Templateless Infrared Heating Process for Fabricating Carbon Nitride Nanorods with Efficient Photocatalytic H2 Evolution

Boosting the Efficiency of Photoactive Rod-Shaped Nanomotors via Magnetic Field-Induced Charge Separation

Photocatalytic nanomotors have attracted a lot of attention because of their unique capacity to simultaneously convert light and chemical energy into mechanical motion with a fast photoresponse. Recent discoveries demonstrate that the integration of optical and magnetic components within a single nanomotor platform offers novel advantages for precise motion control and enhanced photocatalytic performance. Despite these advancements, the impact of magnetic fields on energy transfer dynamics in photocatalytic nanomotors remains unexplored. Here, we introduce dual-responsive rod-like nanomotors, made of a TiO2/NiFe heterojunction, able to (i) self-propel upon irradiation, (ii) align with the direction of an external magnetic field, and (iii) exhibit enhanced photocatalytic performance. Consequently, when combining light irradiation with a homogeneous magnetic field, these nanomotors exhibit increased velocities attributed to their improved photoactivity. As a proof-of-concept, we investigated the ability of these nanomotors to generate phenol, a valuable chemical feedstock, from benzene under combined optical and magnetic fields. Remarkably, the application of an external magnetic field led to a 100% increase in the photocatalytic phenol generation in comparison with light activation alone. By using various state-of-the-art techniques such as photoelectrochemistry, electrochemical impedance spectroscopy, photoluminescence, and electron paramagnetic resonance, we characterized the charge transfer between the semiconductor and the alloy component, revealing that the magnetic field significantly improved charge pair separation and enhanced hydroxyl radical generation. Consequently, our work provides valuable insights into the role of magnetic fields in the mechanisms of light-driven photocatalytic nanomotors for designing more effective light-driven nanodevices for selective oxidations.

Enhancing photocatalytic overall water-splitting performance on dual-active-sites of the Co-P@MoS2 catalysts: a DFT study

The rational construction of photocatalysts possesses tremendous potential to solve the energy crisis and environmental pollution; however, designing a catalyst for solar-driven overall water-splitting remains a great challenge. Herein, we propose a new MoS2-based photocatalyst (Co-P@MoS2), which skillfully uses the cobalt (Co) atom to stimulate in-plane S atoms and employs the phosphorus (P) atom to stabilize the basal plane by forming the Co-P bands. Using density functional theory (DFT), it was found that oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) can occur at the P site and S2 site of the Co-P@MoS2, respectively, and the dual-active sites successfully makes a delicate balance between the adsorption and dissociation of hydrogen. Furthermore, the improved overall water-splitting performance of Co-P@MoS2 was verified by analyzing the results of the electron structure and the dynamics of photogenerated carries. It was found that the imbalance of electron transfer caused by the introduction of the Co atom was the main contributor to the catalytic activity of Co-P@MoS2. Our study broadens the idea of developing photocatalysts for the overall water-splitting.

Graphitic carbon nitride (g-C3N4)-based photocatalytic materials for hydrogen evolution

The semiconductors, such as TiO₂, CdS, ZnO, BiVO₄, graphene, produce good applications in photocatalytic water splitting for hydrogen production, and great progress have been made in the synthesis and modification of the materials. As a two-dimensional layered structure material, graphitic carbon nitride (g-C₃N₄), with the unique properties of high thermostability and chemical inertness, excellent semiconductive ability, affords good potential in photocatalytic hydrogen evolution. However, the related low efficiency of g-C₃N₄ with fast recombination rate of photogenerated charge carriers, limited visible-light absorption, and low surface area of prepared bulk g-C₃N₄, has called out the challenge issues to synthesize and modify novel g-C₃N₄-block photocatalyst. In this review, we have summarized several strategies to improve the photocatalytic performance of pristine g-C₃N₄ such as pH, morphology control, doping with metal or non-metal elements, metal deposition, constructing a heterojunction or homojunction, dye-sensitization, and so forth. The performances for photocatalytic hydrogen evolution and possible development of g-C₃N₄ materials are shared with the researchers interested in the relevant fields hereinto.

