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• Heterostructure formed between Melem and g-C 3 N 4 suppress the electron-hole rebombination. • The composite material of g-C 3 N 4 /melem by molecular engineering strategy is prepared. • The photocatalytic efficiency of g-C 3 N 4 /melem was twice as high as that of pristine g-C 3 N 4. The low efficiency of photogenerated charge separation is a critical factor to restrict the efficiency of photocatalytic reaction. Extensive research efforts have been devoted to charging kinetics to improve the efficiency of photogenerated charge separation and transfer to catalytic sites. In this research, the heterostructure and interfacial electron polarization are formed between melem and graphitic carbon nitride (g-C 3 N 4) through first-principles calculation, which can greatly suppress the electron-hole recombination. The synergistic advantage of g-C 3 N 4 /melem hybrid reveals great enhancement in photocatalytic hydrogen activity. Subsequently, we prepared the composite material of g-C 3 N 4 /melem by molecular engineering strategy, and found that the photocatalytic efficiency of g-C 3 N 4 /melem was twice of pristine g-C 3 N 4. This study provides an insightful idea to improve the efficiency of photogenerated charge separation. [ABSTRACT FROM AUTHOR]

TS-1/C3N4 composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption–desorption isotherm. The photocatalytic performance of TS-1/C3N4 composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C3N4; TS-1/C3N4-B composite (the measured mass ratio of TS-1 to C3N4 is 1:4) had best performance, with a rate constant of 0.04166 min−1, which is about two and ten times higher than those of C3N4 and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C3N4 with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C3N4 composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O2−, ·OH and h+. The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed. [ABSTRACT FROM AUTHOR]

The red emitting composite phosphors Bi 2 MoO 6 :Eu3+/C 3 N 4 were prepared via a solid-state method and characterized by different techniques like XRD, SEM, FT-IR, Raman, UV-vis DRS and PL. The effects of reaction temperature and C 3 N 4 amount on the structure and optical properties of Bi 2 MoO 6 were studied in detail. The powder X-ray diffraction patterns showed that the crystal phase structure changed with the increase of temperature. Also, the introduction of C 3 N 4 had a significant impact on photoluminescence properties, which provides a universal strategy for phosphors to improve luminescence performance. • The red emitting composite phosphors Bi 2 MoO 6 :Eu3+/C 3 N 4 are synthesized. • The emission intensity increases by about 4 times after C 3 N 4 recombination. • The enhancement mechanism of Bi 2 MoO 6 :Eu3+ is discussed in detail. [ABSTRACT FROM AUTHOR]

• Tunable mesoporous in mpg-C 3 N 4 improved the photocatalytic reduction for U(VI). • mpg-C 3 N 4 exhibited a high photocatalytic reduction efficiency to U(VI). • The photocatalytic reduction of U(VI) was highly selective to coexisting ions. • The photoconversion process of U(VI) was addressed using XPS, XRD and EXAFS. Although photocatalytic reduction has been proven to be a green, efficient, and economical strategy for uranium(VI) extraction from water, it faces several challenges, such as low quantum conversion efficiency and utilization of sunlight. In this work, the photocatalytic efficiency of g-C 3 N 4 was tuned by introducing proportionally-adjustable mesoporous. The prepared mesoporous g-C 3 N 4 samples (MCN r , r represents the initial silica/cyanamide mass ratios during synthesis) exhibited higher surface area and larger pore volume. Compared with pristine g-C 3 N 4 (BCN), both light utilization and photo-generated carrier separation efficiency were significantly improved for MCN r. MCN r showed an enhanced photocatalytic performance for the reduction of U(VI) under visible light. The optimum photocatalytic performance was achieved for MCN 1.0 , which was 6.75 times higher than that of BCN. Both transmission electron microscopy (TEM) and X-ray diffraction (XRD) have confirmed the formation of UO 2 on MCN 1.0 surface after light irradiation. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) further revealed the re-oxidation of UO 2 during the photocatalytic process. A high uranium extraction capacity (~2990 mg/g) could be achieved by MCN 1.0 , and the deposited UO 2 could be easily eluted by 0.01 mol/L Na 2 CO 3 solution after exposure to air, showing high reuse performance. In the presence of co-existing ions, the photocatalytic reduction of U(VI) remained a high selectivity. [ABSTRACT FROM AUTHOR]

