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

Photoelectrochemical carbon dioxide conversion to fuels such as carbon monoxide, methanol, and ethylene exhibits great potential to solve energy issues. Unfortunately, CO₂ conversion efficiency is still low due to violent charge recombination at the photoanode. Herein, a novel 3D macroporous ferroelectric heterojunction composed of BiFeO₃ and LiNbO₃ is developed by a template-assisted sol-gel method, aiming at facilitating charge transfer kinetics. As expected, a tremendous enhancement of photocurrent density (300 times vs bare planar BiFeO₃ film) and charge transfer efficiency (up to 76%) is obtained in the HCO₃ ^- /CO₂ system without any cocatalyst. The photoelectrochemical performance is switchable by poling to form a depolarization electric field. Photoelectrochemical impedance spectroscopy reveals that the charge transfer resistance decreases due to the synergistic effect of BiFeO₃ 3D macroporous skeleton and LiNbO₃ passivation layer by tuning surface states. These results suggest a novel strategy for enhancing photoelectrochemical water oxidation as the anodic reaction of CO₂ reduction.

Plasmonic enhanced Cu2O-Au-BFO photocathodes for solar hydrogen production

A novel Cu₂O-Au-BFO heterostructure photocathode was constructed which significantly improved the efficiency of photo-generated carrier transfer for solar hydrogen production. A BiFeO₃ (BFO) ferroelectric film was synthesized on top of a Cu₂O layer by a sputtering process. The BFO layer acted to protect the Cu₂O layer from photochemical corrosion, increasing photoelectrochemical (PEC) stability. The p–n heterojunction between Cu₂O and BFO layers enhanced the PEC properties by suppressing charge recombination and improved interfacial charge transfer efficiency. When Cu₂O and BFO are interfaced by Au Nanoparticles (NPs) the PEC performance was further enhanced, due to hot-electron transfer at the plasmonic resonance. After positive poling, the depolarization field across the whole volume of BFO film drove electrons into the electrolyte solution, inducing a significant anodic shift, V_op of 1.01 V vs. RHE, together with a significantly enhanced photocurrent density of −91 μA/cm² at 0 V vs. RHE under 100 mW/cm² illumination. The mechanism was investigated through experimental and theoretivcal calculations.

Improved photocathodic performance in Pt catalyzed ferroelectric BiFeO3 films sandwiched by a porous carbon layer

A porous carbon buffer layer loaded with Pt is very effective for enhancing the solar-driven H₂ production by the ferroelectric BiFeO₃ film.