Hierarchical Porous Carbon Nitride-Crumpled Nanosheet-Embedded Copper Single Atoms: An Efficient Catalyst for Carbon Monoxide Oxidation

Rational design of metal single-site embedded porous graphitic carbon nitride (P-g-C₃N₄) nanostructures exploiting maximum atom utilization is warranted to enhance the thermal CO oxidation (CO_Ox) reaction. Herein, a facile, green, one-pot, and template-free approach is developed to fabricate the hierarchical porous P-g-C₃N₄-crumpled ultrathin nanosheets atomically doped with copper single atoms (Cu-P-g-C₃N₄). Mechanistically, the quick protonation of melamine and pyridine under acidic conditions induces deamination to form melem, which is polycondensed under heating. The interconnected pores, high surface area (240 m²g^-1), and maximized exposed isolated Cu atomic active sites (1.8 wt %) coordinated with nitrogen atom P-g-C₃N₄ are the salient features of Cu- P-g-C₃N₄ that endowed complete conversion to CO₂ at 184 °C. In contrast, P-g-C₃N₄ only converted 3.8% of CO even at 350 °C, implying the electronic effect of Cu single atoms. The abundant Cu-nitrogen moieties can drastically weaken the binding affinity of the CO-oxidation (CO_Ox) intermediates and products, thus accelerating the reaction kinetics at a low temperature. This study may promote the fabrication of P-g-C₃N₄ doped with various single atoms for the oxidation of CO.

Graphene-based nanocomposites and nanohybrids for the abatement of agro-industrial pollutants in aqueous environments

Incessant release of a large spectrum of agro-industrial pollutants into environmental matrices remains a serious concern due to their potential health risks to humans and aquatic animals. Existing remediation techniques are unable to remove these pollutants, necessitating the development of novel treatment approaches. Due to its unique structure, physicochemical properties, and broad application potential, graphene has attracted a lot of attention as a new type of two-dimensional nanostructure. Given its chemical stability, large surface area, electron mobility, superior thermal conductivity, and two-dimensional structure, tremendous research has been conducted on graphene and its derived composites for environmental remediation and pollution mitigation. Various methods for graphene functionalization have facilitated the development of different graphene derivatives such as graphene oxide (GO), functional reduced graphene oxide (frGO), and reduced graphene oxide (rGO) with novel attributes for multiple applications. This review provides a comprehensive read on the recent progress of multifunctional graphene-based nanocomposites and nanohybrids as a promising way of removing emerging contaminants from aqueous environments. First, a succinct overview of the fundamental structure, fabrication techniques, and features of graphene-based composites is presented. Following that, graphene and GO functionalization, i.e., covalent bonding, non-covalent, and elemental doping, are discussed. Finally, the environmental potentials of a plethora of graphene-based hybrid nanocomposites for the abatement of organic and inorganic contaminants are thoroughly covered.

Promoting Spatial Charge Transfer of ZrO2 Nanoparticles: Embedded on Layered MoS2/g-C3N4 Nanocomposites for Visible-Light-Induced Photocatalytic Removal of Tetracycline

Photocatalytic degradation is a sustainable technique for reducing the environmental hazards created by the overuse of antibiotics in the food and pharmaceutical industries. Herein, a layer of MoS₂/g-C₃N₄ nanocomposite is introduced to zirconium oxide (ZrO₂) nanoparticles to form a "particle-embedded-layered" structure. Thus, a narrow band gap (2.8 eV) starts developing, deliberated as a core photodegradation component. Under optimization, a high photocatalytic activity of 20 mg/L TC at pH 3 with ZrO₂@MoS₂/g-C₃N₄ nanocomposite was achieved with 94.8% photocatalytic degradation in 90 min. A photocatalytic degradation rate constant of 0.0230 min^-1 is determined, which is 2.3 times greater than the rate constant for bare ZrO₂ NPs. The superior photocatalytic activity of ZrO₂@MoS₂/g-C₃N₄ is due to the dual charge-transfer channel between the MoS₂/g-C₃N₄ and ZrO₂ nanoparticles, which promotes the formation of photogenerated e^-/h⁺ pairs. Charge recombination produces many free electron-hole pairs, which aid photocatalyst reactions by producing superoxide and hydroxyl radicals via electron-hole pair generation. The possible mechanistic routes for TC were investigated in-depth, as pointed out by the liquid chromatography-mass spectrometry (LC-MS) investigation. Overall, this work shows that photocatalysis is a feasible sorbent approach for environmental antibiotic wastewater treatment.

