Advanced plasmonic few-layered InSe nanosheet heterojunctions for enhanced photoelectrochemical water splitting

•The as-prepared ZnSe/AuNPs@InSe photoanode has pronounced photocurrent density.•Incorporating ZnSe/InSe Schottky junction with Au NPs via SPR effect enhanced spatial charge separation.•The significantly enhanced PEC performance is attributed to the exfoliated few layers 2D InSe.•The resultant heterojunction has improved charge transport, low impedance and reduced electron-hole recombination rate. The selenide-based Van der Waals heterojunctions show great potential for the next generation of photoelectronic nanodevices. Herein, we construct a 2D photoanode nanocatalyst that consists of ZnSe nanocrystals with exposed active surfaces coupled with few-layered InSe nanosheets decorated by Au nanoparticles. The resultant ZnSe/AuNPs@InSe multi-heterojunction photoanode demonstrates an outstanding photocurrent density of 4.86 mAcm−2 under AM 1.5 G simulated sunlight (100 mWcm−2), which is 8 times greater than that of the pristine InSe photoanode (0.61 mAcm−2). Moreover, the lifetime of photogenerated charge carriers is extended by a factor of 3. This significant enhancement in photoelectrochemical water splitting in the near-infrared region is attributed to the surface plasmonic effect produced by the modification of Au NPs when bulk InSe is exfoliated into multi-layered flakes. The interfacial coupling effects on carrier transfer dynamics, as revealed by impedance spectroscopy assisted with the First-Principal calculations, show that this photoanode significantly minimizes the internal resistance, boosts the charge carrier separation efficiency, and promotes water oxidation. Herein, a unique 2D photoanode nanocatalyst was constructed that consists of ZnSe nanocrystals with exposed active surfaces coupled with few-layered InSe nanosheets decorated by Au nanoparticles. The resultant ZnSe/AuNPs@InSe multi-heterojunction photoanode demonstrates an exceptionally high photocurrent density of 4.86 mAcm−2 in alkaline medium under AM 1.5 G simulated sunlight, which is 8 times higher than the pristine InSe photoanode (0.61 mAcm−2). At the same time, the lifetime of photogenerated charge carriers has also been extended 3 times. [Display omitted]