MoS2 hydrogen evolution catalysis on p-Si nanorod photocathodes

We report on the synthesis of few−layers MoS2 flakes coated on the p−Si nanorods (p−SiNRs) via the metalorganic chemical vapor deposition (MOCVD) method. The MoS2 flakes show a vertically−standing, few−layers (10–15) morphology. The photoluminescence characteristic of the MoS2/p−SiNRs heterojunction exhibits a blue−shift energy bandgap (1.65−1.78 eV) at temperature of 77 K with thinner MoS2 layers due to the quantum confinement effect. As a result, the fabricated MoS2/p−SiNRs photocathode results in a saturated photocurrent density (PCD) and a photoconversion efficiency (η) of 42.3 mA cm−2, and 0.64% at 0 V (vs. RHE), respectively. Due to the built−in potential of heterojunction and more active edge sites, the onset voltage of the MoS2/p−SiNRs sample was positively shifted to ~0.72 V (vs. RHE). Based on this finding, we suggest that a heterojunction structure might serve an approach for fabricating the hybrid photoelectrochemical (PEC) device of the Si−based material.