Edge electron-rich carbon nitride via π-acceptor frame with high-efficient charge separation for photocatalytic hydrogen evolution and environmental remediation.

Carbon nitride (g-C3N4) has broad application prospects in photocatalytic hydrogen production, but its photocatalytic efficiency is not ideal because of the rapid recombination of photogenerated electrons and holes. Herein, we developed a green strategy to fabricate hydroxyls and carbon-bridging co-modified g-C3N4 (CCN-OH) through a one-pot copolymerization and hydrothermal treatment. Experiments and density functional theory (DFT) calculations illustrated that carbon substitution of partial bridge nitrogen can improve the degree of electron delocalization to enhance the electron supply capacity of g-C3N4, and the exsitence of the electron-withdrawing OH group induces electron migration from carbon nitride to hydroxyl group, which further improves the efficiency of photogenerated charge separation. In addition, CCN-OH possess narrower band structure, resulting in an increased visible light utilization efficiency. The as-synthesized CCN-OH9 samples displayed an excellent photocatalytic activity for degradation of tetracycline with apparent reaction rate constant (k) of 0.018 min-1 and photocatalytic hydrogen evolution of 1880.3 µmol g-1h-1, which was respectively 2.2 and 9.8 times higher than that of CN.

Nitrobenzene inarched carbon nitride nanotube drives efficient directional carriers separation for superior photocatalytic hydrogen production.

Carbon nitride (g-C3N4) is aussichtsreich for photocatalytic hydrogen evolution, but its photocatalytic activity is not ideal due to the existence of photogenerated electrons and holes in the form of excitons. Herein, a novel nitrobenzene inarched g-C3N4 nanotube photocatalyst (CN-DNP) was firstly fabricated via a facial copolymerization method. The aromatic ring in nitrobenzene could enhance the conjugation of carbon nitride to promote electron delocalization. The nitro group enabled electrons to transfer from center to the both ends of g-C3N4 nanotube, which drove the separation of photogenerated electrons and holes more effectively. Compared with bulk g-C3N4 (CN), CN-DNP had narrower bandgap that can acquire adequate visible light harvesting and improve its photocatalytic performance. Consequently, CN-DNP0.1 displayed an excellent photocatalytic H2 evolution of 2262.4 µmol g-1h-1, which was 11.2 folds higher than that of CN. This strategy provides a new guidance for constructing carbon nitride nanotube materials with carrier directional transfer to enhance the photocatalytic performance.

Sulfur/phosphorus doping-mediated morphology transformation of carbon nitride from rods to porous microtubes with superior photocatalytic activity.

Hetero-atoms doping or morphology controlling of carbon nitride (g-C3N4) can availably regulate its electronic band structure and optimize photocatalytic performance under visible light. Herein, sulful (S), phosphorus (P) co-doped porous carbon nitride microtubes (SPCN) was synthesized by using ammonium dihydrogen phosphate and melamine as precursors, in which ammonium dihydrogen phosphate can not only control the morphology of carbon nitride from nanorods to porous microtubes, but also provide a potential P source for P-doped CN. The prepared SPCN0.1 with the content of 0.1 g ammonium dihydrogen phosphate displayed the highest photocatalytic hydrogen generation rate of 4200.3 µmol g-1h-1, which was approximately 25 and 1.6 folds by bulk g-C3N4 (CN) and sulphur doped g-C3N4 microrods (SCN), respectively. Moreover, the apparent quantum efficiency of HER reached up to 10.3 % at 420 nm. The enhanced photocatalytic performance may be attributed to the synergistic effect of S, P doping and morphology structure of carbon nitride, which effectively accelerated the separation and transfer of photogenerated electron-hole pairs, proved by photoluminescence spectra, time-resolved PL spectra, electrochemical impedance spectrum and transient photocurrent responses. The novel synthetic method described in this paper is an effective approach to regulate the morphology of g-C3N4via non-metal doping with superior photocatalytic performance.

Novel B-N-Co surface bonding states constructed on hollow tubular boron doped g-C3N4/CoP for enhanced photocatalytic H2 evolution.