Rapid detection of vanillin in food samples is important in food safety. In this work, lamellar C 3 N 4 sheets were prepared by simple pyrolysis of melamine. The as-prepared C 3 N 4 sheets were used to fabricate a vanillin electrochemical sensor. C 3 N 4 was also successfully used to modify glassy carbon electrode and exhibited excellent sensing performance. Under the optimized condition, the prepared electrochemical sensor could linearly detect vanillin between 20 nM to 10 μM and 15 μM–200 μM with a low detection limit of 4 nM. In addition, the vanillin sensor was applied to detect vanillin in milk tea and biscuits. • A high sensitive electrochemical based vanillin detection method was proposed. • A simple pyrolysis method has been proposed for graphitic carbon nitride preparation. • The electrochemical sensor has been successfully applied for vanillin detection in food sample. • Sensor should a linear vanillin detection from 20 nM to 10 μM and 15 μM–200 μM. [ABSTRACT FROM AUTHOR]

After phenanthrene contaminated soil is treated by g-C 3 N 4 under visible light, the toxicity of contaminated soil was significantly reduced. • Soil remediation method based on g-C 3 N 4 is technologically feasible. • g-C 3 N 4 can release O 2 − to degrade the phenanthrene in contaminated soil under visible light irradiation. • The toxicity of phenanthrene contaminated soil can be significantly reduced by g-C 3 N 4. An environmental-friendly soil remediation method based on the g-C 3 N 4 has been developed to remediate phenanthrene contaminated soil. g-C 3 N 4 has been synthesized by three different precursors including urea, dicyandiamide, and melamine via the conventional thermal polymerization method. Under visible light or natural sunlight, g-C 3 N 4 exhibits excellent photocatalytic activity for the degradation of phenanthrene in contaminated soil at circumneutral pH. Compared with g-C 3 N 4 synthesized by dicyandiamide and melamine, g-C 3 N 4 synthesized by urea has the highest surface areas and degradation activity of phenanthrene in soil. After phenanthrene contaminated soils were treated by g-C 3 N 4 , the ecotoxicity of soils was preliminarily evaluated by cultivating plant (lettuce) and raising earthworms (Eisenia fetida). Phenanthrene contaminated soil (200 mg/kg) exhibits obvious toxicity which the growth of lettuce has been inhibited significantly and earthworms can not even survive. Under visible light or natural sunlight, g-C 3 N 4 synthesized by three different precursors can remarkably reduce the toxicity of phenanthrene contaminated soil, which was demonstrated by the lettuce growth indexes, involving leaf length, stem length, root length, and fresh weight, and earthworms' mortality and weight loss. However, compared with the other two g-C 3 N 4 synthesized by dicyandiamide or melamine, g-C 3 N 4 synthesized by urea presents clear relative toxicity on lettuces and earthworms. [ABSTRACT FROM AUTHOR]

