Recent Developments in Graphitic Carbon Nitride Based Hydrogels as Photocatalysts

Fluorescent Graphitic Carbon Nitride (g-C3N4)-Embedded Hyaluronic Acid Microgel Composites for Bioimaging and Cancer-Cell Targetability as Viable Theragnostic

Fluorescent graphitic carbon nitride (g-C3N4) doped with various heteroatoms, such as B, P, and S, named Bg-C3N4, Pg-C3N4, and Sg-C3N4, were synthesized with variable band-gap values as diagnostic materials. Furthermore, they were embedded within hyaluronic acid (HA) microgels as g-C3N4@HA microgel composites. The g-C3N4@HA microgels had a 0.5-20 μm size range that is suitable for intravenous administration. Bare g-C3N4 showed excellent fluorescence ability with 360 nm excitation wavelength and 410-460 emission wavelengths for possible cell imaging application of g-C3N4@HA microgel composites as diagnostic agents. The g-C3N4@HA-based microgels were non-hemolytic, and no clotting effects on blood cells or cell toxicity on fibroblasts were observed at 1000 μg/mL concentration. In addition, approximately 70% cell viability for SKMEL-30 melanoma cells was seen with Sg-C3N4 and its HA microgel composites. The prepared g-C3N4@HA and Sg-C3N4@HA microgels were used in cell imaging because of their excellent penetration capability for healthy fibroblasts. Furthermore, g-C3N4-based materials did not interact with malignant cells, but their HA microgel composites had significant penetration capability linked to the binding function of HA with the cancerous cells. Flow cytometry analysis revealed that g-C3N4 and g-C3N4@HA microgel composites did not interfere with the viability of healthy fibroblast cells and provided fluorescence imaging without any staining while significantly decreasing the viability of cancerous cells. Overall, heteroatom-doped g-C3N4@HA microgel composites, especially Sg-C3N4@HA microgels, can be safely used as multifunctional theragnostic agents for both diagnostic as well as target and treatment purposes in cancer therapy because of their fluorescent nature.

Impact of nitrogen doping on triazole-based graphitic carbon Nitride-TiO2 (P25) S-scheme heterojunction for improved photocatalytic hydrogen production

Establishing an S-scheme heterojunction is a promising method for increasing the photocatalytic activity of synthetic materials. In this study, nitrogen-doped g-C3N5/TiO2 S-scheme photocatalysts have been synthesized and examined for photocatalytic hydrogen production using thermal decomposition methods. Nitrogen-doped g-C3N5/TiO2 composites performed better than pure nitrogen-doped g-C3N5 and TiO2 alone. Using experiments and density functional theory (DFT) calculations, nitrogen (N) doping was identified as being introduced by replacing the carbon (C) atoms in the matrix of g-C3N5. In addition to its narrow band gap, N-doped g-C3N5 showed efficient carrier separation and charge transfer, resulting in the enhanced absorption of visible light and photocatalytic activity. DFT, XPS, optical property characteristics, and PL spectra confirmed these findings, which were attributed to the successful nitrogen doping, and the composite was proven to be a potential candidate for photocatalytic hydrogen generation under light irradiation. The quantity of H2 produced from the nitrogen-doped g-C3N5/TiO2 composite for 3 hours (3515.1 μmol g-1) was about three times that of N-doped g-C3N5. The H2 production percentage of the nitrogen-doped g-C3N5/TiO2 catalyst with Pt as the cocatalyst was improved by nearly ten times as compared to N-doped g-C3N5/TiO2 without a cocatalyst. Herein, we report the successful preparation of the N-doped g-C3N5/TiO2 S-scheme heterojunction and highlight a simple and efficient catalyst for energy storage requirements and environmental monitoring.

Recent Advances in g-C3N4-Based Photocatalysts for NOx Removal

Nitrogen oxides (NOx) pollutants can cause a series of environmental issues, such as acid rain, ground-level ozone pollution, photochemical smog and global warming. Photocatalysis is supposed to be a promising technology to solve NOx pollution. Graphitic carbon nitride (g-C3N4) as a metal-free photocatalyst has attracted much attention since 2009. However, the pristine g-C3N4 suffers from poor response to visible light, rapid charge carrier recombination, small specific surface areas and few active sites, which results in deficient solar light efficiency and unsatisfactory photocatalytic performance. In this review, we summarize and highlight the recent advances in g-C3N4-based photocatalysts for photocatalytic NOx removal. Firstly, we attempt to elucidate the mechanism of the photocatalytic NOx removal process and introduce the metal-free g-C3N4 photocatalyst. Then, different kinds of modification strategies to enhance the photocatalytic NOx removal performance of g-C3N4-based photocatalysts are summarized and discussed in detail. Finally, we propose the significant challenges and future research topics on g-C3N4-based photocatalysts for photocatalytic NOx removal, which should be further investigated and resolved in this interesting research field.

