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Two-dimensional graphitic carbon nitrides (2D g-C3N4) are promising photocatalysts for water splitting to hydrogen due to their non-toxicity and high stability. However, the bulk g-C3N4 has some intrinsic drawbacks, such as rapid electron–hole recombination and low charge-carrier mobility, resulting in poor photocatalytic activity. Here, 2,4-diamine-6-phenyl-1,3,5-triazine was employed as a precursor to regulating the assembly of melamine and cyanuric acid in water. The resulting g-C3N4 not only improved the visible light absorption and electron–hole separation but also provided more catalytic sites for enhanced photocatalytic hydrogen evolution. The modified g-C3N4 (CNP10-H) showed a hydrogen-releasing rate of 2184 μmol·g−1·h−1, much higher than the bulk g-C3N4. [ABSTRACT FROM AUTHOR]

• QDs can encapsulate by single-step, multistep, ultrasonic and solvothermal methods. • Encapsulated QDs in ZIF-8, enhanced fluorescence & stability with alter morphology. • QDs@ZIF-8 sensors widely used in biological, chemical, and environmental analysis. • QDs@ZIF-8 also used for high sensitivity and selectivity in analysis. Semiconducting quantum dots, with particle sizes ranging from 1-10nm, have unique photophysical and electronic properties with a wide range of applications. However, their instability and tendency to agglomerate profoundly affect their activity and hence their applications. To address this issue, QDs have been modified with Zeolite imidazole framework (ZIF-8), a metal-organic framework (MOF), which provides high specific surface area, stability, and structural conformations. The modification not only positively affected the band gap of ZIF-8 by narrowing it down but also enhanced the fluorescence and stability of QDs. This in turn outstretched the applications of the QDs@ZIF-8 nanocomposite across various fields like catalysis, drug delivery, LEDs and sensors along with others. QDs@ZIF-8 serves as magnificent environmental remediator by degrading the environmental pollutants through photocatalytic redox reactions and are potential candidates for the targeted drug delivery due to their high porosity and loading capacity. The outcomes of various studies highlighted increased electron-hole pair separation upon irradiation with efficient charge transfer which resulted in high PLQY in LEDs (86%), amplified photocatalytic activity (85%) in catalysis and improved sensitivity (min LOD of about 8.9×10−10) and selectivity in sensors. The purpose of this article is to pinpoint the significance of QDs@ZIF-8 nanocomposite along with clearly stating the gaps in the existing studies that would stimulate the scientists and researchers to investigate the field of QDs@ZIF-8 to the best of their knowledge and contribute to the existing literature. [Display omitted] [ABSTRACT FROM AUTHOR]

The vacuum tube method has been used for the construction of nondestructive and physically stable graphitic carbon nitride/graphene nanoplatelet composites and their photocatalytic behavior studied by measuring different photoactivities, such as photocurrent, photoluminescence, and the photodegradation of tetracycline hydrochloride under visible‐light irradiation. The formation of a heterojunction was confirmed by XRD, TEM, SEM, FTIR, XPS, and Raman spectroscopy. The results of this research indicate that the vacuum tube method is a facile, economic, and environmentally friendly approach to the preparation of composites. An ion‐trapping experiment indicated that, under visible light, the most effective photocatalyst generated the superoxide radical (O2·–) and holes (h+) to achieve the complete degradation of tetracycline hydrochloride. [ABSTRACT FROM AUTHOR]