An efficient heterogeneous photocatalytic process coupling photocatalysis and Fenton-like process was carried out, where the Fenton-like cycle could be driven by self-produced H 2 O 2 rather than extra H 2 O 2 addition. It was revealed that C 3 N 4 por exhibited good performance at H 2 O 2 production in pure water, which was enhanced up to eight times than bare g-C 3 N 4. Fenton-like cycle was constructed in Ti3+-TiO 2 -C 3 N 4 por as C 3 N 4 por severed as H 2 O 2 donator, while the Ti3+-TiO 2 was able to provide photoinduced electrons for the Fenton-like process, resulting in the generation of much more OH radical. In addition, ESR spectra were performed to confirm the promotion of the Fenton-like cycle and much more OH radical was detected in Ti3+-TiO 2 -C 3 N 4 por than Ti3+-TiO 2 -C 3 N 4 due to the great improvement in H 2 O 2 production of C 3 N 4 por. What's more, the feasible photocatalytic mechanism of Ti3+-TiO 2 -C 3 N 4 por composite was also proposed. • An efficient self-driven heterogeneous Fenton-like process was carried out. • C 3 N 4 por was able to serve as H 2 O 2 donator. • Heterogeneous Fenton-like cycle was constructed in Ti3+-TiO 2 -C 3 N 4 por. [ABSTRACT FROM AUTHOR]

Photoelectrochemical water splitting is considered as a long-term solution for the ever-increasing energy demands. Various strategies have been employed to improve the traditional TiO2 photoanode. In this study, TiO2 nanorods were decorated by graphitic carbon nitride (C3N4) derived from different precursors such as thiourea, melamine, and a mixture of thiourea and melamine. Photoelectrochemical activity of TiO2/C3N4 photoanode can be modified by tuning the number of precursors used to synthesize C3N4. C3N4 derived from the mixture of melamine and thiourea in TiO2/C3N4 photoanode showed photocurrent density as high as 2.74 mA/cm2 at 1.23 V vs. RHE. C3N4 synthesized by thiourea showed particle-like morphology, while melamine and melamine with thiourea derived C3N4 yielded two dimensional (2D) nanosheets. Nanosheet-like C3N4 showed higher photoelectrochemical performance than that of particle-like nanostructures as specific surface area, and the redox ability of nanosheets are believed to be superior to particle-like nanostructures. TiO2/C3N4 displayed excellent photostability up to 20 h under continuous illumination. Thiourea plays an important role in enhancing the photoelectrochemical performance of TiO2/C3N4. This study emphasizes the fact that the improved photoelectrochemical performance can be achieved by varying the precursors of C3N4 in TiO2/C3N4 heterojunction. This is the first report to show the influence of C3N4 precursors on photoelectrochemical performance in TiO2/C3N4 systems. This would pave the way to explore different precursors influence on C3N4 with respect to the photoelectrochemical response of TiO2/C3N4 heterojunction photoanode. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO 2) modified g-C 3 N 4 for composite photocatalysts were fabricated by using ball-milling and calcination. The physicochemical properties of as-obtained photocatalysts were characterized by XRD, XPS, SEM, TEM, UV–vis DRS, PL and Photocurrents. The results show that the heterostructure successfully formed between TiO 2 and C 3 N 4 , and the heterostructure could effectively enhance the separation rate of the photogenerated electrons and holes. Also the positions of conduction band (CB) and valence band (VB) changed with improving the amount of TiO 2 in the as-prepared photocatalysts. The photocatalytic activities of as-prepared photocatalysts were investigated by photoreduction of CO 2 , the results exhibit that the composite photocatalysts clearly improve the photoreduction of CO 2 to CH 4 and CO. The highest yields of CH 4 and CO are of 72.2 and 56.2 μmol g−1 at an optimized modified amounts of TiO 2 under 4 h irradiation of 8 W UV lamp, respectively. The strategy of TiO 2 modified C 3 N 4 could successfully obtain effective photocatalyst for CO 2 conversion. Image 1056065 • TiO 2 modified g-C 3 N 4 composite photocatalysts were fabricated by using ball-milling method and calcination. • The positions of conduction band (CB) and valence band (VB) changed with improving the amount of TiO 2 in the composite photocatalysts. • The composite photocatalysts clearly improve the photoreduction of CO 2 to CH 4 and CO. [ABSTRACT FROM AUTHOR]

Multi-wavelength is proposed as a means to test if a new phase is truly C3N4. If it is C3N4, then the Raman modes will not disperse as the excitation wavelength changes. However, if the phase contains any π bonding, the Raman modes will disperse. [Copyright &y& Elsevier]

