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Double Z-scheme Bi 2 S 3 /S-CN/Bi 2 O 3 heterojunction hollow nanotubes with defective structure were synthesized and exhibited efficient photocatalytic amine oxidation owing to the synergistic of each component, hollow nanotube structure, and unique defect-transit double Z-scheme heterostructure. [Display omitted] The rational design of Z-scheme heterojunction hybrid photocatalysts is considered a promising way to achieve high photocatalytic activity. In this study, a dual Z-scheme heterojunction with bismuth sulfide (Bi 2 S 3) nanorods and bismuth oxide (Bi 2 O 3) nanoparticles anchored Sulfur-doped carbon nitride (S-CN) nanotubes (Bi 2 S 3 /S-CN/Bi 2 O 3) is designed and fabricated through the ordinal metal ion adsorption, pyrolysis, and sulfidation processes using supramolecular rods as precursor. Compared with pristine Bi 2 S 3 , Bi 2 O 3 , and CN, the dual Z-scheme tube-shaped Bi 2 S 3 /S-CN/Bi 2 O 3 catalyst exhibited a significantly improved photocatalytic activity in amine oxidation. The optimized Bi 2 S 3 /S-CN/Bi 2 O 3 nanostructure exhibits a 97.6 % benzylamine conversion and 99.4 % imine selectivity within 4 h under simulated solar light irradiation. The excellent activity of Bi 2 S 3 /S-CN/Bi 2 O 3 nanotubes can be attributed to the characteristic hollow defect band structure and efficient charge separation and transfer achieved by the dual Z-scheme charge transfer mechanism, which was systematically studied using electron spin resonance spectroscopy, Kelvin probe force microscope, and other techniques. The optimized dual Z-scheme heterojunction hybrid photocatalyst maintains the high oxidizing ability of Bi 2 S 3 and Bi 2 O 3 and the excellent reducing ability of CN, thereby significantly enhancing the photocatalytic activity. This research provides a facile and feasible synthesis strategy for designing dual Z-scheme heterojunctions with defect band structure to improve the photocatalytic activity. [ABSTRACT FROM AUTHOR]

Biomimetic heterogeneous catalysts were prepared by immobilization of meso‐tetrakis(4‐carboxyphenyl)porphyrinatomanganese(III) acetate (MnTCPP) and meso‐tetrakis(4‐carboxyphenyl)porphyrinatoiron(III) chloride (FeTCPP) on graphitic carbon nitride (g‐C3N4) nanosheets. The anchored catalysts were characterized by various techniques such as scanning electron microscopy, thermogravimetric analysis, powder X‐ray diffraction, ultraviolet visible, photoluminescence, flame atomic absorption, and Fourier transform infrared spectroscopy. The thermogravimetric analysis demonstrated that the prepared catalysts were thermally stable up to almost 350°C, exhibiting high thermal stability. In the following, the catalytic efficiency of the prepared nanocatalyst was also investigated for the oxidation of various olefins with hydrogen peroxide (as a green oxidant) and the effect of various parameters which may affect the catalytic efficiency was optimized. The maximum conversion (100% for α‐methylstyrene and 97% for cyclooctene) was obtained in the presence of MnTCPP@C3N4. The Mn porphyrin nanocatalyst shows higher catalytic efficiency compared to the Fe porphyrin. [ABSTRACT FROM AUTHOR]

Pyridinic nitrogen vacancy in carbon nitride for photo-self Fenton-like purification of organic contaminants. [Display omitted] • Carbon nitride with pyridinic nitrogen vacancy was successfully prepared. • Pyridinic nitrogen vacancy promotes charge transfer and activating O 2 into H 2 O 2. • Pyridinic nitrogen vacancy accelerates carbon nitride to adsorb organic contaminants. • Photo-self Fenton-like reaction for photocatalytic degradation of organics. This work reports a carbon nitride with pyridinic nitrogen-vacancy (N 2C V-CN), which purifies organic contaminants via an in-situ photo-self Fenton-like reaction. Experiments and calculations demonstrated that the nitrogen-vacancy induces lone-paired (LP) and symmetry-unpaired electrons, promoting the formation of low-energy LP-π hybridized orbitals and helping to overcome the pairing energy required for oxygen to accept electrons. Furthermore, the nitrogen-vacancy accelerates film and intra-particle diffusion rates of organic contaminants on N 2C V-CN, creating beneficial conditions for reactive oxide species to mineralize organic contaminants. Under sunlight and atmospheric oxygen, a photo-self Fenton-like reaction involving proton-coupled electron transfer occurred on the surface of N 2C V-CN. Furthermore, by integrating photocatalysis with flocculation, about 99.1 % suspended substance, 45.5 % chemical oxygen demand, and 38.4 % biological oxygen demand were reduced from polluted river-water. Constructing N 2C V-CN and understanding its crucial role offer theoretical and methodological insights into the in-situ purification of contaminated water bodies. [ABSTRACT FROM AUTHOR]

[Display omitted] Catalysts composed of nanocluster and single-atom (SA) were extensively used to enhance electrocatalytic water splitting performance, whereas study of their photocatalytic hydrogen (H 2) evolution activity was limited. Herein, carbon nitride (CN) decorated by ruthenium (Ru) cocatalysts existed as SA + cluster, cluster + nanoparticles (NPs), and NPs were prepared by impregnation and calcination processes. The correlation between existential form, content of Ru cocatalyst and H 2 evolution rate were carefully discussed. It was found that Ru NPs were favor for water molecule adsorption, whereas Ru SAs and clusters facilitated H 2 desorption. Theoretical calculations revealed that Ru clusters + NPs cocatalyst were beneficial for H* intermediate formation. Water splitting tests found that 1.07 wt% Ru NPs + cluster modified CN showed the highest H 2 evolution rate of 13.64 mmol h−1 g−1, which was 266.4 and 1.5 times higher than those of CN and Ru NPs (2.33 wt%) decorated CN, respectively. This work deeply reveals the influences of existential form of Ru cocatalysts on photocatalytic water splitting of CN, and provides thought in designing new cocatalysts to largely enhance H 2 evolution. [ABSTRACT FROM AUTHOR]

Pristine carbon nitride (CN) has low CO2 reduction ability due to its sluggish charge carriers transfer and CO2 activation. Herein, carbon vacancy (CV) and Ag single atoms (SAs) with N2 coordination are simultaneously introduced into CN with the ordered structure for stable and efficient photoreduction of CO2 in the presence of H2O. The optimal sample loaded with 0.053 wt.% Ag evolve 173.0 µmol g−1 CO in 3 h with 89% selectivity, which is 11.7 times higher than that of pristine CN (14.7 µmol g−1). Experiments and theoretical calculations reveal that the CV and Ag–N2 sites promote CO2 adsorption/activation and the generation of *COOH and *CO. KSCN‐assisted calcination induces more ordered arrangement of melon chains, which can accelerate charge transfer/separation and facilitate H2O oxidation, thus accounting for the largely improved CO2 photoreduction performance. This study adopts a new method to prepare Ag SA‐anchored and C‐deficient CN, and provides insights into their synergistic roles in enhancing CO2 reduction. [ABSTRACT FROM AUTHOR]

Catalytic cycloaddition of CO2 with propylene oxide (PO) is a sustainable pathway for the synthesis of propylene carbonate (PC), and the design of efficient heterogeneous catalysts is a hot research topic in both C1 chemistry and functional materials. In this work, graphitic carbon nitride (g‐C3N4) materials were prepared using urea (U) and melamine (M) as precursors through one‐step thermal condensation and then applied as catalyst supports for ZnBr2. As heterogeneous catalysts, the synthesized composites (ZnBr2/g‐C3N4‐MU) exhibited higher activity in the cycloaddition reaction of CO2 to PC than ZnBr2/g‐C3N4‐M and ZnBr2/g‐C3N4‐U. The preparation temperature of ZnBr2/g‐C3N4‐MU could affect the distributions of nitrogen species and acidic strength, which thus determined the final catalytic activity. More importantly, the loading of ZnBr2 not only introduced acidic sites but also enhanced the strength of alkaline sites of g‐C3N4‐MU, enabling ZnBr2/g‐C3N4‐MU materials as acid–base bifunctional catalysts in cycloaddition of CO2 with PO. [ABSTRACT FROM AUTHOR]

