Tunable photoelectrochemical performance of Au/BiFeO₃heterostructure

Abstract

Ferroelectric photoelectrodes, other than conventional semiconductors, are alternative photo-absorbers in the process of water splitting. However, the capture of photons and efficient transfer of photo-excited carriers remain as two critical issues in ferroelectric photoelectrodes. In this work, we overcome the aforementioned issues by decorating the ferroelectric BiFeO3 (BFO) surface with Au nanocrystals, and thus improving the photoelectrochemical (PEC) performance of BFO film. We demonstrate that the internal field induced by the spontaneous polarization of BFO can (1) tune the efficiency of the photo-excited carriers' separation and charge transfer characteristics in bare BFO photoelectrodes, and (2) modulate an extra optical absorption within the visible light region, created by the surface plasmon resonance excitation of Au nanocrystals to capture more photons in the Au/BFO heterostructure. This study provides key insights for understanding the tunable features of PEC performance, composed of the heterostructure of noble metals and ferroelectric materials.

Enhanced Photoelectrochemical Performance in Reduced Graphene Oxide/BiFeO3 Heterostructures

“…By adding more RGO nanosheets, the photocurrent density of the composite film increases and reaches a maximal value in the RGO3/BFO film (≈−90 µA cm −2 at 0 V vs Ag/AgCl). This value is higher than the current density reported for BFO epitaxial films or polycrystalline films, and also surpasses that of BFO decorated with noble‐metal Au, Ag, or Pd nanoparticle . Further increase of RGO nanosheets content leads to the reduction of photocurrent density.…”

Periodic Arrays of Diamond‐Shaped Silver Nanoparticles: From Scalable Fabrication by Template‐Assisted Solid‐State Dewetting to Tunable Optical Properties

“…Plasmonic resonances in nanoparticles, referred to as localized surface plasmon resonances (LSPRs), are among the few plasmon excitations which can be probed by direct illumination, unlike guided surface plasmon polaritons that usually require a near‐field coupling scheme of some kind. The sensitivity of LSPR at the nanoscale to particle shape and environment gives rise to countless potential applications of nanoplasmonics, such as scattering back‐reflector in photovoltaic cells, coloration, sensors (detection down to 100 femtomole concentrations), photo‐electrochemical applications like water splitting and photocatalysis, thermal plasmonics as well as perfect absorbers with film‐coupled plasmonic nanoparticles …”

Piezotronics in Photo‐Electrochemistry

“…In contrast, the −10 V poling would bend the electron energy upward at the PZT/electrolyte junction and consequently trapped the hot electron within the bulk PZT. Other than the Au/PZT case, Au/BFO, Ag/BFO, and Ag/PZT were also coupled to introduce SPR effect for improving the light absorption of ferroelectric PEC systems . These results highlight the promise of combining piezotronics with other effects (e.g., plasmonics and photonics) to synergistically bring the PEC performance to an unprecedentedly high level.…”

“…Commonly used bulk ferroelectric photovoltaic materials such as bismuth ferrite (BFO), PZT, potassium niobate (KNbO 3 ), and sodium niobate (NaNbO 3 ) can also be employed in PEC systems . Owing to the appropriate bandgap (2.2 eV), BFO is widely used as a ferroelectric PEC material.…”