The interfacial charge transfer still limits the photoactivity of artificial Z-scheme photocatalysts although they showed complementary light absorption and a strong photoredox ability. In this study, layered metallene is designed as an efficient electron mediator for constructing a C 3 N 4 /bismuthene/BiOCl 2D/2D/2D Z-scheme system. This bismuthene serves as a bridge processing superior charge conductibility, abundant metal-semiconductor contact sites, and the shortened charge diffusion distance, enhancing the photocatalytic CO 2 reduction reaction activity and stability. Density functional theory calculations show that the bismuthene creates a built-in electric field and congregates interfacial electrons, which is confirmed by the stable and consistent emission of the ultrafast transient absorption spectra. This work gives new insight into the interface design of Z-scheme photocatalysts by selecting a novel metallene electron mediator.

Polymeric carbon nitride (C 3 N 4 ) is currently the most potential nonmetallic photocatalyst, but it suffers from low catalytic activity due to rapid electron-hole recombination behavior and low specific surface area. The morphology control of C 3 N 4 is one of the effective methods used to achieve higher photocatalytic performance. Here, bulk, lamellar and coralloid C 3 N 4 were synthesized using different chemical methods. The as-prepared coralloid C 3 N 4 has a higher specific surface area (123.7 m 2  · g -1 ) than bulk (5.4 m 2  · g -1 ) and lamellar C 3 N 4 (2.8 m 2  · g -1 ), thus exhibiting a 3.15- and 2.59-fold higher photocatalytic efficiency for the selective oxidation of benzyl alcohol than bulk and lamellar C 3 N 4 , respectively. Optical characterizations of the photocatalysts suggest that coralloid C 3 N 4 can effectively capture electrons and accelerate carrier separation, which is caused by the presence of more nitrogen vacancies. Furthermore, it is demonstrated that superoxide radicals (·O 2 - ) and holes (h + ) play major roles in the photocatalytic selective oxidation of benzyl alcohol using C 3 N 4 as a photocatalyst., (© 2021 IOP Publishing Ltd.)

In this work, hierarchical structure TiO 2 /hemp stem biochar carbon (HSBC) and C 3 N 4 -TiO 2 /HSBC were successfully fabricated, which were used as efficient visible-light photocatalyst degradation for ammonia nitrogen from aqueous solution. The as-prepared C 3 N 4 -TiO 2 /HSBC hybrid catalyst showed the higher efficient photocatalytic activity for decomposition of ammonia nitrogen than those of pure TiO 2 and TiO 2 /HSBC, suggesting suppressed recombination of photogenerated charges and promoted mass transfer due to synergistic effect, and thus increased photocatalytic degradation activity. The degradation of ammonia follows a pseudo-first-order kinetics. All prepared catalysts demonstrated extremely photocatalytic efficiency under visible-light and UV light illumination; the ammonia nitrogen photocatalytic degradation activity of C 3 N 4 -TiO 2 /HSBC can reach 90.3% under UV light while the degradation activity achieved about 50.7% under visible-light irradiation. The results revealed that the h + was dominantly active intermediates in the process of photocatalytic degradation. The prepared catalysts are promising for the degradation of ammonia nitrogen from water resource.

The maximum achievable N content in atom-by-atom growth of Si-C-N films is examined by combining ab initio molecular dynamics simulations in a wide range of compositions and densities with experimental data. When and only when the simulation algorithm allows the formation and final presence of N 2 molecules, the densities leading to the deepest local energy minima are in agreement with the experiment. The main attention is paid to unbonded N 2 molecules, with the aim to predict and explain the maximum content of N bonded in the amorphous networks. There are significant differences resulting from different compositions, ranging from no N 2 at the lowest energy density of a-Si 3 N 4 (57 atom % of bonded N) to many N 2 at the lowest energy density of a-C 3 N 4 (42 atom % of bonded N). The theoretical prediction is in agreement with the experimental results of reactive magnetron sputtering at varied Si+C sputter target compositions and N 2 partial pressures. A detailed analysis reveals that while there is a relationship between the N 2 formation and the packing factor, which is valid in the whole compositional range investigated, the lowest-energy packing factor depends on the composition. The results are important for the explanation of experimentally reported maximum N contents, design of technologically important amorphous nitrides and pathways of their preparation, prediction of their stability, and identification of what may or may not be achieved in this field.

