0D/3D direct Z-scheme heterojunctions hybridizing by MoS2 quantum dots and honeycomb conjugated triazine polymers (CTPs) for enhanced photocatalytic performance.

Herein, a novel direct Z-scheme photocatalyst was accomplished by hybridization of 0D MoS2 quantum dots (MSQDs) and 3D honeycomb-like conjugated triazine polymers (CTP) (namely, CTP-MSQD). The unique 0D/3D hierarchical structure significantly enhanced the exposure of active sites and light harvesting property, while the formed p-n junction enabled the direct strong interface coupling without the necessity of any mediators. The optimized CTP-MSQD3 exhibited continuously increased visible-light-driven photocatalytic activity and strong durability both in Cr(VI) reduction and H2 evolution, featured a rate of 0.069 min-1 and 1070 µmol/(hr∙g), respectively, which were 8 times than those of pure 3D-CTP (0.009 min-1 and 129 µmol/(hr∙g)). We believe that this work provides a promising photocatalyst system that combines a 0D/3D hierarchical structure and a Z-scheme charge flow for efficient and stable photocatalytic conversion.

Fabrication of direct Z-scheme Cu2O@V-CN (octa) heterojunction with exposed (111) lattice planes and nitrogen-rich vacancies for rapid sterilization.

The Z-scheme heterojunction has demonstrated significant potential for promoting photogenerated carrier separation. However, the rational design of all-solid Z-scheme heterojunctions catalysts and the controversies about carrier transfer path of direct Z-scheme heterojunctions catalysts face various challenges. Herein, a novel heterojunction, Cu2O@V-CN (octa), was fabricated using V-CN (carbon nitride with nitrogen-rich vacancies) in-situ electrostatic self-wrapping Cu2O octahedra. Density functional theory (DFT) calculations revealed that the separation of carriers across the Cu2O@V-CN (octa) heterointerface was directly mapped to the Z-scheme mechanism compared to Cu2O/V-CN (sphere). This is because the Cu2O octahedra expose more highly active (111) lattice planes with more terminal Cu atoms and V-CN with abundant nitrogen vacancies to form delocalized electronic structures like electronic reservoirs. This facilitates the wrapping of Cu2O octahedra by V-CN and protects their stability via tighter interfacial contact, thus enhancing the tunneling of carriers for rapid photocatalytic sterilization. These findings provide novel approaches for designing high-efficiency Cu2O-based photocatalytic antifoulants for practical applications.

GQD@NiFe-LDH Nanosheets for Photocatalytic Activity towards Textile Dye Degradation via Lattice Contraction.

The functionalized NiFe-LDH with photosensitized GQDs were synthesized through the hydrothermal route by differing the amount of GQDs solution and studied its efficacy towards the mineralization of textile dyes under visible light. The synthesized samples were characterized by XRD, FESEM, HRTEM, DRUV-Vis, RAMAN, XPS, and BET. The combined effect of the hexagonal carbon lattice in GQD and open layered porous structure of NiFe-LDH nanosheets results in the contraction of the lattice. Different reactive and conventional dyes were taken as representative dyes to evaluate the activity of the as-synthesized photocatalysts. The enhanced electron absorption/donor effect between GQDs and NiFe-LDH, and the growth of oxygen-bridged Ni/Fe-C moieties enable the composite to exhibit better photocatalytic activity. Both photocatalytic activity and characterization results confirmed that the GQD@NiFe-LDH nanocomposite heterostructure synthesized at 160 °C by taking 10 mL of GQDs aqueous solution named GNFLDH10 has a higher degree of crystallinity and has the best photocatalytic efficiency compared to other reported visible light catalysts. Specifically, the above optimized GQD@NiFe-LDH photocatalyst is capable of photo-mineralizing 50 ppm of Reactive Green in 20 min, Reactive Red in 20 min, and Congo Red in 25 min respectively following a direct Z-scheme mechanism with substantial reusability.