In this research, we present a novel facile, scalable, and template-free technique of synthesizing graphitic carbon nitride (g-C 3 N 4) nanotubes for generating hydrogen through photocatalysis. The hybrid technique involves a two-fold mixing of the precursor materials melamine (M) and cyanuric acid (CA), involving ball milling followed by solution mixing. By varying the M:CA molar ratios, different compositions of g-C 3 N 4 nanotubes were fabricated. The study focused on examining the surface characteristics and the photocatalytic hydrogen evolution performance of these nanotubes. Nanotubes with high specific surface area of 206 m2 g−1 for M:CA molar ratio of 1:3 and 178 m2 g−1 for M:CA molar ratio of 1:5 were produced, with H 2 evolution rates of 543 μmol h−1 g−1 and 740 μmol h−1 g−1 respectively, which were an increase of 4 and 5-fold, respectively, in comparison to the pristine sample. The enhanced efficiency of hydrogen production through photocatalysis by nanotubes, when contrasted with pristine material, can be ascribed to their high crystallinity, superior specific surface areas, decreased recombination rates of electron-hole pairs generated during light exposure, and improved dynamics of charge carriers. This hybrid technique provides a new pathway for cost-effective fabrication of g-C 3 N 4 nanotubes with substantial surface areas and high yield photocatalysts on an industrial scale, without the use of templates and hydrothermal processes for efficient hydrogen generation. [Display omitted] • Graphitic carbon nitride (g-C 3 N 4) nanotubes were synthesized using a novel hybrid synthesis technique involving dual precursor mixing. • High specific surface area g-C 3 N 4 nanotubes of ∼206 m2 g−1 and 178 m2 g−1 were achieved. • A g-C 3 N 4 nanotube with a 1:3 melamine-cyanuric acid molar ratio achieved enhanced H 2 evolution performance (740 µmol h⁻¹ g⁻¹). • The stability of g-C 3 N 4 nanotubes was shown by the consistent H 2 evolution rate during extended irradiation. [ABSTRACT FROM AUTHOR]

Tantalum oxynitride (TaON) has recently attracted much attention due to its excellent performance as a semiconductor. However, its shortage in separation of photogenerated charges hinders the wide application, which, fortunately, can be made up by forming heterojunctions with other photocatalysts. In this study, the rational design of an inorganic‐organic TaON/potassium poly (heptazine imide) (KPHI) heterojunction is reported to separate the photo charges on the two sides of this dyadic structure. The incorporation of 20 wt.% TaON into KPHI resulted not only in H2 generation but also in a wider set of environmental remediation applications under visible light, including Cr(VI) reduction and degradation of otherwise resilient antibiotics. 20TaON/KPHI effectively reduced 17.5 ppm Cr(VI) solution in 35 min under low‐power blue light irradiation with a rate constant which is ≈6 and 30 times higher than that of pristine KPHI and TaON, respectively. Moreover, the composite demonstrated a 2‐ and 40‐fold increase in H2 evolution rate in comparison to pure KPHI and TaON, respectively. This remarkable enhancement in photocatalytic activity is ascribed to the efficient electron‐hole separation and formation of an effective Z‐scheme heterojunction. This work offers a new paradigm for designing efficient photocatalytic systems for environmental applications under low‐power LED and natural sunlight. [ABSTRACT FROM AUTHOR]

[Display omitted] Despite the excellent photocatalytic activity under visible light, graphitic carbon nitride (g-C 3 N 4) exhibits a high overpotential for hydrogen evolution. To address this issue, cocatalysts have been utilized to modify g-C 3 N 4. However, the use of high-performance cocatalysts typically involves noble metals such as platinum and palladium, which are cost-prohibitive for practical applications. Therefore, the development of efficient and cost-effective cocatalysts is crucial for advancing photocatalysis. In this study, we synthesized a new Ni-based cocatalyst, nickel thiocarbonate (NiCS 3), to enhance the photocatalytic hydrogen evolution reaction (HER) on g-C 3 N 4. The NiCS 3 /g-C 3 N 4 composite demonstrated a significantly increased hydrogen evolution rate of 951 μmol·h−1·g−1 under visible light, representing more than a 105-fold improvement compared to pure g-C 3 N 4. Theoretical calculations suggested that the enhanced performance in photocatalytic hydrogen production can be attributed to the generation of a built-in electric field within the composite, facilitating efficient charge carrier separation and migration. Additionally, the C site in NiCS 3 provides a favorable Gibbs free energy of adsorbed H* (Δ G H ∗ ). This work underscores the potential of NiCS 3 as a viable alternative to precious metals in photocatalytic hydrogen production using g-C 3 N 4. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) polymeric semiconductors are a class of promising photocatalysts; however, it remains challenging to facilitate their interlayer charge transfer for suppressed in‐plane charge recombination and thus improved quantum efficiency. Although some strategies, such as π–π stacking and van der Waals interaction, have been developed so far, directed interlayer charge transfer still cannot be achieved. Herein, we report a strategy of forming asymmetric Zn−N3 units that can bridge nitrogen (N)‐doped carbon layers with polymeric carbon nitride nanosheets (C3N4−Zn−N(C)) to address this challenge. The symmetry‐breaking Zn−N3 moiety, which has an asymmetric local charge distribution, enables directed interfacial charge transfer between the C3N4 photocatalyst and the N‐doped carbon co‐catalyst. As evidenced by femtosecond transient absorption spectroscopy, charge separation can be significantly enhanced by the interfacial asymmetric Zn−N3 bonding bridges. As a result, the designed C3N4−Zn−N(C) catalyst exhibits dramatically enhanced H2O2 photosynthesis activity, outperforming most of the reported C3N4‐based catalysts. This work highlights the importance of tailoring interfacial chemical bonding channels in polymeric photocatalysts at the molecular level to achieve effective spatial charge separation. [ABSTRACT FROM AUTHOR]

Semiconductor hybrid structures containing multiple components have been considered an ideal photocatalyst design to generate long‐lived charge‐separated states. The reaction activity is highly susceptible to the catalyst component and morphology, particularly for the reactions requiring high activation energies, such as a CO2 reduction reaction (CO2RR). In this study, we selected g‐C3N4 and Cu2O as photocatalytic components having bandgaps suitable for CO2RR. Our approach involved establishing robust electric junctions between these domains by direct growth of Cu on g‐C3N4 via a polyol process. The resulting g‐C3N4/Cu2O hybrid was employed as photocatalysts in an aqueous medium without hole acceptors. The catalyst exhibited notable activities for CO (94 μmol gcat−1 h−1) and CH4 production (218 μmol gcat−1 h−1), maintaining stability for over 6 h. The inherent synergy between g‐C3N4 and Cu2O, facilitated by the formation of conductive junctions, enabled efficient electron transfer to promote CO2RR. These findings ensured the importance of junctions and interfaces in the hybrid catalyst structures for unlocking superior photocatalytic CO2RR performance. [ABSTRACT FROM AUTHOR]