Aluminum Cation Doping in Ruddlesden-Popper Sr2TiO4 Enables High-Performance Photocatalytic Hydrogen Evolution

Hydrogen (H2) is regarded as a promising and renewable energy carrier to achieve a sustainable future. Among the various H2 production routes, photocatalytic water splitting has received particular interest; it strongly relies on the optical and structural properties of photocatalysts such as their sunlight absorption capabilities, carrier transport properties, and amount of oxygen vacancy. Perovskite oxides have been widely investigated as photocatalysts for photocatalytic water splitting to produce H2 because of their distinct optical properties, tunable band gaps and excellent compositional/structural flexibility. Herein, an aluminum cation (Al3+) doping strategy is developed to enhance the photocatalytic performance of Ruddlesden-Popper (RP) Sr2TiO4 perovskite oxides for photocatalytic H2 production. After optimizing the Al3+ substitution concentration, Sr2Ti0.9Al0.1O4 exhibits a superior H2 evolution rate of 331 μmol h−1 g−1, which is ~3 times better than that of Sr2TiO4 under full-range light illumination, due to its enhanced light harvesting capabilities, facilitated charge transfer, and tailored band structure. This work presents a simple and useful Al3+ cation doping strategy to boost the photocatalytic performance of RP-phase perovskites for solar water splitting.

Self-snapping hydrogel-based electroactive microchannels as nerve guidance conduits

Peripheral nerve regeneration with large defects needs innovative design of nerve guidance conduits (NGCs) which possess anisotropic guidance, electrical induction and right mechanical properties in one. Herein, we present, for the first time, facile fabrication and efficient neural differentiation guidance of anisotropic, conductive, self-snapping, hydrogel-based NGCs. The hydrogels were fabricated via crosslinking of graphitic carbon nitride (g-C₃N₄) upon exposure with blue light, incorporated with graphene oxide (GO). Incorporation of GO and in situ reduction greatly enhanced surface charges, while decayed light penetration endowed the hydrogel with an intriguing self-snapping feature by the virtue of a crosslinking gradient. The hydrogels were in the optimal mechanical stiffness range for peripheral nerve regeneration and supported normal viability and proliferation of neural cells. The PC12 ​cells differentiated on the electroactive g-C₃N₄ H/rGO3 (3 ​mg/mL GO loading) hydrogel presented 47% longer neurite length than that of the pristine g-C₃N₄ H hydrogel. Furthermore, the NGC with aligned microchannels was successfully fabricated using sacrificial melt electrowriting (MEW) moulding, the anisotropic microchannels of the 10 ​μm width showed optimal neurite guidance. Such anisotropic, electroactive, self-snapping NGCs may possess great potential for repairing peripheral nerve injuries.

Pickering emulsions as an alternative to traditional polymers: trends and applications

Pickering emulsions have gained increasing interest because of their unique features, including easy preparation and stability. In contrast to classical emulsions, in Pickering emulsions, the stabilisers are solid micro/nanoparticles that accumulate on the surfaces of liquid phases. In addition to their stability, Pickering emulsions are less toxic and responsive to external stimuli, which make them versatile material that can be flexibly designed for specific applications, e.g., catalysis, pharmaceuticals and new materials. The potential toxicity and adverse impact on the environment of classic emulsions is related to the extractable nature of the water emulsifier. The impacts of some emulsifiers are related to not only their chemical natures but also their stabilities; after base or acid hydrolysis, some emulsifiers can be turned into sulphates and fatty alcohols, which are dangerous to aquatic life. In this paper, recent research on Pickering emulsion preparations is reviewed, with a focus on styrene as one of the main emulsion components. Moreover, the effects of the particle type and morphology and the critical parameters of the emulsion production process on emulsion properties and applications are discussed. Furthermore, the current and prospective applications of Pickering emulsion, such as in lithium-ion batteries and new vaccines, are presented.

