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Graphitic-phase carbon nitride (g-C 3 N 4) for water oxidation are rarely reported. Herein, ultrathin g-C 3 N 4 insert between OEC (NiOOH, FeOOH, CoPi and CoOOH) and BiVO 4 photoanode can enhance the photoelectrochemical performance of the optimized OEC/BiVO 4 system. Ultrathin g-C 3 N 4 layers can effectively optimize photo-holes migration routes on the BiVO 4 -based photoanode/liquid interface to enforce directional holes extraction and transfer, thus prolonging holes trapping lifetime. More specifically, the effect of thickness on holes extraction is revealed and the thickness of ultrathin g-C 3 N 4 layers is optimized. A photocurrent density of 4.20 mA cm −2 (1.23 V vs. RHE) is achieved by CoOOH/g-C 3 N 4 /BiVO 4 , which is 4.29 times higher than pure BiVO 4. The applied bias photon-to-current efficiency achieves 1.65% at 0.62 V vs. RHE, which is 10.31 times compared with pristine BiVO 4 (0.16%, 0.89 V vs. RHE). This work shed light on design and fabrication of the BiVO 4 -based photoanode interface for application in solar light to fuel conversion. [Display omitted] • Ultrathin g-C 3 N 4 layers enforced directional holes extraction and transfer. • The effect of thickness was revealed and the optimum thickness was determined. • A photocurrent density of 4.20 mA cm−2 was achieved by CoOOH/g-C 3 N 4 /BiVO 4. • The photocurrent density was 4.29 times higher than pure BiVO 4. • Ultrathin g-C 3 N 4 was excellent hole extraction material for BiVO 4 -based photoanodes. [ABSTRACT FROM AUTHOR]

The present study deals with the synthesis, characterization, and testing of g-C 3 N 4 -PANI-PPy nanohybrids for electrochemical and photocatalytic studies. For the formation of nanohybrids, the chemical oxidative method was employed and was thoroughly characterized for the surface, functional, and elemental properties by making use of different instrumental techniques like XRD, XPS, FTIR, UV-Vis, Raman, FESEM, HRTEM, and EDAX. On testing of the electrochemical sensing properties, we found that the g-C 3 N 4 -PANI-PPy modified glassy carbon electrode (GCE) exhibited satisfactory results for the mebendazole drug detection and is supported by the formation of layer and donor-acceptor behavior corresponding to the electrochemical cyclic stability. Further, the g-C 3 N 4 -PANI-PPy nanohybrid investigated to have high photocatalytic performance towards the degradation of organic dye, methylene blue, and is supported by the enhanced specific surface area and transition of surface electrons. Finally, with such beneficial features of electrochemical sensitivity and great catalytic activity, the developed g-C 3 N 4 -PANI-PPy hybrid can find applications in the analytical laboratories and also catalysis research. ga1 • Chemical linking of g-C 3 N 4 with that of PANI and PPy generated g-C 3 N 4 -PANI-PPy nanohybrids. • The nanohybrids active towards multiple application sites of electrochemical detection of mebendazole drug and photocatalytic degradation of MB. • The detection limit and quantitation limits of mebendazole are 0.1481 µM µA−1 and 0.4717 µM µA−1. • The photocatalytic degradation of MB dye provided the maximum efficiency of 95.5%. • These significant results confirm for the potential applications of g-C 3 N 4 -PANI-PPy nanohybrids as electrode and photocatalyst material. [ABSTRACT FROM AUTHOR]

