Monolithic Photoelectrochemical Device for 19% Direct Water Splitting

TL;DR

This paper presents a monolithic photoelectrochemical device achieving over 19% solar-to-hydrogen efficiency by optimizing surface reflectivity, catalyst layers, and protective coatings, advancing the prospects for efficient solar water splitting.

Contribution

The authors develop a novel monolithic device architecture with integrated corrosion protection and catalyst layers, achieving high efficiency in solar water splitting.

Findings

Achieved 19.3% solar-to-hydrogen efficiency in acidic electrolyte.

Achieved 18.5% efficiency at neutral pH under simulated sunlight.

Reduced surface reflectivity and parasitic absorption through design improvements.

Abstract

Recent rapid progress in efficiencies for solar water splitting by photoelectrochemical devices has enhanced its prospects to enable storable renewable energy. Efficient solar fuel generators all use tandem photoelectrode structures, and advanced integrated devices incorporate corrosion protection layers as well as heterogeneous catalysts. Realization of near thermodynamic limiting performance requires tailoring the energy band structure of the photoelectrode and also the optical and electronic properties of the surface layers exposed to the electrolyte. Here, we report a monolithic device architecture that exhibits reduced surface reflectivity in conjunction with metallic Rh nanoparticle catalyst layers that minimize parasitic light absorption. Additionally, the anatase TiO2 protection layer on the photocathode creates a favorable internal band alignment for hydrogen evolution. An initial solar-to-hydrogen efficiency of 19.3 % is obtained in acidic electrolyte and an efficiency of 18.5 % is achieved at neutral pH condition (under simulated sunlight).