Microgels based on 0D-3D carbon materials: Synthetic techniques, properties, applications, and challenges

Microgels are three-dimensional (3D) colloidal hydrogel particles with outstanding features such as biocompatibility, good mechanical properties, tunable sizes from submicrometer to tens of nanometers, and large surface areas. Because of these unique qualities, microgels have been widely used in various applications. Carbon-based materials (CMs) with various dimensions (0-3D) have recently been investigated as promising candidates for the design and fabrication of microgels because of their large surface area, excellent conductivity, unique chemical stability, and low cost. Here, we provide a critical review of the specific characteristics of CMs that are being incorporated into microgels, as well as the state-of-the art applications of CM-microgels in pollutant adsorption and photodegradation, H₂ evoluation, CO₂ capture, soil conditioners, water retention, drug delivery, cell encapsulation, and tissue engineering. Advanced preparation techniques for CM-microgel systems are also summarized and discussed. Finally, challenges related to the low colloidal stability of CM-microgels and development strategies are examined. This review shows that CM-microgels have the potential to be widely used in various practical applications.

Facile synthesis of mesoporous polymeric carbon nitride nanosheets anchored by Pt with ultralow loading for high-efficiency photocatalytic H2 evolution

The facile fabrication of low-cost photocatalysts with enhanced activity and high atomic utilization is becoming increasingly necessary for solar energy usage and/or conversion. In this work, a series of mesoporous carbon nitride nanosheets with an enlarged specific surface area was synthesized via an inorganic acid-assisted exfoliation method without any soft or hard templates. An ultralow loading of downsized noble metal Pt was anchored on these porous nanosheets, exhibiting enhanced photocatalytic activity. The formation of mesoporous nanosheets in carbon nitride was expected to boost the mass transfer and shorten the charge carrier transfer route during the photocatalytic reaction. The characterization of samples revealed that the enhanced conductivity and photocurrent of the carbon nitride nanosheets also contributed to the enhanced H₂ evolution activity. The maximum H₂ production rates of 172.92 μmol h^-1 and 321 μmol h^-1 were achieved over the nanosheets derived from melamine and urea under visible light irradiation, which are 10.92- and 2.22-fold that of the corresponding bulk carbon nitride, respectively. This exfoliation method was demonstrated to be an efficient and universal method for the preparation of carbon nitride nanosheets with a mesoporous structure and high atom utilization of the co-catalyst for H₂ evolution from water.

Self-floating photocatalytic hydrogel for efficient removal of Microcystis aeruginosa and degradation of microcystins-LR

Cyanobacterial harmful algal blooms (CyanoHABs) and the release of cyanotoxins have posed adverse impacts to aquatic system and human health. In this study, a novel self-floating Ag/AgCl@LaFeO₃ (ALFO) photocatalytic hydrogel was prepared via freeze-thaw method for removal of Microcystis aeruginosa (M. aeruginosa). The ALFO hydrogel performed an excellent photocatalytic activity with a 99.4% removal efficiency of chlorophyll a within 4 h. It can still remove above 95% chlorophyll a after six consecutive recycles. Besides it has also shown excellent mechanical strength and elasticity, which can ensure its use in practical applications. The mechanisms of M. aeruginosa inactivation are attributed to •O₂^- and •OH generated by the ALFO hydrogel under visible light radiation. In addition, •O₂^- and •OH can further oxidative degrade and even mineralize the leaked algae organic matter, avoiding the recurrence of CyanoHABs. What's more, the ALFO hydrogel owns good photocatalytic degradation performance for microcystins-LR (MC-LR) with a 97% removal efficiency within 90 min. A possible photocatalytic degradation pathway of MC-LR was proposed through the identification of the intermediate products during the photocatalytic reaction, which confirmed the reduction of MC-LR toxicity. This work develops recyclable a self-floating ALFO hydrogel to simultaneously inactivate M. aeruginosa and degrade MC-LR, providing a prospective method for governing and controlling CyanoHABs in practical application.

Semiconducting graphitic carbon nitride integrated membranes for sustainable production of clean water: A review

Semiconducting membranes integrated with nanomaterials have placed themselves in new emerging researches tremendously for seawater desalination, oil-water separation, disinfection, removal of inorganic as well as organic pollutants. Howbeit, only nanoparticles unified membranes show quite a lot lags in their performance, although some of these particles associated with the demerits of high cost. In contrast, graphitic carbon nitride incorporated membranes offered improved aforementioned properties corresponding to absolute essential qualities such as cost-effective, environmentally friendly, easy-to-operate, green manufacturing, anti-fouling, and low energy consumption. Moreover, their high mechanical strength, high stability against harsh environment and long-term utilization without flux reduction are strong plus. Even though there are some undeniable downsides of these membranes in real world applications as bulk synthesis, consistent dispersion of graphitic carbon nitride, low photocatalytic efficiency etc. Accordingly, in the present article, these frailties of the membranes having graphitic carbon nitride as a filler and their respective synthesis procedures and properties are discussed. A comprehensive analysis over the application of semiconducting graphitic carbon nitride incorporated membranes with and without special surface modification; and exploration of the future challenges and difficulties associated to these membranes are also reviewed. Consequently, the current article provides brief overview about graphitic carbon nitride integrated composite membranes as well as their applications, and it finished up with new thoughts of further improvements/modifications to overcome their shortcomings in actual environmental conditions.