• CuS/g-C 3 N 4 and CuS/h-BN nanocomposites are synthesized by simple hydrothermal technique. • The nanocomposites exhibit superior peroxidase like activity and catalyze the oxidation of TMB. • Presence of Ibuprofen hinders the TMB oxidation process by scavenging the OH radicals. • Ibuprofen can be detected upto 16.01 and 21.20 mg/L using CuS/g-C 3 N 4 and CuS/h-BN respectively. This work reports a selective and sensitive method for detection of Ibuprofen (Ibu), a nonsteroidal anti-inflammatory drug (NSAID) based on the peroxidase mimic activity of CuS nanoparticles (NPs) decorated on 2D graphitic carbon nitride (g-C 3 N 4) and hexagonal boron nitride nanosheets (h-BN). CuS/g-C 3 N 4 and CuS/h-BN nanocomposites are synthesized by simple hydrothermal technique and characterized by different sophisticated analytical techniques like XRD, BET, HRTEM and XPS analysis. The surface charge of the nanocomposites is determined by zeta potential analysis. The peroxidase mimic activity of the nanocomposites are analyzed by carry out the catalytic oxidation of 3, 3ʹ, 5, 5ʹ-tetramethylbenzidine (TMB) in presence of H 2 O 2 to produce a blue colored oxidized product (oxTMB). The synthesized nanocomposites are employed for the colorimetric detection of Ibu a model pharmaceutical pollutant in an aqueous medium. Ibu is commonly used by human beings to cure certain ailments and excreted in environmental wastewaters that have several bad effects. The principle of sensing is the inhibition of the peroxidase mimic activity of the nanozymes by Ibu. The detection limit of Ibu achieved in the colorimetric detection technique is found to be 16.01 and 21.20 mg/L (ppm) within the linear range of 0−100 mg/L in presence of CuS/g-C 3 N 4 and CuS/h-BN nanocomposites, respectively. The practical application of the proposed sensor is successfully demonstrated using various environmental water samples spiked with different concentrations of Ibu. The proposed sensing probes exhibit high specificity and anti-interfering ability over other water contaminates and considerable feasibility in real water systems. [ABSTRACT FROM AUTHOR]

• Deposition of highly ordered g-C 3 N 4 film via thermal CVD. • Anisotropic transport characteristics depending on the crystal orientation. • Indication of p -type behavior from the contact interfaces. • g-C 3 N 4 based SBD as a vertical electronic device. The electronic transport characteristics of crystalline g-C 3 N 4 film and its device application were investigated. Crystalline g-C 3 N 4 films ordered along the c -axis were formed via thermal chemical vapor deposition using melamine source. The chemical bonds of the film were confirmed to be the bond states that constitutes g-C 3 N 4. In addition, the stoichiometric N/C ratio was estimated as 1.17 from the C1s and N1s signal intensities of X-ray photoelectron spectroscopy. A typical photoluminescence and Raman spectra of the g-C 3 N 4 film was detected. Anisotropic transport characteristics with a dependence on the crystal orientation were observed, resulting in a high out-of-plane conductivity and a low in-plane conductivity. A Schottky barrier diode with a Au anode and Ti/Au cathode was fabricated as a vertical electronic device. Rectifying behavior was achieved for the diode, suggesting possibilities of electronic device applications of g-C 3 N 4. [ABSTRACT FROM AUTHOR]

