Interior and Surface Synergistic Modifications Modulate the SnNb2O6/Ni-Doped ZnIn2S4 S-Scheme Heterojunction for Efficient Photocatalytic H2 Evolution

Construction of 2D S-Scheme Heterojunction Photocatalyst

Semiconductor photocatalytic technology holds immense promise for converting sustainable solar energy into chemically storable energy, with significant applications in the realms of energy and the environment. However, the inherent issue of rapid recombination of photogenerated electrons and holes hinders the performance of single photocatalysts. To overcome this challenge, the construction of 2D S-scheme heterojunction photocatalysts emerges as an effective strategy. The deliberate design of dimensionality ensures a substantial interfacial area; while, the S-scheme charge transfer mechanism facilitates efficient charge separation and maximizes redox capabilities. This review commences with a fresh perspective on the charge transfer mechanism in S-scheme heterojunctions, followed by a comprehensive exploration of preparation methods and characterization techniques. Subsequently, the recent advancements in 2D S-scheme heterojunction photocatalysts are summarized. Notably, the mechanism behind activity enhancement is elucidated. Finally, the prospects for the development of 2D S-scheme photocatalysts are presented.

Recent Advances in LDH/g-C3N4 Heterojunction Photocatalysts for Organic Pollutant Removal

Environmental pollution has been decreased by using photocatalytic technology in conjunction with solar energy. An efficient method to obtain highly efficient photocatalysts is to build heterojunction photocatalysts by combining graphitic carbon nitride (g-C3N4) with layered double hydroxides (LDHs). In this review, recent developments in LDH/g-C3N4 heterojunctions and their applications for organic pollutant removal are systematically exhibited. The advantages of LDH/g-C3N4 heterojunction are first summarized to provide some overall understanding of them. Then, a variety of approaches to successfully assembling LDH and g-C3N4 are simply illustrated. Last but not least, certain unmet research needs for the LDH/g-C3N4 heterojunction are suggested. This review can provide some new insights for the development of high-performance LDH/g-C3N4 heterojunction photocatalysts. It is indisputable that the LDH/g-C3N4 heterojunctions can serve as high-performance photocatalysts to make new progress in organic pollutant removal.

Carbon Dots as an Electron Acceptor in the ZnIn2S4@MIL-88A Heterojunction for Enhanced Visible-Light-Driven Photocatalytic Hydrogen Evolution

In this study, visible-light-responsive carbon dots (CDs)/ZnIn2S4@MIL-88A (C/ZI@ML) photocatalysts were successfully prepared through in situ loading CDs and ZnIn2S4 nanosheets on MIL-88A(Fe) to form a ternary heterojunction. The detailed characterization indicated that the two-dimensional ZnIn2S4 nanosheets were uniformly coated on the surface of MIL-88A(Fe), and ZnIn2S4/MIL-88A(Fe) exhibited enhanced photocatalytic hydrogen production performance (1259.63 μmol h-1 g-1) compared to that of pristine MIL-88A(Fe) and ZnIn2S4 under visible light illumination. After introduction of CDs into ZnIn2S4/MIL-88A(Fe), the C/ZI@ML catalyst remarkably enhanced the photocatalytic activity and the hydrogen evolution rate of 1C/ZI@ML was up to 3609.23 μmol g-1 h-1. The photoinduced charge carriers of C/ZI@ML can be efficiently separated and migrated because of the close contacted interface, synergistic effect, and suitable band structure. In combination with photoelectrochemical experiments and electron paramagnetic resonance spectra, a possible photocatalytic mechanism over C/ZI@ML was proposed. This work demonstrated a facile preparation method for fabricating efficient visible-light-driven heterojunction photocatalysts.

MOF(Fe)-derived composites as a unique nanoplatform for chemo-photodynamic tumor therapy

Fe-based metal-organic frameworks (MOFs) can be used for chemodynamic therapy (CDT) for tumors due to their unique Fenton-like effects and porous and biodegradable nature. The adsorption and transport of small molecule drugs by their structure has attracted much attention. Herein, MnO₂@NH₂-MIL101(Fe)@Ce6-F127 nanoparticles (MNMCF NPs) were synthesized using a facile solvothermal strategy. The small molecule photosensitizer Ce6 was adsorbed by MOFs to improve the biocompatibility of Ce6 and give it high bioavailability when injected intravenously. When the MNMCF NPs reached the tumor site, Fe-based MOFs exhibited Fenton-like properties, producing ˙OH and showing CDT effects. MnO₂ could specifically respond to produce O₂ in a tumor microenvironment, thereby improving the tumor hypoxia state and enhancing the efficacy of photodynamic therapy (PDT) by Ce6. Both the in vitro and in vivo experiments showed that the MNMCF-guided CDT/PDT combination therapy could effectively ablate tumors without the drawbacks of poor tolerability and potential long-term side effects. Therefore, the prepared MNMCF NPs can be used as promising candidates for synergistic CDT/PDT tumor therapy.

3D/2D Heterojunction of CeO2/Ultrathin MXene Nanosheets for Photocatalytic Hydrogen Production

Two-dimensional (2D) nanomaterials benefit from the high specific surface area, unique surface properties, and quantum size effects, which have attracted widespread scientific attention. MXenes add many members to the 2D material family, mainly metal conductors, most of which are dielectrics, semiconductors, or semimetals. With excellent electron mobility, beneficial to electron-hole separation, and large functional groups that can be tightly coupled with other materials, MXenes have broad application prospects in photocatalysis. Meanwhile, the application of CeO₂-based materials in organic catalysis, photocatalytic water splitting, and photodegradation of organic pollutants has been extensively explored, and studies have found that CeO₂-based materials show good photocatalytic performance. In view of this, we synthesized regular octahedral CeO₂ with a homojunction in one step by a hydrothermal method and compounded it with ultrathin 2D material MXene, which exhibited fast carrier migration efficiency and a good interfacial effect, making the material show excellent photocatalytic activity. The results showed that the photocatalytic H₂ evolution performance of the MXene/CeO₂ heterojunction was significantly improved. In this study, a low-cost catalyst with high photocatalytic activity was prepared, presenting a new research idea for achieving a combined 3D/2D photocatalytic system.

Cyanamide defects induced built-in electric field in crystalline carbon nitride for enhanced visible to near infrared light photocatalytic activity

Carbon nitride materials have achieved high accomplishments in solar to hydrogen energy conversion under visible light. However, the weak kinetics and rapid recombination of photogenerated charge carriers result in a...

Remarkably Improved Water Splitting Photocatalytic Performance of Crystalline TiO2 Nanobelts Hydrogenated at Atmospheric Pressure with the Assistance of Hydrogen Spillover

The unusual photocatalytic performance of hydrogenated black TiO2 has aroused worldwide interest. However, hydrogena-tion of well-crystallized TiO2 is always thought to be difficult even at rigorous conditions. In present work,...