide Photoelectrode

Cited by 124 publications

References 41 publications

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

Boosting Visible Light Harvesting in p‐Type Ternary Oxides for Solar‐to‐Hydrogen Conversion Using Inverse Opal Structure

Efficient COD Removal Coinciding with Dye Decoloration by Five-Layer Aurivillius Perovskites under Sunlight-Irradiation

Electronic structure, photovoltage, and photocatalytic hydrogen evolution with p-CuBi2O4 nanocrystals

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CuNb₃O₈: A p-Type Semiconducting Metal Oxide Photoelectrode

Electronic structure, photovoltage, and photocatalytic hydrogen evolution with p-CuBi₂O₄ nanocrystals