• C-doped CuO/g-C 3 N 4 was prepared via facile, one-pot method using low-cost precursors. • Photocathodes were directly deposited on FTO substrate under microwave irradiation. • The amount of urea determined the microstructure of CuO and its optical properties. • Superiority of our synthesis method over many other solution-based ones is explored. • Mechanisms for heterojunction formation and PEC performance improvement are proposed. Cupric oxide (CuO) is a semiconductor of choice for photocathode in photoelectrochemical (PEC) applications due to its great sunlight absorption capability. However, photocorrosion is the main drawback of CuO. Herein, CuO/graphitic carbon nitride (g-C 3 N 4) with a unique microstructure, enhanced PEC performance, and considerable photostability is synthesized under microwave irradiation. A facile, one-pot method is utilized to directly deposit the nanocomposite onto fluorine-doped tin oxide from a solution containing copper precursor and urea. Possible mechanism of CuO/g-C 3 N 4 formation through this novel method is investigated. It is elucidated that controlled amounts of urea critically determine the morphological evolution of CuO, while its excess quantities convert to g-C 3 N 4 in the presence of CuO as the catalyst. Through an appropriate heat treatment, carbon is doped into CuO lattice. The obtained C-doped CuO/g-C 3 N 4 demonstrates 227% enhancement over CuO in photocurrent density and ~80% photocurrent retention. The enhanced photoelectrocatalytic activity is mainly attributed to unique morphology of CuO, effective separation of charge carriers, and formation of heterojunction. These characteristics manifest the superiority of this approach over many other chemical-based methods. The nanocomposite synergistically integrates the advantages of both the constituents, offering a low-cost, efficient photocathode for PEC water splitting, photocatalytic hydrogen evolution, and degradation of pollutants. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) is a two-dimensional conjugated polymer that has attracted the interest of researchers and industrial communities owing to its outstanding analytical merits such as low-cost synthesis, high stability, unique electronic properties, catalytic ability, high quantum yield, nontoxicity, metal-free, low bandgap energy, and electron-rich properties. Notably, graphitic carbon nitride (g-C3N4) is the most stable allotrope of carbon nitrides. It has been explored in various analytical fields due to its excellent biocompatibility properties, including ease of surface functionalization and hydrogen-bonding. Graphitic carbon nitride (g-C3N4) acts as a nanomediator and serves as an immobilization layer to detect various biomolecules. Numerous reports have been presented in the literature on applying graphitic carbon nitride (g-C3N4) for the construction of electrochemical sensors and biosensors. Different electrochemical techniques such as cyclic voltammetry, electrochemiluminescence, electrochemical impedance spectroscopy, square wave anodic stripping voltammetry, and amperometry techniques have been extensively used for the detection of biologic molecules and heavy metals, with high sensitivity and good selectivity. For this reason, the leading drive of this review is to stress the importance of employing graphitic carbon nitride (g-C3N4) for the fabrication of electrochemical sensors and biosensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal-free heterogeneous catalysts developed for the synthesis of cyclic carbonate. • Hydroxyl-functionalized eg-C 3 N 4 materials prepared through a simple HCl treatment. • More convenient to be prepared than other reported g-C 3 N 4 -based catalysts. • High catalytic activity and stable recycling performance. Graphitic carbon nitride (g-C 3 N 4) contains abundant nitrogen-containing groups and have demonstrated potential catalysis in several CO 2 -activating reactions. However, the catalytic activity obtained with the bulk and pristine g-C 3 N 4 is quite low. In this work, g-C 3 N 4 was prepared using dicyandiamide as a precursor, thermally exfoliated, and then treated by HCl solution. The synthesized eg-C 3 N 4 −OH were analyzed by various characterization techniques including XRD, N 2 adsorption, SEM, FT-IR, UV–vis, XPS, and Raman spectroscopy. The characterization results confirmed that the treatment of HCl induced the generation of hydroxyl groups on the surface of eg-C 3 N 4 , depending on the treatment conditions. As metal-free catalysts, the eg-C 3 N 4 materials exhibit high catalytic activities in the cycloaddition reactions of CO 2. The effects of HCl treatment on the chemical properties of eg-C 3 N 4 materials and the corresponding catalytic performance have been investigated. Furthermore, the catalytic performance of eg-C 3 N 4 −OH was compared with other previously reported g-C 3 N 4 -based materials. [ABSTRACT FROM AUTHOR]

