Hierarchical UiO-66(-NH₂)/CuInS₂ S-Scheme Photocatalyst with Controlled Topology for Enhanced Photocatalytic N₂ Fixation and H₂O₂ Production

The fabrication of defect rich S-scheme binary heterojunctionsystemwith enhanced space charge separation and mobilization is a pioneeringapproach for improving photoreduction efficiency towards the productionof value added chemicals. Herein, we have rationally fabricated anatomic sulfur defect-rich hierarchical UiO-66(-NH2)/CuInS2 n-p heterojunction system by uniform dispersionof UiO-66(-NH2) (UN66) nanoparticles over the surfaceof hierarchical CuInS2 nanosheets under mild conditions.The designed heterostructures are characterized by using differentstructural, microscopic, and spectroscopic techniques. The hierarchicalCuInS(2) (CIS) component shows surface sulfur defects leadingto creation of more surface exposed active sites with improved absorptionof visible light and augmented diffusion of charge carriers. The photocatalyticperformance of prepared UiO-66(-NH2)/CuInS2 heterojunction materials is explored for N-2 fixationand O-2 reduction reactions (ORR). The optimal UN66/CIS20heterostructure photocatalyst exhibited outstanding N-2 fixationand O-2 reduction performances with yields of 398 and 4073 mu mol g(-1) h(-1) under visiblelight illumination, respectively. An S-scheme charge migration pathwaycoupled with improved radical generation ability accounted for thesuperior N-2 fixation and H2O2 productionactivity. This research work furnishes a new perspective on the synergisticeffect of atomic vacancy and an S-scheme heterojunction system towardenhanced photocatalytic NH3 and H2O2 production using a vacancy-rich hierarchical heterojunction photocatalyst.