Zn<sub>0.5</sub>Cd<sub>0.5</sub>Se Embedded CuS 0D/2D\nS‑Scheme Heterojunction for Surface-Plasmon-Resonance Enhanced\nPhotocatalytic H<sub>2</sub>O<sub>2</sub> Production and <i>para</i>-Ni

Artificial photosynthesis has ignited the spark for significant\nhydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) formation owing to\nits environmental sustainability and cost-effectiveness; however,\nlimited light absorption potential and sluggish charge separation/migration\nhinder the overall photocatalytic efficiency. To overcome this, a\nheterostructure of point-to-face S-scheme heterojunction integrated\nwith the surface plasmon resonance (SPR) effect is demonstrated to\nexhibit high performance. Herein, we synthesized zero-dimensional\nZn<sub>0.5</sub>Cd<sub>0.5</sub>Se (ZCSe) QDs decorated on CuS (CS)\nnanosheets through a two-step pathway. The optimized composite CZ2\nexhibited a significant photocatalytic H<sub>2</sub>O<sub>2</sub> production\n(PHPP) rate of 3.73 mmol g<sup>–1</sup> h<sup>–1</sup> in the presence of ethanol under visible light, which was higher\nthan that shown by their pristine components, with 0.14% solar to\nchemical conversion efficiency and surpassed the majority of sulfide/selenide-based\nphotocatalysts. Moreover, the optimum CZ2 heterostructure was exposed\nto the photocatalytic <i>para</i>-nitrophenol reduction\n(PNP) and obtained the highest 81% PNP reduction efficiency within\n120 min. The photoluminescence, Mott–Schottky analysis, XPS,\nEPR, and quenching experiments led to a better understanding of the\nmechanistic detail of photocatalytic activity and the construction\nof S-scheme heterojunction that preserved the charge carriers with\nstrong redox capacity of both ZCSe and CS. Moreover, the SPR effect\nof Cu further boosted photocatalytic performances. Furthermore, the\nloading of ZCSe QD on the CS nanosheet improved the affinity of H<sup>+</sup> owing to the more negative zeta potential, which promoted\noxygen reduction reaction for PHPP, which occurred through a two-step\nsingle electron pathway and exhibited facile stability for up to five\ncycles. This piece of work sheds light on the development of multifunctional\nphotocatalysts for the production of high-value chemicals.