In this work, surface modification of graphitic carbon nitride (g-C 3 N 4) nanoflakes is achieved by polyindole (PIn) without using any surfactant via in-situ chemical polymerization. The electro capacitive properties of the materials are directly related to their surface functionalities, microstructure, and interfacial interaction. Therefore, the interface engineering of g–C 3 N 4 –PIn nanohybrid is performed to improve the electrochemical activity. The optimal composition of g–C 3 N 4 –PIn nanohybrids is investigated by varying amounts of indole monomer (5, 20 and 50 mg) with a fixed weight of g-C 3 N 4 (10 mg) during polymerization. Various spectroscopic/microscopic techniques identify the as-synthesized nanohybrids before exploring their application as metal-free electrode material. In comparison (current density at 2 Ag−1), the 1:2 g–C 3 N 4 –PIn nanohybrid exhibits better electrochemical performance over the others. The specific capacitance (Cs) values are estimated as 115.8 Fg−1for 1:2 g–C 3 N 4 –PIn and 12.4, 38.7, 21.5, and 66.9 F g-1, for bare g-C 3 N 4 , pure PIn, and other two nanohybrids (1:0.5 and 1:5) of g–C 3 N 4 –PIn respectively. In this article, the 1:2 g–C 3 N 4 –PIn nanohybrid is an optimal weight ratio and advances in strategies on the metal-free and binder-free electrodes with the fast diffusion process of charges. It shows 96% cycling stability over 250 cycles. Image 1 • Surface modification of graphitic carbon nitride (g-C 3 N 4) nanoflakes with polyindole. • Electrochemical performance of materials depend on their structure and interfacial interaction. • Synergistic effect only up to a certain ratio of parental counterparts. • A metal-free electrode material for electrochemical applications such as supercapacitor. [ABSTRACT FROM AUTHOR]

The issue of insufficient freshwater resources has become a worldwide problem, restricting social and economic development. As a promising technology, capacitive deionization (CDI) has been developed to address this problem. In this work, MoS 2 /g-C 3 N 4 composite with a high supercapacitor performance was successfully synthesized and assembled as the CDI electrode material with its electrochemical properties deeply evaluated. The results demonstrated that the MoS 2 /g-C 3 N 4 -based electrode demonstrated a large specific capacitance of 118.3 F/g (at 1 A/g) and a remarkable rate capacitance retention of 52.16% (61.7 F/g) (at 10 A/g). Moreover, the MoS 2 /g-C 3 N 4 -based electrode exhibited obvious improvement in desalination performance with the maximum electrosorption capacity of 24.5 mg/g. The hierarchical architecture, enhanced conductivity, large surface area, and negative zeta potential of MoS 2 /g-C 3 N 4 composite facilitated the fast diffusion of ions. The enhanced ions adsorption performance of the MoS 2 /g-C 3 N 4 -based electrode was evaluated based on a capacitive contribution of 85.26% and a diffusion-controlled contribution of 14.74%. Unlabelled Image • MoS 2 /g-C 3 N 4 composite with a high supercapacitor performance is synthesized. • MoS 2 /g-C 3 N 4 electrode exhibits an electrosorption capacity of 24.2 mg/g. • Capacitive and diffusion-controlled processes contribute to the salt storage. • Capacitive-controlled process dominates the contribution (85.26%). • A good regeneration performance is demonstrated. [ABSTRACT FROM AUTHOR]

In the 21st century, the development of sustainable energy and advanced technologies to cope with energy shortages and environmental pollution has become vital. Semiconductor photocatalysis is a promising technology that can directly convert solar energy to chemical energy and is extensively used for its environmentally-friendly properties. In the field of photocatalysis, graphitic carbon nitride (g-C3N4) has obtained increasing interest due to its unique physicochemical properties. Therefore, numerous researchers have attempted to integrate quantum dots (QDs) with g-C3N4 to optimize the photocatalytic activity. In this review, recent progress in combining g-C3N4 with QDs for synthesizing new photocatalysts was introduced. The methods of QDs/g-C3N4-based photocatalysts synthesis are summarized. Recent studies assessing the application of photocatalytic performance and mechanism of modification of g-C3N4 with carbon quantum dots (CQDs), graphene quantum dots (GQDs), and g-C3N4 QDs are herein discussed. Lastly, challenges and future perspectives of QDs modified g-C3N4-based photocatalysts in photocatalytic applications are discussed. We hope that this review will provide a valuable overview and insight for the promotion of applications of QDs modified g-C3N4 based-photocatalysts. [ABSTRACT FROM AUTHOR]

