A High Efficiency Si Photoanode Protected by Few-Layer MoSe2

To date, the performance of semiconductor photoanodes has been severely limited by oxidation and photo-corrosion. Here, a report is given on the use of earth-abundant MoSe2 as a surface protection layer for Si-based photoanodes. Large area MoSe2 film was grown on p(+)-n Si substrate by molecular beam epitaxy. It is observed that the incorporation of few-layer (approximate to 3nm) epitaxial MoSe2 can significantly enhance the performance and stability of Si photoanode. The resulting MoSe2/p(+)-n Si photoanode produces a light-limited current density of 30mAcm(-2) in 1M HBr under AM 1.5G one sun illumination, with a current-onset potential of 0.3V versus reversible hydrogen electrode (RHE). The applied bias photon-to-current efficiency (ABPE) reaches up to 13.8%, compared to the negligible ABPE values (<0.1%) for a bare Si photoanode under otherwise identical experimental conditions. The photoanode further produced stable voltage of approximate to 0.38V versus RHE at a photocurrent density of approximate to 2mAcm(-2) for approximate to 14h under AM 1.5G one sun illumination. This work shows the extraordinary potential of two-dimensional transitional metal dichalcogenides in photoelectrochemical application and will contribute to the development of low cost, high efficiency, and highly stable Si-based photoelectrodes for solar hydrogen production.