TS-1/C 3 N 4 composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption-desorption isotherm. The photocatalytic performance of TS-1/C 3 N 4 composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C 3 N 4 ; TS-1/C 3 N 4 -B composite (the measured mass ratio of TS-1 to C 3 N 4 is 1:4) had best performance, with a rate constant of 0.04166 min -1 , which is about two and ten times higher than those of C 3 N 4 and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C 3 N 4 with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C 3 N 4 composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O 2 - , ·OH and h + . The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed.

Semiconductors and metals can form an Ohmic contact with an electric field pointing to the metal, or a Schottky contact with an electric field pointing to the semiconductor. If these two types of heterojunctions are constructed on a single nanoparticle, the two electric fields may cause a synergistic effect and increase the separation rate of the photogenerated electrons and holes. Metal Ni and Ag nanoparticles were successively loaded on the graphitic carbon nitride (g-C 3 N 4 ) surface by precipitation and photoreduction in the hope of forming hybrid heterojunctions on single nanoparticles. TEM/high-resolution TEM images showed that Ag and Ni were loaded on different locations on C 3 N 4 , which indicated that during the photoreduction reaction Ag + obtained electrons from C 3 N 4 in the reduction reaction, whereas oxidation reactions proceeded on Ni nanoparticles. Photocatalytic hydrogen production experiments showed that C 3 N 4 -based hybrid heterojunctions can greatly improve the photocatalytic activity of materials. The possible reason is that two heterojunctions could form a long-range electric field similar to the p-i-n structure in semiconductors. Most of the photogenerated carriers were generated and then separated in this electric field, thereby increasing the separation rate of electrons and holes. This further improved the photocatalytic activity of C 3 N 4 ., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Semiconducting heterostructures designed with rational engineering of energy bands and interfaces can accelerate electron-hole separation to boost photoelectrochemical (PEC) water splitting. Herein, InGaN nanorods (NRs)/C 3 N 4 heterojunction photoanode has been constructed by directly loading C 3 N 4 on the InGaN NRs surface through a simple chemical vapor deposition method. The working principles and interfacial charge kinetics of the heterojunction have been proposed. The unique heterojunction exhibits efficient charge separation through the potential gradient and enhanced interfacial charge transfer due to the surface passivation. Eventually, the photocurrent density of the InGaN NRs/C 3 N 4 heterojunction photoanode with loading weight ratio of 0.38% reaches up to 13.9 mA/cm2 at 1.23 V vs. RHE under an illumination of ∼100 mW/cm2, which is 2 times higher than that of the pristine InGaN NRs. The applied bias photon-to-current efficiency of the designed heterojunction can achieve as high as 2.26% at 0.9 V vs. RHE, 1.65 times higher than the bare InGaN NRs (1.37%). Moreover, the InGaN NRs/C 3 N 4 heterojunction exhibits an obviously improved stability against photocorrosion due to the efficient interfacial charge transfer. This work can open up a novel route for the rational design and construction of heterojunction based photoelectrode to readily enhance the PEC performance. [ABSTRACT FROM AUTHOR]

