Boosting oxygen migration via plasmons of Au nanoparticles in solar-driven solid oxide photoelectrolysis cells

Abstract

Hydrogen is a high-energy-density, clean energy storage medium, and coupling renewable energy with Solid Oxide Electrolysis Cells (SOECs) enables the sustainable production of green hydrogen. In this study, we developed solar-driven Solid Oxide Photoelectrolysis Cells (SOPCs) using a composite cathode of La_0.3Sr_0.7TiO₃ (LST) decorated with Au nanoparticles. As a widely utilized plasmonic material, Au nanoparticles deposited on the photoelectrode surface not only absorb the visible region of the solar spectrum but also trigger the Localized Surface Plasmon Resonance (LSPR) effect. Specifically, the LSPR effect induced by Au nanoparticles significantly boosts surface oxygen vacancies (O_V) and O²⁻ migration, and these processes are key for the hydrogen evolution reaction (HER). The Au-LST composite cathode exhibited a maximum photocurrent percentage of 30.37% and a photocurrent density of 75.12 mA cm⁻² under illumination. Furthermore, the cathode demonstrated excellent stability during 50 hours of alternating light–dark operation. Meanwhile, the light-enhanced mechanism of the system was systematically uncovered through electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis. This work optimizes SOPC performance and provides a new pathway for efficient solar-driven green hydrogen production.