Nano‐Au and Ferroelectric Polarization Mediated Si/ITO/BiFeO₃ Tandem Photocathode for Efficient H₂ Production

Abstract

For efficient utilization of solar light during photoelectrochemical (PEC) water splitting, tandem photoelectrodes comprising a wider bandgap top semiconductor stacked above a smaller bandgap one have been proposed in the previous studies. However, the photocurrent is usually limited due to the blocked transfer of photogenerated carriers on the interface between the semiconductors. Here, this study constructs an Si‐pnn+/ITO/Au/BiFeO3 (BFO) hybrid photocathode catalyzed by MoS2/Pt with an intension to fulfill the efficient transfer of photogenerated electrons from Si to electrode surface. This study reveals how the local surface plasmonic resonance effect of Au nanoparticles and the depolarization electric field of BFO enhance the PEC reactivity of the photocathode, and also the catalytic effect of the combined MoS2/Pt catalyst. Remarkably, the photocathode exhibits an onset potential of 1.3 V versus reversible hydrogen electrode (RHE), and the photocurrent at 0 V versus RHE can be up to –9.1 mA cm−2 under 100 mW cm−2 Xe‐lamp illuminations. Such a unique design represents a general strategy to enhance the PEC performance of a tandem photoelectrode where the energy bands are not so matched on the interfaces, and therefore extends the scope of the tandem architectures.

Ferroelectric Materials: A Novel Pathway for Efficient Solar Water Splitting

“…The first issue is the low photocathodic current due to the rapid recombination of electron-hole pairs, which is required to achieve a better PEC performance. Another challenge is the rapid degradation during the PEC reaction [53,54]. Undoubtedly, the noble metal Pt is by far the best-performing photocathode for H 2 evolution to date [55].…”

“…More importantly, the role of TiO 2 in stabilizing the photocathode is apparent with a 10-h continuous effective PEC reaction in an acid solution. Meanwhile, most of the BFO photocathodic performance is degradable within only 2 h of continuous reaction, even when measured using the neutral Na 2 SO 4 electrolyte [53,54]. The limitation of the performance of PEC cells used BFO as photocathodes could be overcome by an interlayer TiO 2 as protection layer to avoid direct contact with its electrolyte.…”

Photocatalytic Hydrogen Production of Nd/Co Co-Doped BiFeO3 Nanoparticles With a Cellular Architecture

“…In addition, BFO has a narrow band gap (2.2 eV) and excellent chemical stability, and can be used as a photocatalyst to degrade organic pollutants and decompose water (Luo and Maggard, 2006;Li et al 2010;Cheng et al 2016). Bismuth Ferrite nanohybrids display improved photocatalytic activity and degradative ability (Fatima et al 2020;Fatima et al, 2018;Iqbal et al 2019a;Iqbal et al 2019b).…”

“…Chowdhury et al reported unassisted high-efficiency splitting of pure water using a BiFeO 3 diode (Chowdhury et al 2018). Cheng et al reported the production of hydrogen through the use of a ferroelectric polarizationmediated Si/STO/BiFeO 3 tandem photocathode (Cheng et al 2016). In this work, however, we wanted to prepare a material that could directly produce hydrogen through splitting water solely under illumination, without the use of a sacrificial agent or an external bias field.…”

Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO3−/CO2 System

“…Many strategies have been implemented to solve these problems. ⅰ) bandgap engineering, quantum dot sensitization, and LSPR for enhanced light harvesting, ⅱ) nanostructures such as nanoflake, nanowire and porous film to increase the interface area, ⅲ) passivation layer for enhanced oxidation reaction kinetics, and iv) synergistic effect of multilayer structure . On one hand, 3D macroporous (3DOM) structure, with continuous and periodical void structure and large specific surface area, provides more sites for loading catalyst and channels for electrolyte infiltration and products separation.…”