Despite challenges still remain, simultaneous regulation of light absorption, carrier separation and efficient exposed active sites of carbon nitride for the photocatalytic production of hydrogen (H 2) are essential to help alleviate the energy crisis and achieve carbon neutrality. Using in-plane phenyl groups doping and interlayer sulfate groups modification, we demonstrated an eco-friendly and facile method for excogitating porous tubular graphitic carbon nitride (PhSO-TCN2.5). The PhSO-TCN2.5 has hollow tubular morphology with ultrathin pore walls, which offers more exposed active sites, shortened charge diffusion path and readily available diffusion channels. More importantly, the in-plane phenyl groups doping and interlayer sulfate groups modification enabled significant intense the visible light absorption, accelerated carrier transfer due to the electron transport channel between the interlayers. Meanwhile, PhSO-TCN2.5 possesses exceptionally adjusted band gap structure and more negative conduction band potential. Accordingly, the above synergistic effects contribute to the efficient photocatalytic efficiency in H 2 evolution to 8709.29 μmol g−1 h−1. In addition to the apparent quantum yield of 12.0% at 420 nm, that far exceeds the reported tubular and functional group-modified carbon nitride photocatalysts. This document offers guidance on designing and producing photocatalysts with high efficiency. [Display omitted] • g-C 3 N 4 with phenyl groups doping and sulfate groups modification is fabricated. • Intercalated sulfate groups facilitate the transfer and separation of charge carriers. • The tubular structure and phenyl groups contribute to improve the light absorption. • The photocatalytic H 2 evolution of PhSO-TCN2.5 is 8709.29 μmol h−1 g−1 and AQY is 12 %. • A possible photocatalytic mechanism is proposed. [ABSTRACT FROM AUTHOR]

The photocatalytic activity of 2D/2D/0D heterostructures based on few-layer black phosphorus (FLBP) g-C3N4/FLBP/Co2P in the reaction of photocatalytic hydrogen formation from an aqueous solution of triethanolamine under under visible light irradiation (400 nm) was studied for the first time. An original method for the preparation of the g‑C3N4/FLBP/Co2P composite photocatalyst is proposed, which consists of the solvothermal synthesis of cobalt phosphide Co2P nanoparticles, their immobilization on the surface of FLBP, and subsequent mixing of the FLBP/Co2P heterostructure with g‑C3N4. The synthesized photocatalysts were characterized by physicochemical analytical methods (X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission microscopy, energy-dispersive X-ray spectroscopy). The hydrogen evolution rate in the presence of the g‑C3N4/FLBP/Co2P heterostructure was 0.09 mmol h–1, which is 25 times higher than the same characteristic for the unmodified g‑C3N4 sample. The obtained numerical values of the photocatalytic activity are at the level of the literature values. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (CN) has emerged as a promising photoanodic material in water‐splitting photoelectrochemical cells (PEC). However, the current deposition methods of CN layers on substrates usually include a long heating process at 500−550 °C, which might cause sublimation or decomposition of the CN monomers and destruction of the substrate, leading to a nonuniform CN film. Herein, a simple, fast, and scalable energy‐economic procedure to synthesize homogenous CN films is introduced. The predesigned CN monomers film is subjected for several minutes to higher temperatures than the standard calcination procedure. The short heating process allows the formation of a uniform CN layer, with excellent contact with the substrate and good activity as a photoanode in PEC. The optimal CN photoanode reaches photocurrent densities of ≈200 μA cm−2 at 1.23 versus reversible hydrogen electrode in neutral and acidic solutions and 120 μA cm−2 in a basic solution. [ABSTRACT FROM AUTHOR]

In industrial production, the preparation of cubic boron nitride (cBN) under high temperature and pressure wastes a large amount of unreacted hexagonal boron nitride (hBN). This study aims to use this BN waste (wBN) as a raw material, composite it with g-C3N4 to construct wBN/g-C3N4 composites, and apply the composites in the field of photocatalysis. wBN/g-C3N4 composites were prepared by simple calcination using wBN and ammonium cyanide as raw materials. Results showed that a heterogeneous structure was formed in the composite photocatalyst, with a decrease in its bandgap width and a significant increase in its ability to absorb light. The simulated sunlight photocatalytic activity of composite photocatalysts was significantly better than that of single wBN or g-C3N4. The photocatalytic performance of B2 sample, composed of a 4:3 ratio of wBN and melamine in the raw materials, demonstrated the highest efficiency. Under simulated solar illumination, it was capable of degrading 99.3% of MB within 60 min. The experimental results with additional capture agents indicated that the main reactive species of the composite photocatalyst were superoxide radicals (·O2−) and holes (h+). [ABSTRACT FROM AUTHOR]

The present study examined potential benefits of heteroatom doping to manipulate the electrical structure and to enhance the efficiency of the sensor, with an emphasis on developing inexpensive, metal‐free electrochemical sensors. Melamine and ammonium oxalate were used as precursors in a one‐step thermal polymerization technique yielding oxygen‐doped graphitic carbon nitride (O‐gCN). Following synthesis, the material's structural and morphological properties were thoroughly examined using a multitude of analytical techniques, including EIS. A notable decrease in impedance was observed, suggesting improved conductivity. Additionally, the doping approach exhibited a noticeable improvement in reduction current receptivity and surface area as compared to unmodified graphitic carbon nitride (g‐CN). Utilizing both differential pulse voltammetry (DPV) and the classical cyclic voltammetry (CV) methods, we investigated the electro oxidation of uric acid (UA) as well as concentration dependence and selectivity studies using oxygen‐doped graphitic carbon nitride modified glassy carbon electrode (O‐gCN@GCE). O‐gCN@GCE demonstrated remarkable performance, allowing the detection of UA concentrations as low as 7.784 µAµM−1cm−2. Its low detection limit of 0.57 µM and wider linear range (5–120 µM) further highlighted its potential for extremely sensitive assays and its remarkable capacity to operate over a broad UA concentration range. [ABSTRACT FROM AUTHOR]

Solar‐driven synthesis of hydrogen peroxide (H2O2) through photocatalysis stands out as a promising avenue for sustainable energy generation, marked by environmental friendliness and industrial feasibility. However, the inherent limitations of carbon nitride (CN) in photocatalytic H2O2 production significantly impede their performance. Herein, a novel 0D/2D carbon dots‐modified CN nanosheet heterojunction (CDsMCN) is introduced, synthesized through a hydrothermal‐calcination tandem strategy induced by CDs derived from melamine. This innovative technique enhances the n→π* electronic transition in CDsMCN, accelerating the separation efficiency of electron‐hole pairs, boosting oxygen adsorption, and promoting a highly selective 2e− ORR. Comparative to pristine CN, CDs10MCN exhibited a remarkable tenfold increase in H2O2 production, reaching an impressive 1.48 mmol L−1. Furthermore, CDs10MCN demonstrates exceptional stability, maintaining its catalytic efficiency at the initial level over four consecutive cycles. The notable achievement of a molar selectivity of H2O2 ≈80% at an onset potential of 0.6 V (vs RHE) underscores its exceptional ability to produce the desired product selectively. Advanced in situ characterization together with DFT calculations revealed that the ultrathin CDs10MCN nanosheet heterojunction with enhanced n→π* electronic transition improves its optical properties, reduces bandgap, facilitates fast charge migration, and increases photocatalytic H2O2 performance, thereby serving as a promising candidate for advanced catalytic applications. [ABSTRACT FROM AUTHOR]

We present a significant advancement in the synthesis of carbon nitride framework (CN) using a rapid electric bunsen burner (EBB) method, achieving notable outcomes within a mere 10-min timeframe. The resulting material, designated as U10, exhibits amplified porosity and a semi-scrolling structure with a thickness measuring at 2.1 nm. In comparison to conventionally synthesized urea-derived carbon nitride (UCN) through a box furnace, the U10 demonstrates significantly heightened photocatalytic activity in both hydrogen (H 2) production and the removal of organic dye (methylene blue) from aqueous solutions. To ensure the robustness and reliability of this synthetic approach, two additional precursors were subjected to testing, and their rates of H 2 production were analyzed. The exceptional photocatalytic performance of the U10 material arises from its distinctive structural attributes and the synergistic influences of oxygen doping (O-doping) and the cyano (-CΞN) functional group, which are introduced during the rapid synthesis strategy. This innovative and streamlined strategy for synthesizing CN not only conserves energy and time but also significantly reduces production costs, rendering it a feasible method for the large-scale production of carbon nitride material. [Display omitted] • Developed a fast synthesis of defect-rich CN using a controlled EBB method. • Identified defect-rich CN with -CΞN groups and O, enhancing charge dynamics. • Improved charge transfer and electron-hole lifespan shown by light-dependent EPR. • Calculated thermodynamically stable structure using first-principle calculations. • Tracked intermediate products in fast CN synthesis initiated by urea. [ABSTRACT FROM AUTHOR]

