Abstract
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, Vop 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.
Highlights
Harvesting energy from solar power, via photoelectrochemical (PEC) water splitting, is an attractive solution for fulfilling the demand of renewable hydrogen energy[1]
It has been proposed that the localized surface plasmon resonance (LSPR) of noble metal nanoparticles, which are coherent oscillations of their conduction electrons, can be used to enhance the efficiency of photo-generated carriers transfer at the heterostructure interface[10,11]
Some of these energies will be high enough to tunnel into the vacant states of nearby semiconductors. (A good discussion of the dynamics of plasmons and hot electrons is given by Hartland et al.12) Injecting hot electrons in to the conduction band of semiconductors directly can prevent the impediment of the interface barrier and improve the energy band edge alignment, as reported in WS2-Au-CuInS2, ITO-Au-PZT and CdS-Au-SrTiO3 photocatalysts[23,24,25,26]
Summary
Harvesting energy from solar power, via photoelectrochemical (PEC) water splitting, is an attractive solution for fulfilling the demand of renewable hydrogen energy[1]. When the direction of Edp is from the photoelectrode to the electrolyte, the photo-generated electrons can be driven out, resulting in an increase of photocurrent density (−91 μA/cm[2] at 0 V vs RHE) and Vop of 1.01 V vs RHE under 100 mW/cm[2] illumination in 0.1 M Na2SO4 solution.
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