The ubiquity of micropollutants (MPs) in aquatic environments has attracted increasing concern for public health and ecological security. Compared to conventional biological treatment, photocatalytic processes show more efficiency in degrading MPs, but they require expensive materials and complicated synthesis processes. This study developed an economic photocatalytic process to degrade micropollutants. We synthesized urea-based graphitic carbon nitride (g-C 3 N 4 ) by a facile one-step pyrolysis method and evaluated the photocatalytic efficiency of carbamazepine (CBZ). Under simulated solar irradiation, g-C 3 N 4 could achieve 100% removal efficiency of 0.1 mg/L CBZ in spiked wastewater effluent within 15 min, and 86.5% removal efficiency in wastewater influent after 20 min of irradiation. The porous structure of g-C 3 N 4 promoted effective charge separation and mass transport of CBZ near the catalyst surface, enabling a high kinetic rate (0.3662 min -1 ). Reactive oxygen species trapping experiments revealed that superoxide radicals (O 2 •- ) and holes (h + ) were the major active radicals. Electron paramagnetic resonance (EPR) further confirmed the presence of O 2 •- , • OH, 1 O 2 and holes. The pH, light intensity and initial CBZ concentration were found to have significant impacts on the removal efficiency of CBZ. Possible reaction intermediates were identified and the degradation pathway was proposed. Multiple MPs were selected to further demonstrate photocatalytic efficiency of g-C 3 N 4 . The facile synthesis, superior efficiency, and versatility of g-C 3 N 4 make it a promising catalyst for application in tertiary wastewater treatment processes., Competing Interests: The authors declare that they have no conflict of interest., (© 2021 The Authors.)

The methodology of metal-involved preparation for carbon materials is favored by researchers and has attracted tremendous attention. Decoupling this process and the underlying mechanism in detail are highly required. Herein, the intrinsic mechanism of carbon fixation in graphitic carbon nitride (g-C 3 N 4 ) via the magnesium-involved carbonization process is reported and clarified. Magnesium can induce the displacement reaction with the small carbon nitride molecule generated by the pyrolysis of g-C 3 N 4 , thus efficiently fixing the carbon onto the in situ template of Mg 3 N 2 product to avoid the direct volatilization. As a result, the N-doped carbon nanosheet frameworks with interconnected porous structure and suitable N content are constructed by reconstruction of carbon and nitrogen species, which exhibit a comparable photoelectric conversion efficiency (8.59%) and electrocatalytic performances to that of Pt (8.40%) for dye-sensitized solar cells., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

As a new type of non-metallic material, graphite carbon nitride (g-C 3 N 4 ) has attracted increasing attention due to its inherent advantages such as simple preparation, excellent thermal and chemical stability, as well as good biocompatibility and non-toxicity. Nowadays, g-C 3 N 4 is widely used in electrocatalysis, photocatalysis, biological imaging, and so on. Because of its large specific surface area, π -electron-rich structure, and hydrophobic properties, g-C 3 N 4 is considered an ideal candidate material for sample pretreatment. In this work, g-C 3 N 4 and its composites as potential sorbents for solid-phase extraction, dispersive solid-phase extraction, magnetic solid-phase extraction, and solid-phase microextraction are reviewed, and the future trends and prospective are discussed.