The unsatisfied visible light harvesting, slow charge separation, and limited practical surface area of carbon nitride (CN) constrain its performance in photocatalytic water splitting and environmental remediation. Herein, the thermal vapor‐assisted π‐conjugation modification of CN by grafting with p‐aminophenoxy groups was developed to tune the photophysical properties of CN to enhance its photocatalytic activity. Besides extending the light absorption, the surface modification constructed a nanojunction across the depth direction, which leads to facilitated charge separation and transfer. In addition, the thermal vapor modification process thermally etches and trims the pristine CN to be a highly holey structure, resulting to >10 times increase in specific surface area. Photocatalysis results showed that the obtained modified CN yielded hydrogen from photocatalytic water splitting at a rate of 7.82 mmol/g/h, over 7‐folds as that of pristine CN, with a quantum yield of 3.28% at 400 nm. The π‐conjugation modified CN also demonstrated enhanced photocatalytic environmental remediation application, exemplified by much faster photodegradation of tetracycline hydrochloride. This work provides the thermal vapor surface chemical modification of CN as a promising integrated pathway of multiple favorable photophysical properties toward efficient photocatalysis application. [ABSTRACT FROM AUTHOR]

Creating cross‐linking to establish efficient inter‐chain charge‐transfer channels in carbon nitride represents a promising strategy for enhancing its photocatalytic capabilities. Molten salt‐assisted calcining has emerged as a method for preparing cross‐linked carbon nitrides. However, the precise influence of molten salts on the molecular structure of carbon nitride remains to be fully elucidated. Herein, we develop a KCl guided cross‐linking reaction to preliminarily reveal the formation mechanism of cross‐linking. The cross‐linking reaction is initiated by the pre‐coordination of amino groups with K+. Subsequent heating at high temperature converts the amino groups into chlorines. Then, dechlorination leads to the formation of cross‐linking. Thus, this cross‐linking reaction can be accurately described as a pre‐coordination‐induced, two‐step deamination reaction. The pre‐coordination step plays a pivotal role in the cross‐linking process. Sufficient pre‐coordination results in a relatively high cross‐linking degree of the as‐prepared CNK‐2. Consequently, CNK‐2 demonstrates a significantly enhanced photocatalytic H2O2 production, with a generation rate of 682 μmol L−1 h−1, about 59 times that of traditional carbon nitride. [ABSTRACT FROM AUTHOR]

Photocatalytic (PC) CO2 reduction reaction (CO2RR) into value‐added oxygenated products is one of the most promising ways of solving climate warming change and energy crisis simultaneously. To reach higher selectivity and productivity of fuel products, it still remains great challenge in controlling both simultaneous sequential multi‐electron/proton shuttling through different transporting pathway, which determines the intermediates and final products. Consequently, a multifunctional nickel‐perylene‐carbon nitride nanosheet (NS‐P‐g‐C3N4‐Ni) are constructed rationally to strengthen the electron and proton transfer via different pathway at the same time through molecule‐level carbon backbone with excellent conductivity/charge capacity and proton transport via pendant functional group of ‐NH2 from water oxidation sites of Ni metal cluster on perylene skeleton. CO2 adsorption is enhanced and reduction energy is reduced by the complexation of N‐atom site of NS‐P‐g‐C3N4‐Ni and adjustment of co‐planarity, optimizing conduction band and band gap with energy controllable techniques. In situ FT‐IR/Raman/EPR spectra identified and verified the transformation of active intermediates (*CO2•−, *COOH and H*COO−) adsorbed on the NS‐P‐g‐C3N4‐Ni by complexation and highly selective production of formic acid (60%) is achieved. This work sheds light on the construction of effective well‐structured sites in photocatalytic CO2 reduction to produce value‐added products with higher selectivity and productivity. [ABSTRACT FROM AUTHOR]

The local atomic environments of single‐atom photocatalysts play a decisive role in determining the solar‐to‐hydrogen energy conversion efficiency. However, controllably modulating the microstructure of single‐atom sites to enhance catalytic activity and deeply understanding the structure‐property relationship remain great challenges. Herein, electron‐rich P atoms are introduced to accurately regulate the local coordination environment and electronic configuration of Fe single atoms and construct a unique asymmetrical FeN3P2 motif into carbon nitride (FeN3P2‐CN) for significantly improving the photocatalytic H2 evolution activity and stability. Specifically, in the absence of noble metal cocatalyst and photosensitizer, the FeN3P2‐CN achieves a remarkable H2 evolution rate of 2668.5 µmol g−1 h−1 under visible light irradiation (λ > 420 nm), more than 105 times higher than that of unregulated FeN4 sample. Systematic characterizations and theoretical calculations unveil that the FeN3P2 single‐atom sites not only significantly broaden the photoabsorption region and facilitate the charge separation and interfacial transfer, but also efficiently promote adsorption and activation of H2O. This work paves a promising pathway to design novel single‐atom photocatalysts at the atomic level for achieving highly efficient water‐splitting performance. [ABSTRACT FROM AUTHOR]

Photocatalysis technology is green and sustainable for reduction of nitrobenzene to aniline. However, the photocatalytic activity of pure carbon nitride is limited by the high photogenerated carrier recombination rates. Carbon nitride nanosheets (CNN) were prepared by prepolymerization and high temperature calcination and cadmium sulfide (CdS) nanoparticles were in situ grown between the layers of carbon nitride for facilitating the separation and transfer of charges. As a result, the optimal composite catalyst (CdS/CNN‐2) exhibited superior photocatalytic activity with nitrobenzene reduction rate of 83 % within 60 min. This work presents an effective strategy for designing catalysts for the photocatalytic reduction of nitrobenzene. [ABSTRACT FROM AUTHOR]

The development of appropriate and effective periodate (PI) activation technology is currently a popular research area. This study presents a novel efficient photocatalytic activation approach of PI for pollutant degradation based on carbon nitride (g-C3N4) and visible light (Vis). The results show that the system can remove 92.3% of acid orange 7 (AO7) within 60 min under the g-C3N4/PI/Vis reaction system. The degradation rate constant (kobs) reached 4.08 × 10−2 min−1, which is 4.21, 5.16 times, and 51.3 times higher than that of the g-C3N4/Vis system (9.7 × 10−3 min−1), PI/Vis system (7.9 × 10−3 min−1) and the g-C3N4/PI system (7.96 × 10−4 min−1), respectively. Clearly, the addition of PI significantly enhances the degradation efficiency of AO7 in the system. Additionally, under the same reaction conditions, the presence of PI showed excellent oxidation capacity in the photoactivation process compared with other common oxidants, such as peroxymonosulfate, peroxydisulfate, and H2O2. Moreover, the g-C3N4/PI/Vis system showed excellent removal of AO7 across a wide range of pH levels and in the presence of various anions. Electron paramagnetic resonance (EPR) and quenching experiments suggested that the superoxide anions (•O2−) and singlet oxygen (1O2) dominated in the oxidation of pollutants in the g-C3N4/PI/Vis system. In addition, the catalyst showed relative stability during cyclic testing, although a slight reduction in degradation efficiency was observed. In brief, the g-C3N4/PI/Vis system is highly efficient and environmentally friendly, with significant application potential in wastewater treatment. [ABSTRACT FROM AUTHOR]

