An official website of the United States government
This content will become publicly available on August 6, 2025
Atomic doping to enhance the p-type behavior of BiFeO 3 photoelectrodes for solar H 2 O 2 production
Na-doped BiFeO3demonstrates an enhanced p-type behavior compared to p-type BiFeO3prepared without extrinsic dopants, and Na-doped BiFeO3can serve as a photocathode for solar O2reduction to H2O2when coupled with Ag nanoparticle catalysts.
more »
« less
- Award ID(s):
- 2203633
- PAR ID:
- 10537505
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 12
- Issue:
- 31
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 20437 to 20448
- Subject(s) / Keyword(s):
- BiFeO3 photoelectrodes H2O2 production
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract The solid‐state synthesis of perovskite BiFeO3has been a topic of interest for decades. Many studies have reported challenges in the synthesis of BiFeO3from starting oxides of Bi2O3and Fe2O3, mainly associated with the development of persistent secondary phases such as Bi25FeO39(sillenite) and Bi2Fe4O9(mullite). These secondary phases are thought to be a consequence of unreacted Fe‐rich and Bi‐rich regions, that is, incomplete interdiffusion. In the present work, in situ high‐temperature X‐ray diffraction is used to demonstrate that Bi2O3first reacts with Fe2O3to form sillenite Bi25FeO39, which then reacts with the remaining Fe2O3to form BiFeO3. Therefore, the synthesis of perovskite BiFeO3is shown to occur via a two‐step reaction sequence with Bi25FeO39as an intermediate compound. Because Bi25FeO39and the γ‐Bi2O3phase are isostructural, it is difficult to discriminate them solely from X‐ray diffraction. Evidence is presented for the existence of the intermediate sillenite Bi25FeO39using quenching experiments, comparisons between Bi2O3behavior by itself and in the presence of Fe2O3, and crystal structure examination. With this new information, a proposed reaction pathway from the starting oxides to the product is presented.more » « less
-
We report on growth and electrical properties of α-Ga2O3films prepared by halide vapor phase epitaxy (HVPE) at 500 °C on α-Cr2O3buffers predeposited on sapphire by magnetron sputtering. The α-Cr2O3buffers showed a wide microcathodoluminescence (MCL) peak near 350 nm corresponding to the α-Cr2O3bandgap and a sharp MCL line near 700 nm due to the Cr+intracenter transition. Ohmic contacts to Cr2O3were made with both Ti/Au or Ni, producing linear current–voltage ( I– V) characteristics over a wide temperature range with an activation energy of conductivity of ∼75 meV. The sign of thermoelectric power indicated p-type conductivity of the buffers. Sn-doped, 2- μm-thick α-Ga2O3films prepared on this buffer by HVPE showed donor ionization energies of 0.2–0.25 eV, while undoped films were resistive with the Fermi level pinned at ECof 0.3 eV. The I– V and capacitance–voltage ( C– V) characteristics of Ni Schottky diodes on Sn-doped samples using a Cr2O3buffer indicated the presence of two face-to-face junctions, one between n-Ga2O3and p-Cr2O3, the other due to the Ni Schottky diode with n-Ga2O3. The spectral dependence of the photocurrent measured on the structure showed the presence of three major deep traps with optical ionization thresholds near 1.3, 2, and 2.8 eV. Photoinduced current transient spectroscopy spectra of the structures were dominated by deep traps with an ionization energy of 0.95 eV. These experiments suggest another pathway to obtain p–n heterojunctions in the α-Ga2O3system.more » « less
-
Abstract The field of photovoltaics is revolutionized in recent years by the development of two–dimensional (2D) type‐II heterostructures. These heterostructures are made up of two different materials with different electronic properties, which allows for the capture of a broader spectrum of solar energy than traditional photovoltaic devices. In this study, the potential of vanadium (V)‐doped WS2is investigated, hereafter labeled V‐WS2, in combination with air‐stable Bi2O2Se for use in high‐performance photovoltaic devices. Various techniques are used to confirm the charge transfer of these heterostructures, including photoluminescence (PL) and Raman spectroscopy, along with Kelvin probe force microscopy (KPFM). The results show that the PL is quenched by 40%, 95%, and 97% for WS2/Bi2O2Se, 0.4 at.% V‐WS2/Bi2O2Se, and 2 at.% V‐WS2/Bi2O2Se, respectively, indicating a superior charge transfer in V‐WS2/Bi2O2Se compared to pristine WS2/Bi2O2Se. The exciton binding energies for WS2/Bi2O2Se, 0.4 at.% V‐WS2/Bi2O2Se and 2 at.% V‐WS2/Bi2O2Se heterostructures are estimated to be ≈130, 100, and 80 meV, respectively, which is much lower than that for monolayer WS2. These findings confirm that by incorporating V‐doped WS2, charge transfer in WS2/Bi2O2Se heterostructures can be tuned, providing a novel light‐harvesting technique for the development of the next generation of photovoltaic devices based on V‐doped transition metal dichalcogenides (TMDCs)/Bi2O2Se.more » « less