A g-C 3 N 4 /Mo:BiVO 4 (CMB) heterojunction photoanode is constructed with enhanced photoelectrochemical (PEC) water oxidation performance, in which ultrathin g-C 3 N 4 is coated on Mo-doped BiVO 4. CMB shows a remarkable water oxidation photocurrent of 3.11 mA cm−2 at 1.23 V vs. RHE, which is 3.21 times higher than pristine BiVO 4. The maximal incident photon-to-current efficiency (IPCE) reaches 45.5% at 430 nm and the applied bias photo-to-current efficiency (ABPE) reaches 0.74% at 0.78 V vs. RHE, which are 2.62 and 5.76 times compared with pristine BiVO 4 , respectively. The amounts of hydrogen and oxygen generated by CMB are 18.58 and 9.32 μmol within 1 h, which are 4.66 and 5.51 times higher than pristine BiVO 4. The significant enhancements are attributed to the improvement of charge separation and acceleration of oxygen evolution reaction (OER) kinetics. Mo-dopant enhances charge separation due to its excellent electron transfer capability. Ultrathin g-C 3 N 4 also boosts charge separation via forming a heterojunction with Mo:BiVO 4 and promotes OER kinetics by accelerating the transfer of holes to the photoelectrode surface. The work testifies the promise of combing metal-doping with constructing heterojunctions using ultrathin g-C 3 N 4 to enhance water oxidation performance, and provides an excellent reference for designing and constructing efficient photoanodes for PEC water oxidation. • A new photoanode CMB was obtained by coating ultrathin g-C 3 N 4 on Mo:BiVO 4. • CMB showed higher PEC water oxidation performance than most BiVO 4 -based photoanodes. • Mo-dopant enhanced charge separation due to its electron transfer capability. • Ultrathin g-C 3 N 4 promoted charge separation and OER kinetics. • Combing metal-doping with constructing heterojunction had potential for photoanodes. [ABSTRACT FROM AUTHOR]

In article number 1803186, by Wei Lv, Quan‐Hong Yang, and co‐workers, the rainbow ring inside the 3D network is shown to be indicative of the micro‐electric field (MEF) induced by graphitic carbon nitride nanosheets that are used for uniform lithium nucleation and subsequent growth. The MEF serves as an electronic "tornado" with a strong attraction to capture Li ions and significantly reduces the Li nucleation overpotential. [ABSTRACT FROM AUTHOR]

Uncontrolled dendrites resulting from nonuniform lithium (Li) nucleation/growth and Li volume expansion during charging cause serious safety problems for Li anode‐based batteries. Here the coating of nickel foam with graphitic carbon nitride (g‐C3N4) to have a 3D current collector (g‐C3N4@Ni foam) for dendrite‐free Li metal anodes is reported. The lithiophilic g‐C3N4 coupled with the 3D framework is demonstrated to be highly effective for promoting the uniform deposition of Li and suppressing the formation of dendrites. Both density functional theory calculations and experimental studies indicate the formation of a micro‐electric field resulting from the tri‐s‐triazine units of g‐C3N4, which induces numerous Li nuclei during the initial nucleation stage, effectively guiding the following Li growth on the 3D Ni foam to be well distributed. Furthermore, the 3D porous framework is favorable for absorbing any volume change and stabilizing the solid–electrolyte interphase layer during repeated Li plating/stripping. As such, a Li metal anode based on the g‐C3N4@Ni foam has a remarkable electrochemical performance with a high Coulombic efficiency (98% retention after 300 cycles), an ultralong lifespan up to 900 h, as well as a low overpotential (<15 mV at 1.0 mA cm−2) at a Li deposition of 9.0 mA h cm−2. Graphitic carbon nitride (g‐C3N4)‐coated nickel foam is demonstrated to be highly effective for promoting uniform lithium deposition. The unique micro‐electric field at the tri‐s‐triazine units of g‐C3N4 induces numerous Li nuclei at initial nucleation stage and, subsequently, these Li nuclei guide well‐distributed Li plating on 3D Ni foam. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C₃N₄) is a promising semiconductor material which has been widely studied in nanoscience. However, the effect of modifying the performance of g-C₃N₄ is still under debate. In this communication, we show the size and functional group effects on the g-C₃N₄ using density functional theory (DFT) calculations. It was found that a molecule with six repeated g-C₃N₄ units (g-C₃N₄-6) could be the smallest unit that converges to the limit of its HOMO⁻LUMO gap. Calculations of g-C₃N₄-6 with varying numbers of substituted C≡N, C=O, and O-H functional groups show that C≡N and C=O could narrow down the HOMO⁻LUMO gap, while O-H could slightly raise the gap. This study shows that the change of substituents could tune the band gap of g-C₃N₄, suggesting that rationally modifying the substituent at the edge of g-C₃N₄-based materials could help to significantly increase the photocatalytic properties of a metal-free g-C₃N₄.

