Pure Nitride Research Articles

Photocatalysis and adsorption coupling in S-scheme K and P doped g-C3N4/GO/MgFe2O4 photocatalyst for enhanced degradation of Congo red dye

Abstract Photocatalysis is an environmentally friendly approach for harnessing solar light to degrade pollutants. This study investigates the degradation of Congo red (COR) dye by a visible light-active photocatalyst, with a primary focus on the efficiency and reusability of the photocatalytic material. We synthesized phosphorus- and potassium-doped graphitic carbon nitride photocatalysts attached to graphene oxide and MgFe2O4 (KPCN/GO/MgFe2O4). Doping graphitic carbon nitride enhanced light absorption, while graphene oxide improved the adsorption properties. The addition of magnetic MgFe2O4 enhanced charge separation and reusability. The KPCN/GO/MgFe2O4 composite was analyzed using a range of techniques. The activity of the synthesized materials for Congo red (COR) dye degradation was analyzed under visible light. The photocatalytic activities of bare, binary, and ternary photocatalysts were compared, and KPCN/GO/MgFe2O4 exhibited the highest photoactivity among all. The KPCN/GO/MgFe2O4 photocatalyst (60 mg) showed a 76% removal efficiency for 5 x 10-6 M Congo red within 60 minutes, which was 2.5 times higher than that of pure graphitic carbon nitride. The •OH and •O2- were the major reactive species during COR photodegradation. The photocatalyst also displayed good reusability after five cycles, enhancing its overall effectiveness.

Sensitivity of pure and Ni-decorated boron nitride B12N12 nanocages toward CH4, H2S, and N2 biogases: A DFT study

The sensitivity of pure and Ni-decorated boron nitride (B12N12) nanocages toward CH4, H2S, and N2 biogases was adequately unveiled by employing versatile density functional theory (DFT) calculations. In this regard, the Gas∙∙∙B12N12 and ∙∙∙Ni@B12N12 complexes were studied within all possible configurations. Based on the energetic quantities, the Ni@B12N12 nanocage exhibited higher sensitivity than the pure one toward the investigated gases. Among all studied complexes, the H2S∙∙∙Ni@B12N12 complex exhibited the most favorable adsorption (Eads) and interaction (Eint) energies with values of –29.25 and –29.46 kcal/mol, respectively. According to the outlines of the quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) index analyses, the closed-shell nature of the interactions within the investigated complexes was ensured. Substantial alterations in the molecular orbitals distribution patterns of pure and Ni-decorated B12N12 nanocages were observed, announcing the occurrence of the adsorption process within the investigated complexes. The obtained negative values of thermodynamic parameters ensured the spontaneous exothermic nature of the investigated Ni-decorated complexes. Upon density of states (DOS) analysis, the influence of adsorbed gases on the electronic characteristics of the pure and Ni-decorated B12N12 nanocages was highlighted. According to the emerging findings, the pure and Ni-decorated B12N12 nanocages are promising sensing materials for biogas components, especially CH4, H2S, and N2 gases.

Boosted photothermal-assisted photocatalytic H2 production by dual heat source-based S-scheme heterojunction

With advances in catalytic research, improvement of catalytic efficiency by using photothermal synergies to strengthen the reaction mechanisms has been focused. In this work, a novel photothermal-assisted photocatalytic H2 production system was constructed by loading Co3O4 nanoparticles on surface of black carbon nitride (BCN) nanosheets, served as the dual thermal source to enhance photothermal effect for synergistically assisting in photocatalytic H2 evolution with optimal H2 production rate reached 3.7 mmol g−1 h−1, significantly higher than that of pure carbon nitride (CN) and BCN. Moreover, the S-scheme heterojunction is also formed between Co3O4 and BCN, leading to the optimization of the charge transfer path, which further promotes the improvement of photothermal-assisted photocatalytic H2 production activity. This study provides the design idea of coupling the multi-heat source effect with the heterojunction electron transport for constructing an efficient photothermal-assisted hydrogen production system.

Deep subwavelength topological edge state in a hyperbolic medium.

