Efficient and stable MoS2 catalyst integrated on Si photocathodes by photoreduction and post-annealing for water splitting

Abstract

MoS2 has been studied as an efficient and cheap hydrogen evolution reaction (HER) catalyst; however, its effective integration with a photocathode remains a challenge. Here, crystalline MoS2 catalyst was deposited on top of a ∼2 nm Al2O3 protected n+p-Si photocathode using a simple photoreduction method following a post-annealing. The amount of MoS2 is optimized for HER of the photocathode, balanced between its catalytic effect and light absorption. High efficiency with 0.35 V onset potential vs. reversible hydrogen electrode and 34.5 mA/cm2 saturated photocurrent and high stability after 2 min ultrasonication or under 40 h continuous HER were observed. Such properties are much superior to the corresponding photocathodes coated by the traditional electrodeposited amorphous MoS2. Furthermore, the MoS2 layer is also an effective support for Pt nanoparticles with considerable reduction in the Pt amount while keeping the photoelectrochemical reactivity. This study indicates that the cheap-made MoS2 can be an efficient and stable HER catalyst for the Si photocathode.