C 3 N 4 was used as a base semiconductor for the formation of composites with LaMO 3 (M: Co, Mn, Fe) perovskite powders prepared by sol-gel (SG) and solid-state (SS) through an easy impregnation method. The optical analysis showed a redshift displacement in the case of C 3 N 4 /LaMnO 3 and C 3 N 4 /LaCoO 3 composites due to perovskite particles act as electron traps. By photoluminescence, we elucidate that LaFeO 3 generates intermediate states inside the structure of C 3 N 4 indicating an intimate intermixing, which is also corroborated by electrochemical characterizations. The activity of the composites towards the hydrogen evolution reaction was tested under simulated solar irradiation without sacrificial agent neither noble metals. Incorporation of 2% of perovskite over C 3 N 4 showed the best efficiencies. C 3 N 4 /2%LaFeO 3 SG and C 3 N 4 /2%LaFeO 3 SS showed the highest activities (140 μmol h−1 g−1 and 40 μmol h−1 g−1 respectively). These results are attributed to the better coupling between C 3 N 4 and LaFeO 3 and the formation of a type II heterostructure. Meanwhile, the activity of C 3 N 4 /LaMnO 3 and C 3 N 4 /LaCoO 3 composites exhibited lower performance compared with composites prepared with LaFeO 3 particles, related to the creation of a type I heterostructure where the flow of charges is not efficient, limiting the photocatalytic performance. Image 1 • C 3 N 4 /LaMO 3 (M: Co, Mn, Fe) were prepared by an impregnation method. • H 2 evolution tests were performed without sacrificial agents or co-catalysts. • C 3 N 4 /2% LaFeO 3 SG exhibited the highest H 2 evolution (140 μmol g−1 h−1). • H 2 production of C 3 N 4 was 14 times improved through type II heteroestructure. • C 3 N 4 /LaCoO 3 and C 3 N 4 /LaMnO 3 show a type I heterostructure with lower efficiency. [ABSTRACT FROM AUTHOR]

A facile method was developed to prepare mesoporous graphic C3N4 (MGCN)/TiO2 composites by synthesizing MGCN through a chemical template method and combining it with TiO2 by a solvothermal route. The as-prepared nanocomposites were respectively characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and diffuse reflectance UV-vis spectroscopy (DR-UV-Vis). The specific surface areas and pore sizes of the samples were obtained by the Brunauer-Emmett-Teller (BET) method, and the photocatalytic performance of MGCN/TiO2 was evaluated by photocatalytic degradation of methyl blue (MB) aqueous solution under visible-light irradiation, with the result that the composite prepared at the MGCN/TiO2 mass ratio of 1:1 displayed a higher photodegradation, 1.85 folds and 6.72 folds of that of pure MGCN and commercial TiO2. As-prepared MGCN/TiO2 composites were utilized as coatings on the carpet tile for removing indoor HCHO and the purification efficiency of formaldehyde can reach 39.69% (24 h˙0.25 m2)−1, which was higher than that of the blank carpet with − 16.20% (24 h˙0.25 m2)−1 for self-releasing, indicating their potential application prospect in functional coatings. [ABSTRACT FROM AUTHOR]

MoS2/C3N4 (MS-CN) composite photocatalysts have been synthesized by three different methods, i.e., in situ-photodeposition, sonochemical, and thermal decomposition. The crystal structure, optical properties, chemical composition, microstructure, and electron transfer properties were investigated by X-ray diffraction, UV-vis diffuse reflectance spectroyscopy, X-ray photoelectron spectroscopy, electron microscopy, photoluminescence, and in situ electron paramagnetic resonance spectroscopy. During photodeposition, the 2H MoS2 phase was formed upon reduction of [MoS4]2− by photogenerated conduction band electrons and then deposited on the surface of CN. A thin crystalline layer of 2H MoS2 formed an intimate interfacial contact with CN that favors charge separation and enhances the photocatalytic activity. The 2H MS-CN phase showed the highest photocatalytic H2 evolution rate (2342 μmol h−1 g−1, 25 mg catalyst/reaction) under UV-vis light irradiation in the presence of lactic acid as sacrificial reagent and Pt as cocatalyst. [ABSTRACT FROM AUTHOR]