In Situ Growth of ZnIn2S4 on MOF-Derived Ni-Fe LDH to Construct Ternary-Shelled Nanotubes for Efficient Photocatalytic Hydrogen Evolution

A rational design of a novel ternary-shelled nanotube is attractive in photocatalytic water splitting. Herein, ZnIn₂S₄ nanosheets were in situ grown on the surface of MIL-88A-derived Ni-Fe layered double hydroxide (LDH) to fabricate ternary-shelled nanotubes (ZIS@Ni-Fe LDH) via a self-assembly strategy. Characterization indicates that the ZIS@Ni-Fe LDH heterostructure exhibits a high surface area and a well-defined ternary-shelled hollow structure. The optimal heterostructure presents a remarkably improved photocatalytic hydrogen production rate (2035.81 μmol g^-1 h^-1) compared with bare ZnIn₂S₄ and MIL-88A-derived Ni-Fe LDH under visible light illumination. The effect of ZnIn₂S₄ loading on the photocatalytic performance and stability of ZIS@Ni-Fe LDH is systematically studied. The ZIS@Ni-Fe LDH heterostructure can make better use of the inner space, provide abundant reactive sites, improve light harvesting, accelerate interfacial electron transfer, and further promote photocatalytic hydrogen evolution. Based on the electrocatalytic performance, the probable photocatalytic mechanism and the electron transfer pathway can be proposed. Our work provides a facile and efficient strategy to construct ternary-shelled heterojunction photocatalysts.

Vanadium-doped graphitic carbon nitride for multifunctional applications: Photoelectrochemical water splitting and antibacterial activities

Bulk graphitic carbon nitride (g-C3N4) exhibits limited water splitting efficiency due todrawbacks including high charge recombination rate, low electrical conductivity, poor quantum efficiency, and few adsorption and active catalytic sites. Herein, we report V-doped g-C3N4 nanoarchitectures prepared via direct calcination of urea and ammonium metavanadate. The obtained V-doped g-C3N4 nanostructures not only improved the visible light absorption property but also increased the charge separation and transportation, resulting in extremely enhanced water splitting activity. The structural, morphological, and optical analysis results confirmed the successful incorporation of V into the host g-C3N4 material, and electrochemical impedance spectroscopy measurements revealed the charge carrier dynamics. Compared to the pristine g-C3N4 photoelectrode, the optimized 0.3 mol% V-doped g-C3N4 photoelectrode showed a considerably higher photocurrent density (0.80 mA cm-2). The enhancement of the catalytic performance could be attributed to the synergistic effects of prolonged light absorption, improved transfer of electrons and holes, and extra active catalytic sites for water splitting. Further, the optimized 0.3 mol% V-doped g-C3N4 sample showed an antibacterial activity higher than that of the undoped photocatalyst.

g-C3N4 Modified by meso-Tetrahydroxyphenylchlorin for Photocatalytic Hydrogen Evolution Under Visible/Near-Infrared Light

A new photocatalyst denoted as mTHPC/pCN was prepared by modifying protonated graphitic carbon nitride (pCN) by meso-tetrahydroxyphenylchlorin (mTHPC). Relevant samples were characterized via various methods including zeta potential measurements, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N₂ adsorption–desorption, transmission electron microscopy, ultraviolet-visible–near-infrared spectroscopy, electrochemical impedance spectroscopy, photocurrent response measurements, electron spin resonance spectroscopy, and phosphorescence spectroscopy. Compared with pCN, mTHPC/pCN shows enhanced absorption in the visible and near-infrared regions and thus higher photocatalytic activity in hydrogen evolution. A possible mechanism for mTHPC/pCN is proposed.