An open new perspective has been established toward synthesizing eco‐friendly CSA@g‐C3N4 employing surface engineering. The carbon nitride modified through camphorsulfonic acid was designed and developed in a category of the new generation of photocatalysts for the oxidation of benzyl alcohol and thioanisole in the existence of a natural deep eutectic solvent (NADES). In comparison with pure g‐C3N4, not only does CSA@g‐C3N4 exhibit an extraordinarily higher ability for harvesting visible light stemming from declining the recombination rate of electrons/holes dependent on PL results but it also reveals notable photocatalytic oxidation capability in the transformation of alcohols as well as thiols into relevant compounds. In addition, non‐metal compound (CSA) incorporation would result in considerably diminishing the energy band gap value from 2.8 to 2.28 eV to escalate the visible‐light absorption of g‐C3N4. While the conventional consensus implies that inherent properties of photocatalysts bring on high photoactivity, this study indicates that deploying choline chloride–urea deep eutectic solvent as an external factor plays the role of photoactivity accelerator. Furthermore, readily recycling and reusability can be achieved for the photocatalytic setup of CSA@g‐C3N4 ascribed to its heterogeneous nature with no drop in the photoactivity. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive evaluation of catalytic ozonation as an effective strategy for indigo dye bleaching, particularly examining the performance of four carbon-based catalysts, activated carbon (AC), multi-walled carbon nanotubes (MWCNT), graphitic carbon nitride (g-C3N4), and thermally etched nanosheets (C3N4-TE). The study investigates the efficiency of catalytic ozonation in degrading Potassium indigotrisulfonate (ITS) dye within the constraints of short contact times, aiming to simulate real-world industrial wastewater treatment conditions. The results reveal that all catalysts demonstrated remarkable decolorization efficiency, with over 99% of indigo dye removed within just 120 s of mixing time. Besides, the study delves into the mechanisms underlying catalytic ozonation reactions, elucidating the intricate interactions between the catalysts, ozone, and indigo dye molecules with the processes being influenced by factors such as PZC, pKa, and pH. Furthermore, experiments were conducted to analyze the adsorption characteristics of indigo dye on the surfaces of the materials and its impact on the catalytic ozonation process. MWCNT demonstrated the highest adsorption efficiency, effectively removing 43.4% of the indigo dye color over 60 s. Although the efficiency achieved with C3N4-TE was 21.4%, which is approximately half of that achieved with MWCNT and less than half of that with AC, it is noteworthy given the significantly lower surface area of C3N4-TE. [ABSTRACT FROM AUTHOR]

In the recent years, piezocatalysis process is attracting extensive attention as an emerging technology to remove persistent organic pollutants. Its advantage is that it relies on mechanical energy and is independent of electricity and light source, unlike electrocatalysis or photocatalysis processes. In this research, 2H-MoS2/g-C3N4 heterojunction materials were successfully fabricated via the hydrothermal method and utilized as piezocatalyst in the treatment of Rhodamine B. This material exhibited a highly efficient piezo-catalyst effect, with the piezo-response amplitudes of 78.8 mV, almost doubled compared to 39.8 mV of 2H-MoS2. The degradation of Rhodamine B by ultrasonic irradiation could reach 75.4% only after 5 s and then 94.9% in 60 s without light assistance. This ultra-rapid degradation rate is attributed to the electron–hole pairs and transfer of the charge-carriers on the surface of 2H-MoS2 and g-C3N4 via S-scheme heterojunction model, which was confirmed by density functional theory study. The piezo-catalytic ability of the material can still be improved for better treatment of other organic pollutants in aqueous environment. [ABSTRACT FROM AUTHOR]

[Display omitted] Constructing a photocatalytic in-situ Fenton system (PISFs) is a promising strategy to address the need for continuous hydrogen peroxide (H 2 O 2) addition and the low efficiency of H 2 O 2 activation for hydroxyl radical generation in the traditional Fenton reaction. In this study, we constructed a photocatalytic in-situ Fenton system using anthraquinone-modified carbon nitride (AQ-C 3 N 4) for efficient pollutant degradation. The resultant AQ-C 3 N 4 not only enhanced the production of H 2 O 2 but also increased the generation of hydroxyl radical (·OH). Experimental results demonstrated that, the apparent rate constant for the degradation of 2,4-Dichlorophenol (2,4-DCP) by AQ-C 3 N 4 -PISFs was 0.145 min−1, which is 2.74 times higher than that of C 3 N 4 under visible light. Density functional theory (DFT) calculations indicate that AQ modification promotes electron-hole separation while increasing the adsorption energy of O 2. Independent gradient model (IGM) analysis based on Hirshfeld Partition revealed that van der Waals interactions between AQ-C 3 N 4 and 2,4-DCP promoted the degradation process. This work provides new ideas to overcome the problems of continuous addition of H 2 O 2 and low utilization of ·OH that exist in conventional Fenton system. [ABSTRACT FROM AUTHOR]

The dual modified P doped crystalline carbon nitride, synthesized by molecular polymerization with salt post-treatment can significantly increase the separation of photogenerated carriers, thereby improving the photocatalytic reduction efficiency of uranyl (VI). [Display omitted] Doping modification is a useful way to promote the catalytic activity of carbon nitride (CN). However, most doped CNs have lower structural symmetry and several edge defects, which hinder the transfer of charge carriers. This work reports a P-doped crystalline carbon nitride (crystalline PCN) for the efficient photoreduction of uranyl. The thermal polymerization and salt post-treatment convert the amorphous PCN into crystalline PCN. Compared to the pristine CN, the crystalline PCN has over 1620 % higher activity for uranyl (U(VI)) reduction, reaching a 97.8 % reduction rate in 60 min. Furthermore, the 2-PCN shows excellent stability and a U(VI) removal efficiency >85.7 % in the pH range of 5–8. Characterization analysis reveal that both the P doping and crystalline modulation do not obviously change their morphology, light absorption property and energy band structure, but markedly promote the delocalization of electrons around the doped P atoms, thereby severely inhibit direct electron-hole recombination. Thus, the more efficient separation of charge carriers generates more reactive specials to participate in the photocatalytic uranyl reduction reaction. This study demonstrates a dual-modification strategy for the rational synthesis of highly active metal-free CN-based photocatalysts for uranyl reduction. [ABSTRACT FROM AUTHOR]

Graphitic‐carbon nitride (g‐C3N4), a metal‐free two‐dimensional layered semiconductor material, holds great potential for energy conversion, environmental remediation, and sensing. However, the limited solubility of g‐C3N4 in conventional solvents hinders its widespread application. Improving the dissolution of g‐C3N4 in the liquid phase is highly desired but challenging. Herein, we report an innovative approach to dissolve g‐C3N4 using ZnCl2 molten salt hydrates. The solubility of g‐C3N4 in the solution reaches up to 200 mg mL−1. Density functional theory (DFT) results suggest that ZnCl+H2O is the key species that leads to charge redistribution on g‐C3N4 surface and promotes the dissolution of carbon nitride in the solution. Furthermore, through dilution, the dissolved carbon nitride can be effectively recovered while maintaining its intrinsic chemical structure. The resultant regenerated C3N4 (r‐C3N4) exhibits nanobelt morphology and demonstrates a substantially improved photocatalytic activity in H2O2 production. The rate of H2O2 production over the r‐C3N4 reaches 20,228 μmol g−1 h−1, which is 6.2 times higher than that of pristine g‐C3N4. This green and efficient dissolution route of g‐C3N4 offers an effective approach for its diverse applications. [ABSTRACT FROM AUTHOR]

Photocatalysis is an efficient technology for the degradation of pollutants. However, there is still much room for improvement in its degradation efficiency. In this study, a pyrrolic N‐rich g‐C3N4 (PN‐g‐C3N4) framework was synthesized with transition metal M (M=Fe, Co, Ni, Cu, Cr, and Mn) atomic sites coordinated onto it. Then, a series of single atomic metals M anchored to PN‐g‐C3N4 (M/PN‐g‐C3N4) are constructed for peroxodisulfate activation. Their order of catalytic activity follows Fe>Cr>Ni>Cu≈Co>Mn, in particular the degradation rates of the TCH for Fe‐PN‐g‐C3N4 are 3.74 times higher than that of undoped PN‐g‐C3N4. These carefully regulated pyrrolic N‐rich Fe sites demonstrate outstanding performance in degrading organic pollutant. As an exemplary model, the Fe/PN‐g‐C3N4 catalyst efficiently drives the catalytic oxidation of TCH through Fenton‐like reaction under visible light, showcasing exceptional cycle stability and a broad effective pH range of 3.0–11.0. The synergy between photocatalysis and Fe doped catalysis results in increased generation and separation of charge carriers, along with the cyclic transformation of the Fe3+/Fe2+ couple. This combination significantly enhances the Fenton‐like performance, making it a highly effective process for pollutant degradation. [ABSTRACT FROM AUTHOR]