The temperature of the synthesis of bulk graphitic carbon nitride (GCN) by the polycondensation of melamine, Tp, is found to affect the structure and spectral properties of colloidal single layer carbon nitride (SLCN) nanosheets produced from the bulk GCN via the liquid‐phase exfoliation. As Tp is elevated the SLCN sheets get decorated with hydroxyl groups and become smaller due to a higher degree of destruction of the original bulk GCN. Both the size decrease and the presence of OH groups in the SLCN contribute to an increase in the photoluminescence (PL) quantum yield growing up to 56% for Tp = 700 °C. The illumination of colloidal SLCN in air‐saturated aqueous solutions results in the oxidation of nanosheets with a partial conversion of amino groups into COH groups in reactions with oxygen. The oxidation also results in the fragmentation of SLCN particles into smaller moieties and PL quenching. Oppositely, the illumination in argon‐saturated solutions results in the reduction of SLCN sheets with the formation of CC bonds between the components of adducts of SLCN with the products of a partial polyheptazine hydrolysis as well as between separate SLCN particles accompanied by the elimination of amino and hydroxyl groups. Structure and optical properties of exfoliated single‐layer carbon nitride (SLCN) are affected by the thermal regime of the synthesis of layered graphitic carbon nitride and by the post‐exfoliation photochemical treatment. Photoexcited SLCN is subjected to the oxidation and fragmentation in air‐saturated aqueous solutions, while the photoinduced reduction and coupling of SLCN nanosheets are observed in inert media. [ABSTRACT FROM AUTHOR]

Tumor hypoxia is a noteworthy impediment to effective photodynamic therapy (PDT), as it would sharply weaken the effectiveness of oxygen-dependent PDT. To enable effective PDT in both hypoxia as well as normoxia circumstances, here, we report a multifunctional nanoreactor (C 3 N 4 /MnO 2 NPs), which guarantees effective type-II PDT (oxygen-dependent) in hypoxia by in situ oxygen generation via the Fenton reaction. In addition, the C 3 N 4 /MnO 2 NPs can also be used for oxygen-independent type-I PDT by evolving the cytotoxic hydroxyl radical to reduce reliance on intracellular oxygen content. In vitro cytotoxicity assays made evident that the C 3 N 4 /MnO 2 NPs exhibit a much higher cancer-cell-killing ability than C 3 N 4 NPs not only in normoxia but also in hypoxic circumstances. The smart integration of type-I and type-II PDT into the therapeutic nanoplatform enables effective PDT even though intracellular oxygen is not satisfactory.

Photocatalytic reduction of CO 2 to renewable solar fuels is considered to be a promising strategy to simultaneously solve both global warming and energy crises. However, development of a superior photocatalytic system with high product selectivity for CO 2 reduction under solar light is the prime requisite. Herein, a series of nature-inspired Z-scheme g C 3 N 4 /FeWO 4 composites are prepared for higher performance and selective CO 2 reduction to CO as solar fuel under solar light. The novel direct Z-scheme coupling of the visible light-active FeWO 4 nanoparticles with C 3 N 4 nanosheets is seen to exhibit excellent performance for CO production with a rate of 6 μmol/g/h at an ambient temperature, almost 6 times higher compared to pristine C 3 N 4 and 15 times higher than pristine FeWO 4 . More importantly, selectivity for CO is 100% over other carbon products from CO 2 reduction and more than 90% over H 2 products from water splitting. Our results clearly demonstrate that the staggered band structure between FeWO 4 and C 3 N 4 reflecting the nature-inspired Z-scheme system not only favors superior spatial separation of the electron-hole pair in g-C 3 N 4 /FeWO 4 but also shows good reusability. The present work provides unprecedented insights for constructing the direct Z-scheme by mimicking the nature for high performance and selective photocatalytic CO 2 reduction into solar fuels under solar light.