Topological photonics offers the opportunity to control light propagation in a way that is robust from fabrication disorders and imperfections. However, experimental demonstrations have remained on the order of the vacuum wavelength. Theoretical proposals have shown topological edge states that can propagate robustly while embracing deep subwavelength confinement that defies diffraction limits. Here we show the experimental proof of these deep subwavelength topological edge states by implementing periodic modulation of hyperbolic phonon polaritons within a van der Waals heterostructure composed of isotopically pure hexagonal boron nitride flakes on patterned gold films. The topological edge state is confined in a subdiffraction volume of 0.021 µm3, which is four orders of magnitude smaller than the free-space excitation wavelength volume used to probe the system, while maintaining the resonance quality factor above 100. This finding can be directly extended to and hybridized with other van der Waals materials to broadened operational frequency ranges, streamline integration of diverse polaritonic materials, and compatibility with electronic and excitonic systems.

Ultrathin-N2C-Deficient Carbon Nitride for Stabilized Enhancement of Electrochemiluminescence.

In the realm of electrochemiluminescence (ECL), the issue of weak signal intensity and instability linked with pure graphitic carbon nitride (CN) is widely recognized. This study suggests a method to produce nitrogen-deficient (N2C) porous ultrathin CN (UACN) using ammonium acetate and ultrasonication. The ultrathin porous nature of UACN provides numerous N2C defects as catalytic sites, aiding in the decomposition of K2S2O8, a conclusion supported by density functional theory (DFT). Importantly, N2C defects serve as electron traps, assisting in electron localization and enhancing the recombination of electron-hole pairs, thereby achieving stable and intensified luminescence from UACN. In practical use, UACN, acting as an ECL emitter, is utilized in detecting the tumor marker carcinoembryonic antigen (CEA), effectively establishing a highly sensitive immunosensing platform. This study elucidates the correlation between UACN structure and ECL performance, offering crucial insights for comprehending ECL mechanisms and designing high-performance ECL materials.

Ag2Se nanoparticles anchored on S-g-C3N4 nanosheets towards efficient photocatalytic tetracycline hydrochloride removal and H2 generation

To improve the stability of Ag based co-catalysts and to increase the photocatalytic performance of graphitic carbon nitride (g-C3N4), Ag2Se nanoparticles were grown onto superior thin sulfur-doped g-C3N4 nanosheets which was fabricated via two-step thermal polymerization at high temperature. Ultrathin S-doped g-C3N4 nanosheets were prepared via two-step thermal polymerization using melamine and thiourea. The ratios of Ag2Se were adjusted to fabricate a series of Ag2Se/S-g-C3N4 (Ag2Se/SCN) composite samples by controlled solvothermal synthesis. S-doping plays an important role in mono-dispersion of Ag2Se nanoparticles on S-g-C3N4 nanosheets because of the control of growth sites. The photocatalytic removal of tetracycline hydrochloride test indicates that sample Ag2Se/SCN-3 with Ag2Se loading of 3 % reveals the best removal effect, in which tetracycline hydrochloride of 60 % is removed within 60 min. Photocatalytic hydrogen generation test results without co-catalyst addition demonstrate that sample Ag2Se/SCN-3 exhibits the best H2 evolution rate of 2116.35 μmol·g−1·h−1, which is 3.8 times of that of pure carbon nitride. The photocatalytic mechanism tests suggest that Schottky heterojunctions are formed in the Ag2Se/S-g-C3N4 composites. The formation of Schottky heterojunctions improved the separation efficiency of photogenerated charge carriers. The incorporation of Ag2Se nanoparticles (as the co-catalyst) on S-g-C3N4 nanosheets is the key for drastically improving the photocatalytic performance and eliminating the use of Pt co-catalyst during the photocatalytic processes.

In Situ Growth of CdS Nanoparticles Between g‐C3N4 Layers for Photocatalytic Reduction of Nitrobenzene

AbstractPhotocatalysis 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.

Defective Carbon Nitride with Dual-surface Engineering for Highly Efficient Photocatalytic Hydrogen Evolution under Visible Light Irradiation.