Photogenerated carriers transfer and separation from the substance itself to produce spatial isolated electron-hole pairs is crucial for the utilization of composite photocatalysts in the field of photocatalytic hydrogen (H 2) evolution. Herein, novel oxygen-doped porous graphitic carbon nitride (g-C 3 N 4) micro-sheets decorated with Ag 2 MoO 4 have been fabricated by a facile calcination method followed by in situ deposition strategy. The physicochemical properties of the obtained Ag 2 MoO 4 /OC 3 N 4 composites were characterized via SEM, TEM, EDS, XRD, N 2 adsorption-desorption, XPS, UV–vis DRS, PL, transient photocurrent response, and EIS, as well as DFT calculation. In addition, the effects of Ag 2 MoO 4 content, type of scavengers, pH value of reaction solution and dosage of scavenger on photocatalytic H 2 production were investigated. The results show that the modification of ammonium acetate thermal polymerization with urea could enhance the porosity of g-C 3 N 4 and its specific surface area. The Ag 2 MoO 4 nanoparticles are highly dispersed on the OC 3 N 4 surface, reducing the charge transfer resistance at their interfaces. The OC 3 N 4 photocatalyst achieves H 2 yield of 8629.11 μmol/g over 2 h, which is about 1.46 times higher than that of C 3 N 4. The H 2 production amount over the optimal Ag 2 MoO 4 /OC 3 N 4 composite photocatalyst (50 mg) is further enhanced to 16619 μmol/g, which is 1.93 and 180 times higher than that of OC 3 N 4 and Ag 2 MoO 4 , respectively. The S-scheme charge transfer mechanism of Ag 2 MoO 4 /OC 3 N 4 is proposed based on the DFT calculation. This work provides a facile and easy strategy to develop g–C 3 N 4 –based photocatalysts through adjusting chemical composition and photocatalytic properties. [Display omitted] • Oxygen-doped porous g-C 3 N 4 decorated with Ag 2 MoO 4 was fabricated. • Elemental sliver was generated in the photocatalytic H 2 evolution process. • Ag 2 MoO 4 /OC 3 N 4 /Pt system exhibited an excellent performance of H 2 evolution. • Construction of S-scheme mode improved the separation and transfer of carriers. [ABSTRACT FROM AUTHOR]

Carbon nitrides can form coordination compounds or metallic oxides in the presence of transition metals, depending on the reaction conditions. By adjusting the pH to basic levels for mild synthesis with metals, composites like g-C3N4-M(OH)x (where M represents metals) were obtained for nickel (II) and manganese (II), while copper (II) yielded coordination compounds such as Cu-g-C3N4. These materials underwent spectroscopic and electrochemical characterization, revealing their photocatalytic potential to generate superoxide anion radicals—a feature consistent across all metals. Notably, the copper coordination compound also produced significant hydroxyl radicals. Leveraging this catalytic advantage, with band gap energy in the visible region, all compounds were activated to disinfect E. coli bacteria, achieving total disinfection with Cu-g-C3N4. The textural properties influence the catalytic performance, with copper's stabilization as a coordination compound enabling more efficient activity compared to the other metals. Additionally, the determination of radicals generated under light in the presence of dicloxacillin supported the proposed mechanism and highlighted the potential for degrading organic molecules with this new material, alongside its disinfectant properties. [ABSTRACT FROM AUTHOR]

Carbon nitrides, metal‐free semiconducting materials, have unique molecular structure and semiconducting properties which have inspired researchers to utilize them as photocatalysts for the sustainable production of hydrogen. However, they suffer from a few drawbacks including fast charge‐carrier recombination rate and low charge transfer efficiency owing to their amorphous and less conducting wall structure which remain as significant challenge for achieving breakthrough in photocatalytic water splitting. Herein, the study reports a supramolecular approach of coupling thiourea and trimesic acid for designing highly efficient C‐doped carbon nitride photocatalysts in which the π‐electron density is precisely manipulated. The developed C‐doped carbon nitride demonstrates the fine‐tuned band positions, the mitigated electron–hole recombination, and enhanced conductivity, resulting in the facilitation of significantly enhanced hydrogen generation through the photocatalytic water splitting under the solar‐simulated light. The position and distribution of C‐doping in the carbon nitride framework are characterized by using advanced analytical techniques such as X‐ray photoelectron spectroscopy, near‐edge X‐ray absorption fine structure spectroscopy, and electron paramagnetic resonance spectroscopy together with the first‐principles studies of the electronic structure and energetics of doping. The remarkable increase in photocatalytic hydrogen generation by using developed C‐doped carbon nitride brings one step closer to achieving a green hydrogen economy. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, Br, K-doped and cyano group-rich carbon nitride (CN) were prepared via pyrolysis of molten urea and 6-Bromopyridine-3-carbaldehyde, followed by re-calcination with potassium thiocyanate. The hydrogen peroxide (H 2 O 2) evolution and in situ tetracycline (TC) mineralization performances of the prepared samples were studied. The optimal sample could produce 9127 μmol g–1 h–1 H 2 O 2 from 10 vol% ethanol solution and air atmosphere, which was 10.9 times higher than that of pristine CN. With addition of 4 mg L–1 Fe2+ ions, 97.2% of TC (10 mg L–1) and 98.7% of total organic carbon were removed in 30 min under the actions of holes, hydroxyl and superoxide radicals. The high H 2 O 2 yield and TC mineralization ratio were attributed to the increased light absorption, efficient electrons-holes separation, enhanced surface O 2 adsorption (0.3878 mmol g−1), and accelerated conversion from Fe3+ to Fe2+ ions. Meanwhile, the system possessed good reusability in H 2 O 2 evolution and TC removal. It is expected that this work can provide new ideas to design CN-based photo-Fenton system to treat wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of highly efficient oxygen evolution reaction (OER) catalysts based on more cost-effective and earth-abundant elements is of great significance and still faces a huge challenge. In this work, a series of transition metal (TM) embedding a newly-defined monolayer carbon nitride phase is theoretically profiled and constructed as a catalytic platform for OER studies. Typically, a four-step screening strategy was proposed to rapidly identified high performance candidates and the coordination structure and catalytic performance relationship was thoroughly analyzed. Moreover, the eliminating criterion was established to condenses valid range based on the Gibbs free energy of OH*. Our results reveal that the as-constructed 2FeCN/P exhibits superior activity toward OER with an ultralow overpotential of 0.25 V, at the same time, the established 3FeCN/S configuration performed well as a bifunctional OER/ORR electrocatalysis with extremely low overpotential ηOER/ηORR of 0.26/0.48 V. Overall, this work provides an effective framework for screening advanced OER catalysts, which can also be extended to other complex multistep catalytic reactions. [ABSTRACT FROM AUTHOR]

