In the pursuit of efficient and durable photoelectrodes for solar water splitting, Si has been extensively studied since they absorb a wide range of solar spectrum up to near infrared light, and the electrochemical potential for hydrogen evolution reaction (HER) is within their band edges. In the real situation, there is a potential barrier for the electron transfer from the band edge to the HER level, which we call overpotential. To reduce the overpotential, HER catalysts such as Pt and other noble metals are loaded on the Si surface. Due to the high cost of noble metal catalysts, a tremendous demand on developing low cost and high efficiency HER catalysts boosts studying catalytic activities of 2-dimensional (2D) transition metal disulfides (TMDs) because TMD nanomaterials such as MoS2 and WS2 have inherently large surface-to-volume ratios and possess a high density of catalytically active edge sites for HER. In this work, we have developed thermal chemical vapor deposition and sulfurization methods to grow large scalable TMD monolayer and prepare efficient photocathodes based on heterostructures of 2D TMD monolayers and p-type Si for hydrogen production. TMD monolayers play important role in HER catalysis and preventing photo-corrosion of silicon. We will show the catalytic properties of TMD monolayers, low charge transfer resistances at the solid/water interfaces caused by atomically thin TMD interlayers, and long term stability over a lengthy period of time compared with bare and noble-metal-loaded Si photocathodes.

Atomically thin transition metal disulfides on silicon for high performance water splitting photocathodes

249th National Meeting (2015)

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