Defective carbon nitride (DCN-x) was synthesized through a dual-surface engineering process consisting of nitric acid treatment followed by high-temperature calcination. This process endowed DCN-x with a porous structure and a larger surface area than that of pure graphite carbon nitride (CN), enhancing its visible light absorption and reducing the electron-hole recombination rate. Consequently, DCN-x demonstrated a significantly more efficient photocatalytic hydrogen evolution, with the optimum sample, DCN-600, achieving an activity 55.9 times greater than that of pure CN, while maintaining excellent photocatalytic stability. Furthermore, the presence of tri-s-triazine (heptazine) structures within the CN's in-plane structure was identified as a critical factor for band gap optimization, suggesting new avenues for the synthesis of carbon nitride variants with enhanced photocatalytic performance.

Thermally Controlled Synthesis of Cr2(NCN)3/CrN Heterostructured Composite Anodes for High‐Performance Li‐Ion Batteries

AbstractCr2(NCN)3 features high specific capacity and fast electrical conductivity, making it a promising anode candidate for Li‐ion batteries. However, inherent chemical and structural metastability severely restrict its capacity output and cycle life, resulting in unsatisfactory battery performance. Here we use its thermal instability characteristic and propose a thermal controlled structural coordination strategy to in‐situ construct a Cr2(NCN)3/CrN heterostructure. Systematic studies reveal the thermodynamic structural evolution of Cr2(NCN)3 under precise temperature regulation, as well as the essential relevancy between electrochemical properties and crystalline structures. An optimal Cr2(NCN)3/CrN heterostructural composite obtained at 690 °C features uniform two‐phase recombination with abundant grain boundaries enables promising electrochemical performance, exhibiting a high reversible discharge capacity (760 mAh g−1) and a good cycle performance (75 % retention after 100 cycles). It is worth noting that the above performance is significantly improved over unmodified pure transition metal carbodiimides or metal nitride anodes. This study provides a simple and universal structural regulation strategy for transition metal carbodiimides that utilizes their thermal sensitivity to synchronously construct synergistic transition metal carbodiimides/transition metal nitrides heterostructures, promoting their potential applications in Li‐ion batteries.

Single‐Source Precursor Synthesis of a Compositionally Complex Early Transitional Metal Carbonitride (Ti,Zr,Hf,Nb,Ta)NxC1‐x

Compositionally complex transitional metal nitrides are possible candidates for ultra‐high temperature usage and are known for their superior properties due to the high configuration entropy. It is often difficult to synthesize pure metal nitrides in bulk, due to significant oxygen contamination; hence, they are synthesized mainly as thin films through magnetron sputtering, CVD or surface nitridation of high entropy alloys. The present paper reports on a single‐phase compositionally complex ceramic, i.e., (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)NxC1‐x, that was synthesized for the first time by employing an organometallic precursor route and using a double ammonolysis process. A multidisciplinary approach was performed to study these compositionally complex nitride and carbonitride systems, including experimental and theoretical investigations.This article is protected by copyright. All rights reserved.

Analysis of structural, electronic and optical properties of Er-doped rock salt AlN using ab-initio calculations.

This investigation includes the structural and optoelectronic characteristics of both pure and Er-doped rock salt aluminium nitride (AlN). Upon introducing Er doping into the AlN host, the calculations reveal a rise in the atomic parameter. Incorporating Er into the system leads to enhancements in the static dielectric coefficient ɛ1(0), static reflectivity R(0), as well as static refractive index n(0), at zero frequency. After doping, the peaks of imaginary dielectric tensor, extinction coefficient and absorption coefficient shift towards lower energy levels. Various exchange correlation potentials are incorporated to compare the results of electronic and optical characteristics. We employed the full potential linearized augmented plane wave (FP-LAPW) approach with WIEN2k code in conjunction with the density functional theory (DFT). To explore the optoelectronic characteristics of both pure as well as doped systems, three distinct exchange correlation potentials are utilized: the Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA), Modified Becke Johnson Generalized Gradient Approximations (mBJ + GGA) and Hubbard potential (GGA + U).