Highly-crystallized carbon nitride (HCCN) nanosheets exhibit significant potential for advancements in the field of photoelectric conversion. However, to fully exploit their potential, a thorough understanding of the fundamental excitonic photophysical processes is crucial. Here, the temperature-dependent excitonic photoluminescence (PL) of HCCN nanosheets and amorphous polymeric carbon nitride (PCN) is investigated using steady-state and time-resolved PL spectroscopy. The exciton binding energy of HCCN is determined to be 109.26 meV, lower than that of PCN (207.39 meV), which is attributed to the ordered stacking structure of HCCN with a weaker Coulomb interaction between electrons and holes. As the temperature increases, a noticeable reduction in PL lifetime is observed on both the HCCN and PCN, which is ascribed to the thermal activation of carrier trapping by the enhanced electron–phonon coupling effect. The thermal activation energy of HCCN is determined to be 102.9 meV, close to the value of PCN, due to their same band structures. Through wavelength-dependent PL dynamics analysis, we have identified the PL emission of HCCN as deriving from the transitions: σ *–LP, π *– π, and π *–LP, where the π *–LP transition dominants the emission because of the high excited state density of the LP state. These results demonstrate the impact of high-crystallinity on the excitonic emission of HCCN materials, thereby expanding their potential applications in the field of photoelectric conversion. [ABSTRACT FROM AUTHOR]

Non-woven jute (NWJ) produced from carpet industry waste was oxidized by H2O2 or alkali-treated by NaOH and compared with water-washed samples. Changes in the structure of the NWJ, tracked by X-ray diffraction (XRD), showed that both chemical treatments disrupt hydrogen bond networks between cellulose Iβ chains of the NWJ fibers. Thereafter, nano-carbon nitride (nCN) was impregnated, using a layer-by-layer technique, onto water-washed jute samples (nCN-Jw), NaOH-treated samples (nCN-Ja) and-H2O2 treated samples (nCN-Jo). Analysis of the Fourier transform infrared spectroscopy (FTIR) spectra of the impregnated samples revealed that nCN anchors to the water-washed NWJ surface through hemicellulose and secondary hydroxyl groups of the cellulose. In the case of chemically treated samples, nCN is preferentially bonded to the hydroxymethyl groups of cellulose. The stability and reusability of prepared nCN-jute (nCN-J) samples were assessed by tracking the photocatalytic degradation of Acid Orange 7 (AO7) dye under simulated solar light irradiation. Results from up to ten consecutive photocatalytic cycles demonstrated varying degrees of effectiveness across different samples. nCN-Jo and nCN-Ja samples exhibited declining effectiveness over cycles, attributed to bond instability between nCN and jute. In contrast, the nCN-Jw sample consistently maintained high degradation rates over ten cycles, with a dye removal percentage constantly above 90%. [ABSTRACT FROM AUTHOR]

A series of Ag2CrO4/g-C3N4 composites with photocatalytic hydrogen (H2) production were prepared by in-situ chemical deposition method. The phase composition, functional group structure, microscopic morphology, elemental compositions and their species of the composites were characterized using X-ray diffraction, Fourier transform infrared, field emission scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The light absorption properties and photogenerated carrier separation of the samples were investigated by UV-visible diffuse reflectance spectra, photoluminescence spectroscopy and photocurrent testing. The H2 production performance of the photocatalysts and the influencing factors were investigated experimentally. The results showed that the introduction of Ag2CrO4 did not change the originally heterocyclic structure of g-C3N4, and nanostructure Ag2CrO4 was dispersed on the surface of g-C3N4. Although Ag2CrO4 had no H2 production effect, the H2 production rate of the composite increased first and then decreased with the increase of Ag2CrO4 content. The H2 production rate of the optimal photocatalyst Ag2CrO4/C3N4-4% was 2.7 times that of pure g-C3N4. The reason was mainly attributed to the appearance of Z-type heterojunction between of Ag2CrO4 and g-C3N4, which broadened the visible light response range of g-C3N4, reduced the charge transfer impedance, and promoted the separation and migration of photogenerated carriers. [ABSTRACT FROM AUTHOR]

A comprehensive vision has been promoted for straightforward oxidative amidation, deploying a majority of amines and aldehydes via a robust and novel nano-catalyst of W/Co@g-C3N4. This approach would yield the primary, secondary, and tertiary amides with excellent efficiency experiencing mild conditions, in which the environmentally benign oxidizing agent of TBHP was predominantly used, holding remarkable attributes such as cost-effectiveness as well as facile approachability. More specifically, simultaneously embedding of W and Co on the surface of g-C3N4 has been an integral part in effectually progressing direct operation of amidation reaction in comparison with pure g-C3N4. The most important point highlighted in this work is the productive contribution of materials choice in designing as well as manufacturing approaches with respect to new required products while giving the most extreme level of accessible quality and efficiency with the most reduced level of costs. Emphatically, a variety of extraordinary merits can be awarded to this as-prepared catalyst, such as notable activity, reasonable recyclability, sustainable nature, and easy work-up. Moreover, a simple process was conducted to synthesize W/Co@g-C3N4 evaluated by employing FT-IR, XRD, SEM, EDX, and TGA. Highlights: Nano-W/Co@g-C3N4 was introduced for the first time as a robust and efficient catalyst. Employing of tungsten and cobalt revealed a considerable shift in the catalytic performance of g-C3N4. Short reaction time as well as high yield with respect to the reported literatures for formation of amide bond through direct oxidative amidation. W/Co@g-C3N4 could be used in five consecutive runs without any significant drop in activity. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of highly reusable, affordable, and durable photocatalysts for the production of hydrogen peroxide (H 2 O 2) remained a challenge. In this study, a homojunction photocatalyst (SPGCN) is constructed between phosphorylated g-C 3 N 4 (PCN) and sulfur self-doped g-C 3 N 4 (SCN) using a simple wet impregnation method. Later, the obtained SPGCN homojunction is transformed into hydrogel beads using carboxymethyl cellulose via an effective cross-linking strategy (SPGCN/CMC). The photocatalytic beads displayed a phenomenal H 2 O 2 production of 3.5 mM under visible light illumination for 60 min. The SPGCN/CMC hydrogel beads showed a maximum reusability of 10 cycles with a decline of 1.5 mM H 2 O 2 production. The improved photocatalytic efficiency is indicated by strengthened utilization of visible light via tuning of the band gap, suppressed recombination of electron-hole pairs, and higher separation efficiency through the effective construction of Z-scheme between the phosphorylated carbon nitride and the sulfur-self-doped carbon nitride present in the SPGCN/CMC beads. The mechanistic studies affirmed the dominant role of superoxide radicals in H 2 O 2 production. The photocatalytic H 2 O 2 production followed a highly selective two-electron reduction reaction. Overall, this study highlights the efficient engineering of carbon nitride-based materials towards artificial photosynthesis. [ABSTRACT FROM AUTHOR]

Water molecules, which act as both solvent and reactant, play critical roles in photocatalytic reactions for methanol conversion. However, the influence of water on the adsorption of methanol and desorption of liquid products, which are two essential steps that control the performance in photocatalysis, has been well under‐explored. Herein, we reveal the role of water in heterogeneous photocatalytic processes of methanol conversion on the platinized carbon nitride (Pt/C3N4) model photocatalyst. In situ spectroscopy techniques, isotope effects, and computational calculations demonstrate that water shows adverse effects on the adsorption of methanol molecules and desorption processes of methanol oxidation products on the surface of Pt/C3N4, significantly altering the reaction pathways in photocatalytic methanol conversion process. Guided by these discoveries, a photothermal‐assisted photocatalytic system is designed to achieve a high solar‐to‐hydrogen (STH) conversion efficiency of 2.3 %, which is among the highest values reported. This work highlights the important roles of solvents in controlling the adsorption/desorption behaviours of liquid‐phase heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Water molecules, which act as both solvent and reactant, play critical roles in photocatalytic reactions for methanol conversion. However, the influence of water on the adsorption of methanol and desorption of liquid products, which are two essential steps that control the performance in photocatalysis, has been well under‐explored. Herein, we reveal the role of water in heterogeneous photocatalytic processes of methanol conversion on the platinized carbon nitride (Pt/C3N4) model photocatalyst. In situ spectroscopy techniques, isotope effects, and computational calculations demonstrate that water shows adverse effects on the adsorption of methanol molecules and desorption processes of methanol oxidation products on the surface of Pt/C3N4, significantly altering the reaction pathways in photocatalytic methanol conversion process. Guided by these discoveries, a photothermal‐assisted photocatalytic system is designed to achieve a high solar‐to‐hydrogen (STH) conversion efficiency of 2.3 %, which is among the highest values reported. This work highlights the important roles of solvents in controlling the adsorption/desorption behaviours of liquid‐phase heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Dispersible and functionalizable long persistent luminescent (LPL) materials are highly desired for flexible use of LPL in various fields. However, synthesizing metal‐free LPL systems with stable long‐lived intermediates and reactive surface groups, which are key requirements for robust LPL and the ability to be functionalized, has proven to be challenging. Herein, the microwave‐assisted preparation of carbon dots (CDs)‐based LPL materials is demonstrated with abundant surface amino groups via in situ embedding of CDs into carbon nitrides (CNs). The incorporation of CDs leads to the formation of deep traps and promotes exciton transmission between CDs and trap states, contributing to the generation of LPL. By varying the embedded CDs, tunable LPL ranging from blue to yellow can be achieved, with a duration exceeding 10 min. Due to the covalent bonding between CDs and CNs, the materials (named CDs@CNs) exhibit robust LPL under ambient conditions and evenly dispersed in water through ultrasonic treatment. Furthermore, the surface amino groups serve as sites for further modification, allowing for on‐demand performance design and control, such as adjustable hydrophilicity–hydrophobicity for various applications. This work provides new insights into designing superior flexible CDs‐based LPL materials and expanding the domain of metal‐free LPL materials. [ABSTRACT FROM AUTHOR]

