Surface Plasmon-Enhanced Carbon Dot-Embellished Multifaceted Si(111) Nanoheterostructure for Photoelectrochemical Water Splitting.

Because of the excellent electronic properties, Si is a well-established semiconducting material for PV technology. However, slow kinetics and a fast corroding nature make Si inefficient for the hydrogen evolution reaction (HER) in photoelectrochemical (PEC) applications. Herein, we demonstrate a multifacet Si nanowire (SiNW) decorated with surface plasmon-enhanced carbon quantum dots (AuCQDs) as efficient, stable, economical, and scalable photocathodes (PCs) for HER. The PEC performance of SiNW_AuCQDs has more than a fourfold efficiency enhancement than the pristine SiNW, which we have attributed to the combined effect of enhanced solar absorption and efficient carrier transport. The optimized PC SiNW_AuCQDs results in the highest photocurrent ∼1.7 mA/cm2, an applied bias photon-to-current conversion efficiency of ∼0.8%, and H2 gas evolution rate of ∼182.93 μmol·h-1. Furthermore, these SiNW_AuCQDs PCs provide extraordinary stability under continuous operating conditions with 1 sun illumination (100 mW/cm2). The process-line compatible fabrication process of these PCs will open a new direction at the wafer-level designing of a heterostructure for large-scale solar-fuel conversion.