Co3O4 Nanocrystals with an Oxygen Vacancy-Rich and Highly Reactive (222) Facet on Carbon Nitride Scaffolds for Efficient Photocatalytic Oxygen Evolution

Oxygen evolution reaction (OER) with sluggish kinetics is the rate-determining step of water splitting, which dominates the solar-to-hydrogen fuel conversion efficiency. Herein, we constructed an oxygen vacancy-rich and highly reactive (222) facet in Co₃O₄ nanocrystals anchored on carbon nitride nanofiber (CNF) by a solvothermal reduction method. The resulting Co₃O₄ nanocrystals/CNF (COCNF) demonstrated a dramatically enhanced OER with a rate of 24.9 μmol/h under visible light, which is 124 times higher than that of CNF. This excellent catalytic activity of COCNF is based on a synergistic effect between its binary components for charge separation, oxygen vacancies for enhanced conductivity, and facet (222) exposure of Co₃O₄ nanocrystals for improved heterogeneous kinetics. Density functional theory (DFT) calculations revealed the water oxidation mechanism at different facets and found that the formed oxygen vacancies lead to a reduction of the materials' bandgap. The correlation between Co₃O₄ crystal facets and the inherent OER catalytic activities under acidic solution was in the order of (222) > (220) > (311).

A curly architectured graphitic carbon nitride (g-C3N4) towards efficient visible-light photocatalytic H2 evolution

The unique curly-like architecture g-C₃N₄ with excellent photocatalytic H₂ evolved activity was reported by a facile precursor-reforming strategy.

Progress in the functional modification of graphene/graphene oxide: a review

Graphene and graphene oxide have attracted tremendous interest over the past decade due to their unique and excellent electronic, optical, mechanical, and chemical properties. This review focuses on the functional modification of graphene and graphene oxide. First, the basic structure, preparation methods and properties of graphene and graphene oxide are briefly described. Subsequently, the methods for the reduction of graphene oxide are introduced. Next, the functionalization of graphene and graphene oxide is mainly divided into covalent binding modification, non-covalent binding modification and elemental doping. Then, the properties and application prospects of the modified products are summarized. Finally, the current challenges and future research directions are presented in terms of surface functional modification for graphene and graphene oxide.

Graphene and graphene oxide have attracted tremendous interest over the past decade due to their unique and excellent electronic, optical, mechanical, and chemical properties.

Ce-Doped Graphitic Carbon Nitride Derived from Metal Organic Frameworks as a Visible Light-Responsive Photocatalyst for H2 Production

Novel fibrous graphitic carbon nitride (g-C₃N₄) derivatives prepared from metal organic frameworks (MOFs) were doped with Ce³⁺ (Ce-C₃N₄) as photocatalytic materials. Ce-C₃N₄ was characterized using various techniques, revealing its high specific surface area, excellent photocatalytic activity, and stability for H₂ evolution under visible light irradiation. The fluorine modified samples show superior photocatalytic activity under visible light irradiation, which is due to the presence of more active sites and enhanced absorption of solar energy. This work provides a new synthetic route for MOF-derived g-C₃N₄ that can be doped with different metal ions. The fluorine modified Ce-C₃N₄ is an efficient photocatalyst with potential for many applications related to energy and the environment.