• Ag was atomically anchored on ultrathin carbon nitride by thermal polymerization. • Ag doping increased visible-light absorption and decreased the AgUTCN band gap. • Single-atom Ag favored O2 adsorption and subsequent O2•− formation. • O2•− was verified as the major contributor to photocatalysis by AgUTCN. • AgUTCN gives efficient photocatalytic degradation of various PPCPs. Carbon nitride has been extensively used as a visible-light photocatalyst, but it has the disadvantages of a low specific surface area, rapid electron–hole recombination, and relatively low light absorbance. In this study, single-atom Ag was successfully anchored on ultrathin carbon nitride (UTCN) via thermal polymerization, the catalyst obtained is called AgUTCN. The Ag hardly changed the carbon nitride's layered and porous physical structure. AgUTCN exhibited efficient visible-light photocatalytic performances in the degradation of various recalcitrant pollutants, eliminations of 85% were achieved by visible-light irradiation for 1 hr. Doping with Ag improved the photocatalytic performance of UTCN by narrowing the forbidden band gap from 2.49 to 2.36 eV and suppressing electron–hole pair recombination. In addition, Ag doping facilitated O 2 adsorption on UTCN by decreasing the adsorption energy from −0.2 to −2.22 eV and favored the formation of O 2 ·−. Electron spin resonance and radical-quenching experiments showed that O 2 ·− was the major reactive species in the degradation of Acetaminophen (paracetamol, APAP). [Display omitted] [ABSTRACT FROM AUTHOR]

The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation‐decomposition (NID) strategy that is effective in peeling off BCN into few‐layer C3N4 (fl‐CN) with tailored thickness down to bi‐layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl‐CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl‐CN‐530 catalyst is 952 μmol g−1 h−1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on‐site formed H2O2 and active oxygen species to generate value‐added C1 oxygenates with high selectivity of 99.2 % and record‐high production rate of 1893 μmol g−1 h−1 among the metal‐free C3N4‐based photocatalysts. [ABSTRACT FROM AUTHOR]

The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation‐decomposition (NID) strategy that is effective in peeling off BCN into few‐layer C3N4 (fl‐CN) with tailored thickness down to bi‐layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl‐CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl‐CN‐530 catalyst is 952 μmol g−1 h−1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on‐site formed H2O2 and active oxygen species to generate value‐added C1 oxygenates with high selectivity of 99.2 % and record‐high production rate of 1893 μmol g−1 h−1 among the metal‐free C3N4‐based photocatalysts. [ABSTRACT FROM AUTHOR]

Enabling n→π* electronic transition in graphitic carbon nitride (g‐CN) can significantly enhance its photocatalytic performance by extending visible light absorption. However, achieving this transition remains a grand challenge due to the selection rule that restricts it to planar tri‐s‐triazine units of g‐CN. Here, an effective strategy to induce the n→π* transition in g‐CN nanosheets by coupling infrared irradiation with lattice vibrations is presented. Theoretical simulations reveal two prominent vibration modes perpendicular to tri‐s‐triazine units at 219 and 737 cm−1 can promote the corrugation of tri‐s‐triazine units and facilitate the n→π* electronic transition when coupled with infrared irradiation. Additionally, these vibrational modes enable the efficient exfoliation of bulk g‐CN into 2D nanosheets by overcoming the interplanar binding energy. Through femtosecond transient absorption spectra (fs‐TAS), the n→π* transition prolongs the lifetime of photocatalytically active shallow electron trapping states and charge separation states in g‐CN is demonstrated. Accordingly, the activated n→π* electronic transition and prolonged lifetime of photocatalytically active charges lead to an H2 generation rate of 2485 µmol h−1 gcat−1, ≈40 times higher than that of the bulk counterpart. This work highlights the effectiveness of coupling lattice vibrations with infrared irradiation to drive the n→π* transition for enhanced visible‐light photocatalysis. [ABSTRACT FROM AUTHOR]

Carbon nitride (C3N4) has gained considerable attention and has been regarded as an ideal candidate for photocatalytic hydrogen evolution. However, its photocatalytic efficiency is still unsatisfactory due to the rapid recombination rate of photo-generated carriers and restricted surface area with few active sites. Herein, we successfully synthesized a single-atom Pt cocatalyst-loaded photocatalyst by utilizing the anchoring effect of carbon dots (CDs) on C3N4. The introduction of CDs onto the porous C3N4 matrix can greatly enhance the specific surface area of C3N4 to provide more surface-active sites, increase light absorption capabilities, as well as improve the charge separation efficiency. Notably, the functional groups of CDs can efficiently anchor the single-atom Pt, thus improving the atomic utilization efficiency of Pt cocatalysts. A strong interaction is formed via the connection of Pt-N bonds, which enhances the efficiency of photogenerated electron separation. This unique structure remarkably improves its H2 evolution performance under visible light irradiation with a rate of 15.09 mmol h−1 g−1. This work provides a new approach to constructing efficient photocatalysts by using CDs for sustainable hydrogen generation, offering a practical approach to utilizing solar energy for clean fuel production. [ABSTRACT FROM AUTHOR]

The modified carbon nitride nanozyme could realize biomimetic catalysis application for evaluation of total antioxidant capacity via self-cascade photocatalytic H 2 O 2 production. [Display omitted] The peroxidase mimics usually requires the addition of exogenous hydrogen peroxide (H 2 O 2), which greatly hinder their practical applications. Herein, through rational co-modification of multiple elements (potassium (K), chlorine (Cl) and iodine (I)), the modified carbon nitride nanomaterials (KCl/KI-CN) could serve as efficient bifunctional catalysts. The multiple elements doping and the incorporation of cyano groups (C N) are deemed to enhance their photocatalytic and peroxidase-like activity, respectively. Based on the photocatalytic function, H 2 O 2 can be produced continuously and steadily via two-electron oxygen reduction over modified carbon nitride under visible light irradiation. Subsequently, the KCl/KI-CN could catalyze the chromogenic substrate by the in-situ produced H 2 O 2. Taking advantage of the bifunctional properties of modified carbon nitride, we for the first time demonstrate a self-cascade catalytic process and apply successfully for the ascorbic acid (AA) detection and versatile total antioxidant capacity (TAC) evaluation. This paper not only prepares an efficiently bifunctional catalyst but also provides a new self-cascade photocatalytic H 2 O 2 production strategy for the peroxidase-like application. [ABSTRACT FROM AUTHOR]