This study focused on the fabrication of a peculiar 3D/2D ZnIn 2 S 4 /oxygen-doped graphitic carbon nitride (ZnIn 2 S 4 /SO-GCN) through a simple hydrothermal method. The flower-like morphology of hexagonal ZnIn 2 S 4 disperse on the SO-GCN nanosheets are evidenced by XRD, scanning and transmission electron microscopy. The as-synthesized nanocomposites were intensively applied for the visible light photocatalytic removal of aqueous phase 2,4-D. The heterojunction creation and the well-developed combined interface between ZnIn 2 S 4 and SO-GCN significantly increases its photogenerated charge separation capability. The photo-degradation mechanism disclose that the heterojunction has improved catalytic degradation activity, due to efficient transferring of photogenerated electron-holes pairs. Under visible-light irradiation, these nanocomposites showed 3–5 times higher degradation rate of 2,4-D (i.e. 0.0112/min, by 30%-ZnIn 2 S 4 /SO-GCN), as compared to solo ZnIn 2 S 4 and SO-GCN, attributed to the composite's synergistic effect in unique 3D/2D heterojunction, that accelerates the electron-hole separation. The h+ and •OH species contribute a noteworthy role in the degradation process of 2,4-D over 30%-ZnIn 2 S 4 /SO-GCN. In addition, the synthesized nanocomposites sustained their reusability performance in five cyclic run. Our research have implications of constructing 3D/2D nanocomposites which is beneficial for scalable solution of efficient photocatalysts. • Flower like ZnIn 2 S 4 /SO-GCN heterojunction was synthesized by hydrothermal method. • Interfacial microstructures significantly enhanced the photocatalytic performance. • A typical Type II heterostructure was confirmed between SO-GCN and ZnIn 2 S 4. • The degradation rate of 2,4-D by 30%-ZnIn 2 S 4 /SO-GCN was investigated. [ABSTRACT FROM AUTHOR]

• Novel tetrabutyl titanate-directed single-unit-cell Ti-doped Bi 2 WO 6 was fabricated by facile hydrothermal method. • The Ti-doping mediate crystal defects and generate surface oxygen vacancies, improving the visible light absorption. • The Ti-doping can act as surface electron scavenger sites, which enhanced the charge transfer and suppress the recombination rate. • The synergistic effect of Ti-doping and surface oxygen vacancies greatly enhance the photocatalytic performance of Ti-Bi 2 WO 6 compared Bi 2 WO 6. • A possible photodegradation pathway for ceftriaxone sodium was proposed and discussed. Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi 2 WO 6 crystal lattice via varying content of Ti dopant to fabricate single-unit-cell layered structure, resulting in enhanced visible-light-driven photocatalytic efficiency. Density functional theory (DFT) calculations verified that the substitution of Bi cation in the crystal structure of Bi 2 WO 6 can induce a new defect level, and increase the density of states (DOS) at the valence band maximum, which not only improve the charge dynamic but also the electronic conductivity. Remarkably, the single-unit-cell layers Ti-doped Bi 2 WO 6 structure casts profoundly improved photocatalytic performance towards ceftriaxone sodium degradation, Cr(VI) reduction, and particularly higher photocatalytic H 2 production rate, with a 5.8-fold increase compared to bulk Bi 2 WO 6. Furthermore, the photoelectrochemical measurements unveil that the significantly higher charge migration and charge carrier dynamic counts for the elevated photocatalytic performance. After careful examination of experimental results, it was proved that the Ti doping mediated crystal defects, and engendered oxygen vacancies are critically important for controlling the photocatalytic performance of Bi 2 WO 6. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interface α-MnO 2 /Bi 2 WO 6 heterostructure synthesized with abundant Mn3+/Mn4+ defect. • Boosted visible light by surface oxygen vacancies, defects sites. • O 2 − and 1O 2 were the main ROS for TC-HCl degradation, Cr6 reduction. • DFT calculation reveals high charge density at the built-in-interface. • Mechanistic insights into Z-scheme charge transfer. The construction of visible-light-driven hybrid heterostructure photocatalysts is of great significance for environmental remediation, although the utilization of strong visible-light response photocatalysts with high efficiency and stability remains a major challenge. On the other hand, defect engineering is an excellent way to introduce metal cation vacancies in materials, thereby ensuing in highly enhanced catalytic performance. Inspired by this, we effectively constructed a built-in interface α-MnO 2 /Bi 2 WO 6 heterostructure with abundant intimate interfaces and defective Mn3+/Mn4+ active sites for photocatalytic tetracycline hydrochloride (TC-HCl), hexavalent chromium Cr6+ reduction, and Escherichia coli (E. coli) inactivation. The experimental results, such as the active species test and X-ray photoelectron spectroscopy, indicated that the defective sites Mn3+/Mn4+, surface oxygen vacancies, and Bi(3+x)+ boosted the visible light absorption, and highly enhanced the photoinduced charge separation/transfer. Furthermore, experimental and DFT calculations reveal the high charge density at the built-in interface heterostructure and the Z-scheme charge transfer mechanism during the photocatalytic process. The results further reveal that O 2 − and 1O 2 are the main reactive active species contributing to the photocatalytic reaction. The exceptional TC-HCl decomposition activity of the α-MnO 2 /Bi 2 WO 6 heterostructure (97.56%, 2.31, and 2.04 times higher than bulk), enhanced reaction kinetics (K app = 0.041 min−1, 6.4, and 5.2 times higher than bulk), removal rate of 80.3%, Cr6+ reduction to Cr3+ (98.56%, K app = 0.0599 min−1), and almost 100% bacterial inactivation compared to bulk α-MnO 2 (42.22%) and Bi 2 WO 6 (47.76%), were mainly due to the enhanced charge separation/transfer at the built-in interface and high charge density. This study opens new horizons for constructing Z-scheme MnO-based interface heterostructures with abundant defect sites for exceptional photocatalytic applications. [ABSTRACT FROM AUTHOR]

