Photogenerated Defect‐Transit Dual S‐Scheme Charge Separation for Highly Efficient Hydrogen Production

Abstract The rational design of a step‐scheme (S‐scheme) heterojunctions in hybrid semiconductors by avoiding unwanted charge transport paths is considered as an attractive way to achieve high photocatalytic activity in hydrogen evolution reaction (HER). Here, a dual S‐scheme heterojunction formed in the lychee‐shaped W 18 O 49 /CdWO 4 /CdS nanostructures is proposed for improving the photocatalytic performance in HER under visible light irradiation. The remarkable activity in photocatalytic HER of W 18 O 49 /CdWO 4 /CdS is attributed to the unique structure and effective charge separation by the photoinduced defect‐transit dual S‐scheme mechanism and strong internal electric field. The measurements of X‐ray photoelectron spectroscopy (XPS), femtosecond transient absorption (fs‐TA) spectroscopy, and electron paramagnetic resonance (EPR) further confirm the photoinduced carrier transfer pathways following the dual S‐scheme mechanism. This research can provide a new strategy for designing the dual S‐scheme heterojunctions to improve photocatalytic performance through the defect band structure engineering.