Graphitic carbon nitride (g-C3N4) is a promising photocatalyst for water hydrogen evolution. Nonetheless, fast recombination of photogenerated electron-hole pairs and the slow kinetics of hydrogen production result in the unsatisfactory efficiency of solar hydrogen production. we address this issue by anchoring the cobalt phosphide (CoP) cocatalyst onto the one-dimensional boron doped g-C3N4 nanotube (B-CNNT) to construct B-N-Co surface bonding states in the B-CNNT/CoP photocatalyst. Spectroscopic measurement and density functional theory (DFT) calculations demonstrated that the B-N-Co bonds optimize the local electronic distribution of bonded Co and adjacent P atoms, strengthen the electrons' delocalization capacity of Co atoms for high electrical conductivity and accelerate the photogenerated carrier transfer between B-CNNT and CoP, which lead to the enhanced photocatalytic activity of the B-CNNT/CoP photocatalyst for hydrogen evolution. B-CNNT/CoP-2.45% achieved a remarkable photocatalytic hydrogen production rate of 784 µmol g-1h-1 with an apparent quantum efficiency of 5.32% at 420 nm, which is significantly higher than demonstrated by CNNT/CoP-2.45% (153 µmol g-1h-1). Our findings provide insights into as well as establish theoretical and practical grounds for the development of low-cost, high-performance photocatalytic materials for hydrogen evolution.

Self-assembly of emissive metallocycles with tetraphenylethylene, BODIPY and terpyridine in one system.

Tetraphenylethylene (TPE) related (supra)molecules have been intensively investigated due to their aggregation-induced emission (AIE) effect based on the restriction of intramolecular rotation (RIR). Meanwhile, boron-dipyrromethene (BODIPY) tends to emit intense fluorescence with high quantum yields. Herein, we combined TPE, BODIPY and terpyridine (TPY) into one system to study the emissive behaviour of organic building block as well as a self-assembled metallo-supramolecule. The TPY and BODIPY substituents with bulky sizes provide strong hindrance to restrict the rotation of the phenyl groups on TPE, leading to enhancement of emissive properties in both solution and aggregation states. Furthermore, the BODIPY-TPE-TPY ligand (L) was assembled with Zn (II) through coordination-driven self-assembly to form a cyclic dimer (D) with typical AIE characteristics.

Highly fluorescent au nanoclusters: Electrostatically induced phase transfer synthesis for Cu2+ sensing.

This paper reports a convenient method for the synthesis of highly fluorescent Au nanoclusters (NCs) via electrostatically induced phase transfer. Furthermore, on the basis of an aggregation-induced fluorescence quenching mechanism, the potential application for Cu2+ sensing on the fluorescence emission of the Au NCs is discussed. These prepared fluorescent Au NCs offer acceptable sensitivity, high selectivity, and a limit of quantitation of 0.02 µM for the measurement of Cu2+ , which is lower than the maximum level (1 ppm, equals to 15.6 µM) of Cu2+ permitted in drinking water in China. This study contributes to the further development of practical applications with fluorescent NCs.

Gas assisted method synthesis nitrogen-doped carbon quantum dots and Hg (II) sensing.

Nitrogen-doped fluorescent carbon quantum dots (CQDs) was prepared by gas-assisted method using cellulose as precursors under ammonia atmosphere, which not only exhibited excellent photoluminescent properties, but also showed highly selective and sensitive detection of mercury ion. The nitrogen-doped CQDs displayed excitation wavelength dependent fluorescent behavior with outstanding dispersibility. Moreover, they exhibited high tolerance to various external conditions, such as storage time, pH value, and ionic strength. The rapid detection of Hg (II) by one-step operation within 1 min and the good linear correlation between I0/I and Hg (II) concentration in the range of 10-100 nM made the nitrogen-doped CQDs a promising nanoprobe for Hg (II) detection. The detection limit of the nitrogen-doped CQDs is about 7.7 nM. Such a nanoprobe has been successfully applied for the analysis of Hg (II) in natural water samples, demonstrating excellent practical feasibility.