Influence of Ag nanoparticles anchored on protonated g-C3N4-Bi2MoO6 nanocomposites for effective antibiotic and organic pollutant degradation

The development of noble metal-anchored semiconductors for photocatalytic processes is now garnering interest for potential application to toxic pollutants as well as antibiotic degradation. Herein, we report novel Ag@p-g-C₃N₄-Bi₂MoO₆ nanocomposites synthesized by facile hydrothermal and calcination methods with a size of about 50 nm, exhibiting superior photocatalytic activity for charge separation. The resulting nanocomposites were evaluated by various physiochemical techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The charge transfer photogenerated carriers were confirmed by photoluminescence spectra and electrochemical impedance spectroscopy. The anchoring of Ag nanoparticles over p-g-C₃N₄/Bi₂MoO₆ decreased the band gap energy from 2.67 to 2.48 eV, to exhibit an abnormal increase in absorption of light towards the visible light region. The degradation performance of the nanocomposites in terms of antibiotic ciprofloxacin and rhodamine B degradation efficiency was measured 85 and 99.7% respectively. The superoxide radical anion ˙O₂ ^- played a significant role throughout the entire degradation process. Focusing on the probable mechanism based on the desirable results, the present work follows the heterostructure mechanism. Moreover, this work features the feasible applications of Ag@p-g-C₃N₄-Bi₂MoO₆ as a modified photocatalyst in the treatment of both domestic and industrial waste water.

Influence of Phosphorus Doping on Triazole-Based g-C3N5 Nanosheets for Enhanced Photoelectrochemical and Photocatalytic Performance

Triazole-based g-C₃N₅, a potential catalyst, has received little attention over the years. We prepared phosphorus-doped g-C₃N₅ with one triazole and two triazine units for the first time to investigate its photoelectrochemical (PEC) and photocatalytic properties. The doping states and crystalline structures of the samples were determined using X-ray techniques, namely, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption fine structure analysis. Our results suggested that the phosphorus was substituted into carbon sites form P-N/P═N bonds with four coordination, which contribute P 2p level donor states in the band gap to enhance light absorption and reduce charge separation. Therefore, P-doped g-C₃N₅ exhibited higher PEC current density and better photocatalytic efficiency toward the degradation of rhodamine B dye or tetracycline under light irradiation compared to the undoped g-C₃N₅ sample. However, excess phosphorus doping resulted in the formation of impurities and disrupted the triazine and triazole units, reducing the PEC and photocatalytic efficiency. In summary, P-doped g-C₃N₅ was successfully prepared in the present study and represents a promising, facile, and effective catalyst for energy applications and environmental remediation.

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

Hydrogels are a special class of crosslinked hydrophilic polymers with a high water content through their porous structures. Post-modifications of hydrogels propose an attractive platform so that a variety of fresh functions, which are not arising from initial monomers, could be accessible on a parental network. Photoinduced post-modification of hydrogels by embedding semiconductor nanosheets would be of high interest and novelty. Here, a metal-free semiconductor graphitic carbon nitride (g-CN)-embedded hydrogel as an initial network was synthesized via redox-couple initiation under dark conditions. Post-photomodification of so-formed hydrogel, thanks to the photoactivity of the embedded g-CN nanosheets, was exemplified in two scenarios. The synthesis of 'hydrophobic hydrogel' is reported and its application in delayed cation delivery was investigated. Furthermore, pores of the initial hydrogel were modified by the formation of a secondary polymer network. Such a facile and straightforward synthetic protocol to manufacture functional soft materials will be of high interest in near future by the means of catalysis and agricultural delivery.