Sodium-ion batteries (SIBs) are considered promising next-generation energy storage devices. However, a lack of appropriate high-performance anode materials has prevented further improvements. Here, a hierarchical porous hybrid nanosheet composed of interconnected uniform TiO 2 nanoparticles and nitrogen-doped graphene layer networks (TiO 2 @NFG HPHNSs) that are synthesized using dual-functional C 3 N 4 nanosheets as both the self-sacrificing template and hybrid carbon source is reported. These HPHNSs deliver high reversible capacities of 146 mA h g -1 at 5 C for 8000 cycles, 129 mA h g -1 at 10 C for 20 000 cycles, and 116 mA h g -1 at 20 C for 10 000 cycles, as well as an ultrahigh rate capability up to 60 C with a capacity of 101 mA h g -1 . These results demonstrate the longest cyclabilities and best rate capability ever reported for TiO 2 -based anode materials for SIBs. The unprecedented sodium storage performance of the TiO 2 @NFG HPHNSs is due to their unique composition and hierarchical porous 2D structure., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Efficient visible light-driven C 3 N 4 /BiOBr composite photocatalysts were prepared via a facile hydrothermal method and characterized by X-ray diffraction, Fourier transform infrared, scanning electron microscopy, UV-Vis diffuse reflectance spectra and photoluminescence spectra for the phase composition and optical property. Taking rhodamine B (RhB) as the target pollutant, the photocatalytic activity and stability of photocatalysts were studied under visible light irradiation. Furthermore, the mechanism in the process of photocatalytic degradation was discussed by electron spin resonance spectroscopy analysis and the trapping experiment of generated radicals. The results indicated that C 3 N 4 /BiOBr composite photocatalysts had excellent crystallization performance. Composited by C 3 N 4 , BiOBr exhibited considerably higher photocatalytic activity by reducing the rate of electron-hole recombination. Among prepared composites with various C 3 N 4 contents, 15% C 3 N 4 /BiOBr exhibited the best efficiency for the degradation of RhB. After irradiation for 18 minutes, the degradation rate of RhB was 100%, which was 1.5 times higher than that using pure BiOBr. The results also suggested that holes and ·O 2 - were the main reactive species in the photocatalytic process for the RhB degradation, and holes played the leading role.

We developed a universal method to prepare hydrophilic carbon nitrogen (C 3 N 4 ) nanosheets. By treating C 3 N 4 nanosheets with oxygen plasma, hydroxylamine groups (N-OH) with intense protonation could be introduced on the surface; moreover, the content of N-OH groups increased linearly with the oxygen-plasma treatment time. Thanks to the excellent hydrophilicity, uniformly dispersed C 3 N 4 solution were prepared, which was further translated into C 3 N 4 paper by simple vacuum filtration. Pure C 3 N 4 paper with good stability, excellent hydrophilicity, and biocompatibility were proved to have excellent performance in tissue repair. Further research demonstrated that the oxygen-plasma treatment method can also introduce N-OH groups into other nitrogen-containing carbon materials (NCMs) such as N-doped graphene, N-doped carbon nanotube, and C 2 N, which offers a new perspective on the surface modification and functionalization of these carbon nanomaterials.

We report herein a C3N4 templating method for successfully synthesizing defective, porous TiO2 nanosheets with Pt decoration as an efficient photocatalyst for C2H4 oxidation. During the synthetic procedure, C3N4 not only acts as a 2D template to direct synthesize porous TiO2 nanosheets (TiO2-NS) but also facilitates oxygen vacancy formation on TiO2. The resultant TiO2-NS shows enhanced UV and visible-light photoactivities toward C2H4 oxidation as compared to blank TiO2 (TiO2-B) prepared without C3N4 template. Subsquently, Pt nanoparticles are homogeneously decorated onto the surface of TiO2-NS. The as-obtained Pt-TiO2-NS exhibits efficient photocatalytic activity and stability toward ethylene oxidation.