One-pot fabrication of Fe-doped carbon nitride nanoparticles as peroxidase mimetics for H2O2 and glucose detection

Iron-doped carbon nitride nanoparticles (Fe-CNNPs) were prepared from citric acid, urea and ferric chloride through a convenient one-pot solvothermal method. Oleic acid was used as the reaction medium. The morphology and chemical composition of the obtained Fe-CNNPs were characterized by multiple methods including transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). It is interesting to find that the Fe-CNNPs showed higher catalytic activity than horseradish peroxidase (HRP), and tetramethylbenzidine (TMB) can be catalytically oxidized in the presence of H₂O₂ to produce a color change in aqueous solution. As H₂O₂ can be generated in the oxidation process of glucose catalyzed by glucose oxidase (GOD), a novel sensitive method for the detection of glucose with a limit of detection (LOD) of 0.29 μM has been developed combined with the catalytic properties of GOD and Fe-CNNPs. The Fe-CNNPs with peroxidase mimetics activity may have potential applications in biotechnology field.

Facet-Dependent Interfacial Charge Transfer in TiO2/Nitrogen-Doped Graphene Quantum Dots Heterojunctions for Visible-Light Driven Photocatalysis

Interfacial charge transfer is crucial in the efficient conversion of solar energy into fuels and electricity. In this paper, heterojunction composites were fabricated, comprised of anatase TiO2 with different percentages of exposed {101} and {001} facets and nitrogen-doped quantum dots (NGQDs) to enhance the transfer efficiency of photo-excited charge carriers. The photocatalytic performances of all samples were evaluated for RhB degradation under visible light irradiation, and the hybrid containing TiO2 with 56% {001} facets demonstrated the best photocatalytic activity. The excellent photoactivity of TiO2/NGQDs was owed to the synergistic effects of the following factors: (i) The unique chemical features of NGQDs endowed NGQDs with high electronic conductivities and provided its direct contact with the TiO2 surface via forming Ti–O–C chemical bonds. (ii) The co-exposed {101} and {001} facets were beneficial for the separation and transfer of charge carriers in anatase TiO2. (iii) The donor-acceptor interaction between NGQDs and electron-rich {101} facets of TiO2 could remarkably enhance the photocurrent, thus hindering the charge carriers recombination rate. Extensive characterization of their physiochemical properties further showed the synergistic effect of facet-manipulated electron-hole separation in TiO2 and donor-acceptor interaction in graphene quantum dots (GQDs)/TiO2 on photocatalytic activity.

Template-free synthesis of salmon pink tube-shaped structure carbon nitride with enhanced visible light photocatalytic activity

Designing a highly active and stable photocatalyst to directly solve environmental pollution is desirable for solar energy conversion. Herein, an effective strategy, hydrothermal-calcination, for synthesizing extremely active carbon nitride (salmon pink) from a low-cost precursor melamine, is reported. The salmon pink carbon nitride with tube-shaped structure significantly enhanced response to visible light, improved efficiency of charge separation and remarkably enhanced efficiency of methyl orange (MO) degradation than bulk g-C₃N₄ (light orange). The M-10-200-24-600 composite possessed the most wonderful ability towards MO degradation irradiated by visible light, which could achieve a highest degradation efficiency of 84% within 120 min. Our findings may provide a promising and facile approach to highly efficient photocatalysis for solar-energy conversion.

Designing a highly active and stable photocatalyst to directly solve environmental pollution is desirable for solar energy conversion.

Versatile Synthesis of Pd and Cu Co-Doped Porous Carbon Nitride Nanowires for Catalytic CO Oxidation Reaction

Developing efficient catalyst for CO oxidation at low-temperature is crucial in various industrial and environmental remediation applications. Herein, we present a versatile approach for controlled synthesis of carbon nitride nanowires (CN NWs) doped with palladium and copper (Pd/Cu/CN NWs) for CO oxidation reactions. This is based on the polymerization of melamine by nitric acid in the presence of metal-precursors followed by annealing under nitrogen. This intriguingly drove the formation of well-defined, one-dimensional nanowires architecture with a high surface area (120 m2 g−1) and doped atomically with Pd and Cu. The newly-designed Pd/Cu/CN NWs fully converted CO to CO2 at 149 °C, that was substantially more active than that of Pd/CN NWs (283 °C) and Cu/CN NWs (329 °C). Moreover, Pd/Cu/CN NWs fully reserved their initial CO oxidation activity after 20 h. This is mainly attributed to the combination between the unique catalytic properties of Pd/Cu and outstanding physicochemical properties of CN NWs, which tune the adsorption energies of CO reactant and reaction product during the CO oxidation reaction. The as-developed method may open new frontiers on using CN NWs supported various noble metals for CO oxidation reaction.