Delamination treatment is crucial in promoting the activity of bulk graphitic carbon nitride (g-C 3 N 4 ). However, most of the currently used methods of exfoliating bulk g-C 3 N 4 to achieve g-C 3 N 4 thin layers suffer from low yield and environmental pollution. Herein, we developed a facile bacterial etching approach for the preparation of high-quality g-C 3 N 4 nanosheets by exfoliating bulk g-C 3 N 4 under room temperature. Morphology and physicochemical characterizations show that the bacteria-treated g-C 3 N 4 (BT-CN) samples, especially BT-CN-2d, have a lamina-like two-dimensional (2D) in-plane porous structure, a significantly enlarged specific surface area (82.61 m 2 g -1 ), and a remarkable narrow band gap (2.11 eV). X-ray photoelectron spectroscopy and electron paramagnetic resonance spectra confirm the dramatic enrichment of unpaired electron in the BT-CN-2d g-C 3 N 4 nanosheets. EIS spectra and photocurrent tests indicate the fast electron transportation. As a result, the representative BT-CN-2d g-C 3 N 4 photocatalyst shows an optimal visible light-driven photocatalytic performance in water disinfection (fourfold higher than bulk g-C 3 N 4 ), as well as good cycle stability. This moderate and clean bacterial etching process can be realized in tens of gram scale in the laboratory and should be readily extended to kilogram scale. The present work provides fundamental knowledge about the scalable production of high-quality g-C 3 N 4 by bioengineering method, offering extendable availability for designing and fabricating other functional 2D materials.

A novel graphitic carbon nitride (g-C 3 N 4 )-CaTiO 3 (CTCN) organic-inorganic heterojunction photocatalyst was synthesized by a facile mixing method, resulting in the deposition of CaTiO 3 (CT) nanoflakes onto the surface of g-C 3 N 4 nanosheets. The photocatalytic activity of the as-synthesized heterojunction (along with the controls) was evaluated by studying the degradation of an aqueous solution of rhodamine B (RhB) under UV, visible and natural sunlight irradiation. The CTCN heterojunction with 1:1 ratio of g-C 3 N 4 /CT showed the highest photocatalytic activity under sunlight irradiation and was also demonstrated to be effective for the degradation of a colorless, non-photosensitizing pollutant, bisphenol A (BPA). The superior photocatalytic performance of the CTCN heterojunction could be attributed to the appropriate band positions, close interfacial contact between the constituents and extended light absorption (both UV and visible region), all of which greatly facilitate the transfer of photogenerated charges across the heterojunction and inhibit their fast recombination. In addition, the two-dimensional (2D) morphology of g-C 3 N 4 nanosheets and CT nanoflakes provides enough reaction sites due to their larger surface area and enhances the overall photocatalytic activity. Furthermore, the active species trapping experiments validate the major role played by superoxide radicals (O 2 -• ) in the degradation of pollutants. Based on scavenger studies and theoretically calculated band positions, a plausible mechanism for the photocatalytic degradation of pollutants has been proposed and discussed.

A biomolecule-assisted pyrolysis method has been developed to synthesize sulfur-doped graphitic carbon nitride (CNS) nanosheets. During the synthesis, sulfur could be introduced as a dopant into the lattice of carbon nitride (CN). Sulfur doping changed the texture as well as relative band positions of CN. By growing CN on preformed sulfur-doped CN nanosheets, composite CN/CNS heterojunction nanosheets were constructed, which significantly enhanced the photoelectrochemical performance as compared with various control counterparts including CN, CNS and physically mixed CN and CNS (CN+CNS). The enhanced photoelectrochemical performance of CN/CNS heterojunction nanosheets could be ascribed to the efficient separation of photoexcited charge carriers across the heterojunction interface. The strategy of designing and preparing CN/CNS heterojunction photocatalysts in this work can open up new directions for the construction of all CN-based heterojunction photocatalysts.