Theoretical study of adsorption of sodium, lithium, magnesium and calcium chloride and sulfate salts by pure and Sc-doped B12N12 nanocages and pure boron nitride nanosheet

High concentrations of water-soluble chloride and sulfate salts may cause adverse effects to humans and plants. Boron nitride (BN) nanostructures seem able to remove these water-soluble salts. In addition, Li+, Mg2+, Ca2+, and Na2+ interactions with BN nanostructures have received much attention in fabricating high-performance metal-ion batteries. Accordingly, this study investigated the adsorption of chloride and sulfate salts of Li, Mg, Ca, and Na on pristine and scandium (Sc)-doped B12N12 nanocages and pure BN nanosheet through DFT calculations. Optimizing the structures at the B3LYP/6-31 g (d, p) and M062X/6-311 g (d, p) computational levels indicated very exothermic chemisorption of chloride and sulfate salts on the pure and Sc-doped B12N12 nanocages. The B12N12-LiCl and Sc@B11N12-LiCl complexes showed the highest negative adsorption energies of −26.33 and −57.30 kcal/mol among the chloride salts. The B12N12-MgSO4 and Sc@B12N12-MgSO4 complexes showed the highest adsorption energies of −69.27 and −102.70 kcal/mol among the sulfate salts. Studying the effect of the adsorption process on the electronic properties of the B12N12 nanocage showed a reduction in the energy gap upon the adsorption of all salts on the pure B12N12 nanocage with the lowest energy gap of 3.98 eV for B12N12-MgSO4. The adsorption energies of the individual salts and their complexes on the B12N12 nanosheet at the B3LYP/6-311 g (d, p) level imply the occurrence of physisorption. A significant reduction was observed in the energy gap by adsorbing the salts on the BN nanosheet. Adsorbing CaSO4 and MgSO4 on the BN nanosheet caused the largest variation of 1.71 and 1.56 eV in the energy gap, respectively. The promising results of our study highlight the potential application of BN nanostructures in the removal of various soluble salts and the fabrication of metal-ion batteries.

Tailored Synthesis of CN-PPy Composite for Enhanced Electrochemical Functionality

This study details the synthesis of pure carbon nitride (CN) and composite polypyrrole through an in-situ polymerization method. The prepared samples were comprehensively characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Diffraction (XRD). These analyses confirmed the chemical bonding, structural, and morphological characteristics of the products. Electrochemical measurements, conducted through cyclic voltammetry (CV) and Linear Sweep Voltammetry (LSV), revealed significant current rates in both anodic and cathodic peaks, indicating superior electrochemical properties. This work not only details the synthesis process but also provides a thorough understanding of the structural, morphological, and electrochemical aspects, exhibiting the materials’ potential for various applications in electrochemical devices.

Photocatalytic efficient cleavage of C-C bond in lignin model using water as solvent

Photocatalytic lignin C-C bond (LCCD) cleavage is one possible strategy to promote high-value utilization of lignin. However, it still confronts many difficulties due to the stability of the lignin structure and the high activation energy of LCCD. Herein, a graphitic carbon nitride photocatalyst with the introduction of cyano groups and K+ ions (6MCN) is synthesized. Compared with pure carbon nitride (PCN), 6MCN exhibits superior photogenerated carrier separation ability, excellent sunlight capture ability, and greater oxidation capability. Under simulated sunlight, 6MCN significantly improves the photocatalytic efficiency of LCCD breakage in β-1 lignin models and aromatic vicinal diols (ACD), compared with earlier literature. The improved Cβ radical mechanism and single-electron transfer (SET) pathway are the primary mechanisms in the photocatalytic reaction. Hydroxyl radicals, superoxide radicals, and photogenerated holes are all involved in the photocatalytic cleavage of LCCD. However, hydroxyl radicals, as the most important active radicals, not only trigger the SET mechanism and Cβ radical mechanism but also provide the O and H atoms required for photocatalytic fracture of LCCD, which is very critical to obtain excellent photocatalytic efficiency. This work offers new insights into the photocatalytic breakage of LCCD in β-1 lignin models and ACD through the development of high-performance photocatalysts and the control of radical types.

