Efficient Direct Solar-to-Hydrogen Conversion by In Situ Interface Transformation of a Tandem Structure

TL;DR

This paper presents a novel in situ interface transformation technique for tandem photoelectrodes that significantly enhances solar-to-hydrogen efficiency, surpassing current benchmarks and enabling robust, high-performance artificial photosynthesis systems.

Contribution

It introduces a chemical surface transformation method that improves interface quality and efficiency of tandem photoelectrodes for direct solar-to-hydrogen conversion.

Findings

Achieved a solar-to-hydrogen efficiency of 14%.

Photocurrent approaches the theoretical limit of the absorber.

Surpassed existing benchmarks for integrated systems.

Abstract

Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilises customised tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here, a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalisation procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.