Diffuse scattering from hemispherical nanoparticles at the air-silicon interface

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.

Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes

Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.