Enhancing dielectric properties of ZnO nanopowders with 2D hBN doping: production, structural, morphological and dielectric characterization

In this study, it was aimed to improve the dielectric properties of ZnO nanoparticles with the addition of hBN, which was not previously available in the literature, and thus to expand their usage areas. Sol–gel synthesis method was used in this study to create pure and hexagonal boron nitride (hBN) doped zinc oxide (ZnO) nanoparticles. Zinc acetate dihydrate Zn(CH3COO)22H2O), sodium hydroxide NaOH, and hexagonal boron nitride (hBN), all from Sigma Aldrich, were used as starting reagents. The reagents were dissolved during the sol–gel synthesis by being heated to 90 °C for 4 h in a magnetic stirrer. FT-IR, XRD, FE-SEM, EDX characterization techniques, and impedance analyzer were used to find functional groups, structural, morphological, and chemical composition, and dielectric properties of the nanoparticles, respectively. The produced un-doped and hBN-doped ZnO particles consist of nano-sized structures. Changes occurred in the intensities and locations of the XRD diffraction peaks and FT-IR peaks with the addition of hBN. Characteristic peaks of both ZnO and hBN were observed in the diffraction peaks of the doped nanoparticles. All nanoparticles were of high purity and were successfully produced by the sol–gel method. It was shown that as the hBN doping level increased, there were more hBN nanoplates in the ZnO matrix, and the EDX results also showed an increase in hBN addition. The frequency stability of the dielectric properties improved after hBN doping. While the dielectric constant at 1 kHz frequency at room temperature is 12.07 in pure ZnO nanoparticles, the increase up to 55.21 is observed in 10% hBN doped nanocomposites. This situation is considered as a great potential for technological applications of this novel nanocomposite material.

The first-principles study of pure and doped g-CN nanosheet as a drug delivery system

Nanomaterials are increasingly being studied for their potential to serve as drug delivery systems that can transport anticancer drugs directly to tumor cells, thereby minimizing side effects and enhancing treatment effectiveness. This innovative application of nanotechnology holds significant promise in the field of biomedicine. Within the current piece of research, pure graphitic carbon nitride nanosheet (PC3NNS) and Si-doped C3NNS (C3NNS) were selected as a drug delivery system (DDS) for examining the distribution and bioavailability of 6-Mercaptopurine (6-MP) on cancerous cells through the DFT. After doping the Si atom, the attributes of PC3NNS changed, thereby increasing the adhesion process of 6-MP. The adhesion energy of the Si@C3NNS was in the range of 5.5 eV, which demonstrated that it was highly stable. The current work demonstrated the poor adhesion of 6-MP on the PC3NNS with the adhesion energy of approximately −1.72 eV and −2.83 eV in water and gaseous phases respectively. The adhesion energy increased by around 96.21 % after the Si atom was doped on the PC3NNS. The non-covalent interaction (NCI) analysis and the reduced density gradient (RDG) map analysis were performed to examination the main interactions between nanosheet and drug. It was demonstrated that NCIs played a key role in the adhesion of 6-MP in the complex of 6-MP@Si-C3N. Moreover, the NCI analysis demonstrated the significant impact of van der Waals interactions upon the interactions between 6-MP and the nanosheets. The current work can provide insights into the application of C3NNSs as promising drug carriers for many drugs in targeted DDSs.

Multicolour room temperature phosphorescence of carbon nitride nanoparticles in sodium borohydride and borax matrix

Carbon nitride based materials find applications in photocatalysis, sensing, and bioimaging. The fluorescence properties of carbon nitride based nanomaterials is widely studied. However, its phosphorescence phenomenon is relatively less explored. Herein, we report a simple and economic one step thermal synthesis of highly fluorescent pure carbon nitride nanoparticles (CNNPs) from organic solvent formamide at 220 °C, just above its boiling point without any further passivation or purification.The fluorescent CNNPs is dispersed in sodium borohydride and borax which act as suitable host matrix resulting in activation of persistent room temperature phosphorescence of CNNPs with high phosphorescence lifetimes of 1.144 s and 0.737 s respectively. Moreover, the CNNPs-Sodium borohydride composite display tricolour, blue, green and yellow-orange phosphorescence under 254 nm, 365 nm and 400 nm light respectively while CNNPs-Borax composite show dual blue and green phosphorescence under 254 nm and 365 nm UV light respectively. Hence, these CNNPs-Composite may be used as multicolour anti-counterfeiting materials in future.

High-quality nanocavities through multimodal confinement of hyperbolic polaritons in hexagonal boron nitride.