One-Step Nickel Foam Assisted Synthesis of Holey G-Carbon Nitride Nanosheets for Efficient Visible-Light Photocatalytic H2 Evolution

Graphitic carbon nitride (g-C₃N₄) with layered structure represents one of the most promising metal-free photocatalysts. As yet, the direct one-step synthesis of ultrathin g-C₃N₄ nanosheets remains a challenge. Here, few-layered holey g-C₃N₄ nanosheets (CNS) were fabricated by simply introducing a piece of nickel foam over the precursors during the heating process. The as-prepared CNS with unique structural advantages exhibited superior photocatalytic water splitting activity (1871.09 μmol h^-1 g^-1) than bulk g-C₃N₄ (BCN) under visible light (λ > 420 nm) (≈31 fold). Its outstanding photocatalytic performance originated from the high specific surface area (240.34 m² g^-1) and mesoporous structure, which endows CNS with more active sites, efficient exciton dissociation, and prolonged charge carrier lifetime. Moreover, the obvious upshift of the conduction band leads to a larger thermodynamic driving force for photocatalytic proton reduction. This methodology not only had the advantages for the direct and green synthesis of g-C₃N₄ nanosheets but also paved a new avenue to modify molecular structure and textural of g-C₃N₄ for advanced applications.

Unprecedented Centimeter-Long Carbon Nitride Needles: Synthesis, Characterization and Applications

Free standing centimeter-long 1D nanostructures are highly attractive for electronic and optoelectronic devices due to their unique photophysical and electrical properties. Here a simple, large-scale synthesis of centimeter-long 1D carbon nitride (CN) needles with tunable photophysical, electric, and catalytic properties is reported. Successful growth of ultralong needles is acquired by the utilization of 1D organic crystal precursors comprised of CN monomers as reactants. Upon calcination at high temperatures, the shape of the starting crystal is fully preserved while the CN composition and porosity, and optical and electrical properties can be easily tuned by tailoring the starting elements ratio and final calcination temperature. The facile manipulation and visualization of the CN needles endow their direct electrical measurements by placing them between two conductive probes. Moreover, the CN needles exhibit good photocatalytic activity for hydrogen production owing to their improved light harvesting properties, high surface area, and advantageous energy bands position. The new growth strategy developed here may open opportunities for a rational design of CN and other metal-free materials with controllable directionality and tunable photophysical and electronic properties, toward their utilization in (photo)electronic devices.

Enhanced Photocatalytic Hydrogen Evolution of NiCoP/g-C3 N4 with Improved Separation Efficiency and Charge Transfer Efficiency

Although NiCoP has attracted much attention in the field of electrocatalysis, the study of its photocatalytic activity and mechanism have been somewhat limited. NiCoP/g-C₃ N₄ , synthesized by simple one-pot method, is a highly efficient photocatalyst for hydrogen production from water. NiCoP/g-C₃ N₄ exhibits a hydrogen evolution rate of 1643 μmol h^-1  g^-1 , which is 21 times higher than that of bare g-C₃ N₄ . The excellent performance is due to a combination of improved separation efficiency and effective charge transfer efficiency. The photogenerated charge behavior is characterized by the surface photovoltage (SPV), transient photovoltage (TPV), and photoluminescence spectroscopy. The photogenerated charge transport is investigated by electrochemical impedance spectroscopy and polarization curve. Moreover, the effective charge transfer efficiency was measured according to the mimetic apparent quantum yield. SPV and TPV measurements, whereby 10 vol % of a triethanolamine-water mixture was added into the testing system, were taken to simulate the real atmosphere for photocatalytic reaction, which can give rise to the photogenerated charge transfer process. A possible photocatalytic mechanism was also proposed. This study may provide an efficient theoretical basis to design transition metal phosphide cocatalyst-modified photocatalysts.

