Efficient n⁺p-Si photocathodes for solar H₂ production catalyzed by Co-W-S and stabilized by Ti buffer layer

Photoelectrochemical (PEC) water splitting is regarded as a promising route to produce sustainable hydrogen fuel using sunlight and water as sole inputs. Si is one of the most promising potential materials for PEC photocathode, while developing highly active non-precious catalysts and stable semiconductor/catalyst interface is critical to bring solar water splitting into reality. Herein, we reported a cheap and effective strategy based on a wet chemical method to integrate WS₂ and Co-doped WS₂ (Co-W-S) onto n⁺p-Si as noble metal−free catalysts for H₂ production. Co-W-S/n⁺p-Si photocathode exhibited much better PEC performance, resulting from the Co-W-S catalyst which has more electrochemically active sites and better electrical conductivity. A thin Ti interlayer between Co-W-S and Si was inserted to further optimize the PEC performance, especially the stability of the photocathode. As a result, an onset potential of 0.36 V vs. RHE, a photocurrent of 30.4 mA/cm² at 0 V vs. RHE and an energy conversion efficiency of 4.0% were obtained under simulated AM1.5 G illumination, along with a long-term stability for 6 days of continuous PEC reaction.