Compressing light into nanocavities substantially enhances light-matter interactions, which has been a major driver for nanostructured materials research. However, extreme confinement generally comes at the cost of absorption and low resonator quality factors. Here we suggest an alternative optical multimodal confinement mechanism, unlocking the potential of hyperbolic phonon polaritons in isotopically pure hexagonal boron nitride. We produce deep-subwavelength cavities and demonstrate several orders of magnitude improvement in confinement, with estimated Purcell factors exceeding 108 and quality factors in the 50-480 range, values approaching the intrinsic quality factor of hexagonal boron nitride polaritons. Intriguingly, the quality factors we obtain exceed the maximum predicted by impedance-mismatch considerations, indicating that confinement is boosted by higher-order modes. We expect that our multimodal approach to nanoscale polariton manipulation will have far-reaching implications for ultrastrong light-matter interactions, mid-infrared nonlinear optics and nanoscale sensors.

Exploring the sensing potential of Fe-decorated h-BN toward harmful gases: a DFT study.

Gas sensing technology has a broad impact on society, ranging from environmental and industrial safety to healthcare and everyday applications, contributing to a safer, healthier, and more sustainable world. We studied pure and Fe-decorated hexagonal boron nitride (h-BN) gas sensor for monitoring of carbon-based gases using density functional theory (DFT). The calculations utilized the Generalized Gradient Approximation with the Perdew-Burke-Ernzerhof (GGA-PBE) exchange-correlation functional. The novelty of our study lies in the investigation of the adsorption of harmful gases such as carbonyl sulfide, carbinol, carbimide, and carbonyl fluoride on both pure and Fe-decorated h-BN. The deviation in structural, electronic, and adsorption properties of h-BN due to Fe decoration has been studied along with the sensing ability to design said material towards carbon monoxide (CO), carbon dioxide (CO2), carbonyl sulfide (COS), carbinol, (CH4O), carbimide (CH2N2), and carbonyl fluoride (CF2O) gases. Gases such as CO, COS, CH2N2, and CF2O exhibited chemisorption, while CO2, and CH4O exhibited physisorption behavior. The introduction of Fe altered the semiconductor properties of h-BN and rendered it metallic. Enhanced electronic properties were observed due to a robust hybridization occurring between the d-orbitals of Fe-decorated BN and the gas molecules. The extended recovery periods observed for gases, aside from CO2, indicate their adhesive interactions with Fe-decorated h-BN. The reduction in desorption duration as temperature rises allows Fe-decorated h-BN to function as a reversible gas sensor. This research opens up a novel pathway for the synthesis and advancement of cost-effective, environmentally friendly double-atom catalysts with high sensitivity for capturing and detecting molecules such as CO, COS, CH2N2, CO2, CH4O, and CF2O.

Bi-directional charge transfer channels in highly crystalline carbon nitride enabling superior photocatalytic hydrogen evolution.

Introducing a donor-acceptor (D-A) unit is an effective approach to facilitate charge transfer in polymeric carbon nitride (PCN) and enhance photocatalytic performance. However, the introduction of hetero-molecules can lead to a decrease in crystallinity, limiting interlayer charge transfer and inhibiting further improvement. In this study, we constructed a novel D-A type carbon nitride with significantly higher crystallinity and a bi-directional charge transfer channel, which was achieved through 2,5-thiophenedicarboxylic acid (2,5-TDCA)-assisted self-assembly followed by KCl-templated calcination. The thiophene and cyano groups introduced serve as the electron donor and acceptor, respectively, enhancing in-plane electron delocalization. Additionally, introduced potassium ions are intercalated among the adjacent layers of carbon nitride, creating an interlayer charge transfer channel. Moreover, the highly ordered structure and improved crystallinity further facilitate charge transfer. As a result, the as-prepared photocatalyst exhibits superior photocatalytic hydrogen evolution (PHE) activity of 7.449 mmol h-1 g-1, which is 6.03 times higher than that of pure carbon nitride. The strategy of developing crystalline D-A-structured carbon nitride with controlled in-plane and interlayer charge transfer opens new avenues for the design of carbon nitride with enhanced properties for PHE.