Enhanced Capability of Hydrogen Evolution Photocathode by Laminated Interface Engineering of Co/MoS QDs/pyramid-black Si.

We present a novel and stable laminated structure to enhance the performance and stability of silicon (Si) photocathode devices for photoelectrochemical (PEC) water splitting. First, by utilizing Cu nanoparticle catalysts to work on a np-black Si substrate via the metal-assisted chemical etching, we can achieve the black silicon with a porous pyramid structure. The low depth holes on the surface of the pyramid caused by Cu etching not only help enhance the light capture capability with quite low surface reflectivity (<5%) but also efficiently protect the p-n junction from damage. To improve the charge migration efficiency and mitigate parasitic light absorption from cocatalysts at the same time, we drop casted quantum dots (QDs) MoS with the size of nanometer scale as the first layer of catalyst. Hence, we then can safely electrodeposit cocatalyst Co nanoparticles to further enhance interface transfer efficiency. The synergistic effects of cocatalysts and optimized light absorption from the morphology and QDs contributed to the overall enhancement of PEC performance, offering a promising pathway for an efficient, low cost, and stable (over 100 h) hydrogen production photocathode.