Exploitation of the synergistic effect between surface and bulk defects in ultra-small N-doped titanium suboxides for enhancing photocatalytic hydrogen evolution

The work utilizes the “double-faced” roles of surface and bulk defects in engineering photocatalytic activity.

Fabrication of carbon nanotube-multiporphyrin array composites as light-sensitizer for photocurrent generation, photochromism of viologen and catalytic degradation of methyl orange

Multiporphyrin arrays were assembled on the surface of MWNTs to produce light-sensitive nano-composites with improved opto-electric conversion efficiency, photochromic, and photocatalytic performance.

Enhancing Photocatalytic Activity of Graphitic Carbon Nitride by Codoping with P and C for Efficient Hydrogen Generation

The generation of clean hydrogen gas from photocatalytic water splitting by using graphitic carbon nitride (g-C₃N₄) as the photocatalyst has attracted considerable research interest. For practical applications, however, the photocatalytic activity of g-C₃N₄ needs to be further improved by, for example, band gap engineering through heteroatom doping. In this study, we found that doping of carbon nitride with carbon and phosphorus (P) could tune energy level of the conduction band. Subsequent hydrothermal treatment led to an increase in the specific surface area from 24.9 up to 141.1 m² g^-1, which was accompanied by increasing C concentration of the resultant C, P-doped g-C₃N₄ to reduce the hole-electron recombination and enhance the conductivity. Consequently, the C, P-codoped g-C₃N₄ (i.e., CPCN-1*) exhibited a much enhanced photocatalytic activity for efficient generation of H₂ by photocatalytic water splitting under visible-light irradiation (1493.3 μmol g^-1 h^-1-about 9.7 times enhancement from that of bulk g-C₃N₄).

A quasi-hexagonal prism-shaped carbon nitride for photoreduction of carbon dioxide under visible light

A quasi-hexagonal prism-shaped carbon nitride (H-C₃N₄) was synthesized from urea-derived C₃N₄ (U-C₃N₄) using an alkaline hydrothermal process. U-C₃N₄ decomposition followed by hydrogen bond rearrangement of hydrolyzed products leads to the formation of a quasi-hexagonal prism-shaped structure. The H-C₃N₄ catalysts displayed superior activity in the photoreduction of CO₂ with H₂O compared to U-C₃N₄. The enhanced photocatalytic activities can be attributed to the promotion of incompletely coordinated nitrogen atom formation in the C₃N₄ molecules. Graphical abstract ᅟ.

New complete assignment of X-ray powder diffraction patterns in graphitic carbon nitride using discrete Fourier transform and direct experimental evidence

To date, there have been only a few studies focusing on the assignment of X-ray diffraction (XRD) patterns in graphitic carbon nitrides (g-C₃N₄) and contradictory determination for a broad peak around 12°–14° has been perplexing.

Improved Photocatalytic H2 Evolution over G-Carbon Nitride with Enhanced In-Plane Ordering

A series of rod-like porous graphitic-carbon nitrides (short as CNs) with enhanced in-plane ordering have been fabricated through self-assembled heptazine hydrate precursors for the first time. By controlling the calcination of the preformed precursors with different temperature-rising rates, the resulted CNs (SAHEP-CNs-1) with the most ordered and least stacked graphitic planar are showing a tremendously improved hydrogen evolution rate of 420 μmol h^-1 under visible light and a remarkable apparent quantum efficiency of 8.9% at 420 nm, which is among the highest values for C₃ N₄ -related photocatalysts in the literature. This work discloses that enhancing in-plane ordering is one critical factor for improving the photocatalytic H₂ evolution of carbon nitride, which is an effective solution to prolong the lifetime of charge carriers by accelerating the charge transport and separation within the graphitic planar. This finding would present a facial strategy for the designing of efficient organic semiconductors for photocatalysis.