Graphical abstract The as-obtained NCNS photocatalyst both increased the absorption of visible light and exhibited more efficient charge separation compared to the precursor of 2D g-C 3 N 4. It also exhibited superior photocatalytic hydrogen evolution performance with high external quantum efficiency (∼10.7%, λ = 420 nm). Highlights • The nitrogen atoms were introduced into the 2D g-C 3 N 4 by using DMF as N source to form a novel photocatalyst (NCNS). • The NCNS both increased the absorption of visible light and exhibited more efficient charge separation. • The NCNS showed superior photocatalytic hydrogen evolution performance. Abstract The two-dimensional graphitic carbon nitride (2D g-C 3 N 4) shows excellent photocatalytic performance due to its graphene-like structure, unique electronic and optical property. However, the 2D g-C 3 N 4 suffers from lower visible light utilization because of the quantum size effect. Herein, a new approach was developed to prepare the surface nitrogen modified 2D g-C 3 N 4 nanosheets (NCNS) through a facile hydrothermal treatment route. The as-obtained NCNS exhibited a high hydrogen evolution rate of 19.8 mmol h−1 g−1 with a turnover number (TON) of 642.39 in 5 h, and the external quantum efficiency (EQE) of 10.7% at 420 nm was superior to the g-C 3 N 4 different morphological regulation. The surface nitrogen modification prompted electron delocalization of two-dimensional electron system, leading to accelerating photon-generated carrier separation and transportation efficiency. [ABSTRACT FROM AUTHOR]

A novel and highly efficient ternary mpg-C 3 N 4 /BiVO 4 /TiO 2 composite was successfully synthesized and characterized with regard to structure, chemical composition, optical properties and degradation application. The photocatalytic activities of as-prepared samples were evaluated by the photocatalytic decomposition of methylene blue (MB), practical effluent from alkylation and amination steps in 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) production. Compared with TiO 2 , BiVO 4, and mpg-C 3 N 4 , the binary composites TiO 2 /BiVO 4 and the ternary mpg-C 3 N 4 /BiVO 4 /TiO 2 composites exhibited the higher photocatalytic activity under visible light irradiation. Compared to solo mpg-C 3 N 4 and BiVO 4 , the photocatalytic efficiency of g-C 3 N 4 /TiO 2 /BiVO 4 raised up to 94%. The catalytic activity of g-C 3 N 4 /TiO 2 /BiVO 4 against TATB (alkylation and amination) also confirms its efficiency by creating intermediate which were detected by Q-TOF-MS. The thermal stability and photo-stability of the produced composites were investigated. From the view of practical application, mpg-C 3 N 4 /BiVO 4 /TiO 2 displayed superior photostability after five times recycle. The mechanism research showed the fitting of band structure among BiVO 4 , g-C 3 N 4, and TiO 2 . The presence of mpg-C 3 N 4 and BiVO 4 can notably adjust the band gap energy and the synergy effects of them can prolong the lifetime of the charge carrier. [ABSTRACT FROM AUTHOR]