Injectable hydrogels based on oxidized alginate-gelatin reinforced by carbon nitride quantum dots for tissue engineering

Stem cell treatment is promising in the various disorders treatment, but its effect is confined by the adverse conditions in the damaged tissues. The utilization of hydrogels has been suggested as a procedure to defeat this issue by developing the engraftment and survival of injected stem cells. Specifically, injectable hydrogels have drawn much attention due to their shape adaptability, ease of use, and the capability to reach body parts that are hard to access. In this study, the thermosensitive injectable hydrogels based on oxidized alginate, gelatin, and carbon nitride quantum dots (CNQDs) have been fabricated for tissue engineering. The mechanical characteristics of the nanocomposite hydrogels were investigated by rheology analysis. The results show that increasing the amount of CNQDs improve the mechanical strength of the nanocomposite hydrogels. The Cross-section morphology of freeze dried hydrogels comprising 0.25, 1.5, and 3.0% CNQDs indicate porous structure with interrelated pores. Besides, the result of in vitro degradation reveals that the hydrogels comprising CNQDs are more durable than the one without CNQDs. A reduction in the biodegradation and swelling ratio is perceived with the addition of CNQDs. The cell viability and attachment show that the nanocomposite hydrogels are biocompatible (>88%) with great cell adhesion to osteosarcoma cell line MG63 depending on the presence of CNQDs.

Molding and Encoding Carbon Nitride-Containing Edible Oil Liquid Objects via Interfacial Toughening in Waterborne Systems

Charge interaction-driven jamming of nanoparticle monolayers at the oil-water interface can be employed as a method to mold liquids into tailored stable 3D liquid objects. Here, 3D liquid objects are fabricated via a combination of biocompatible aqueous poly(vinyl sulfonic acid, sodium salt) solution and a colloidal dispersion of highly fluorescent organo-modified graphitic carbon nitride (g-C₃N₄) in edible sunflower oil. The as-formed liquid object shows stability in a broad pH range, as well as flexible pathways for efficient exchange of molecules at the liquid-liquid interphase, which allows for photodegradation of rhodamine B at the interface via visible light irradiation that also enables an encoding concept. The g-C₃N₄-based liquid objects point toward various applications, for example, all-liquid biphasic photocatalysis, artificial compartmentalized systems, liquid-liquid printing, or bioprinting.

3D printed photoreactor with immobilized graphitic carbon nitride: A sustainable platform for solar water purification

Solar-energy-enabled photocatalysis is promising for sustainable water purification. However, photoreactor design, especially immobilizing nano-sized photocatalysts, remains a major barrier preventing industrial-scale application of photocatalysis. In this study, we immobilized photocatalytic graphitic carbon nitride on chitosan to produce g-C₃N₄/chitosan hydrogel beads (GCHBs), and evaluated GCHB photoreactivity for degrading phenol and emerging persistent micropollutants in a 3D printed compound parabolic collector (CPC) reactor. The CPC photocatalytic system showed comparable performance with slurry reactors for sulfamethoxazole and carbamazepine degradation under simulated sunlight, and it maintained the performance for contaminant removal in real water samples collected from water/wastewater treatment plants or under outdoor sunlight irradiation. Global drinking water production was estimated for the CPC system, and it holds promise for small-scale sustainable water treatment, including, but not limited to, the production of high-quality potable water for single houses, small communities, rural areas, and areas impacted by natural disasters in both developed and developing countries.

Facile Synthesis of Lacunary Keggin-Type Phosphotungstates-Decorated g-C3N4 Nanosheets for Enhancing Photocatalytic H2 Generation

In this work, the lacunary Keggin-type phosphotungstates of [PW9O34]9- (PW9) clusters were loaded onto the g-C3N4 nanosheets (NSs) to synthesize the phosphotungstate clusters-decorated 2D heterojunction photocatalysts by using the electrostatic-force driven self-assembly process. The surface charge polarity of g-C3N4 NSs was changed from a negative to a positive charge through the acidizing treatment. The positively-charged g-C3N4 NSs allowed the negatively-charged PW9 clusters to be adsorbed and deposited onto the g-C3N4 NSs, forming the PW9/g-C3N4 heterojunction NSs. The as-synthesized samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and UV-VIS absorption spectra, respectively. The photocatalytic activity tests indicated that, upon simulated sunlight irradiation, the photocatalytic H2-generation rate of PW9/g-C3N4 heterojunction NSs (~23.8 μmol h-1) was ~3.3 times higher than that of the pure g-C3N4 NSs (~7.3 μmol h-1). The enhanced photocatalytic activity of PW9 cluster-decorated g-C3N4 NSs could be attributed to the enhanced separation process of the photoinduced charge-carriers, due to the Z-scheme-mediate charge transfer behavior across their hetero-interface.

Graphitic Carbon Nitride Stabilizers Meet Microfluidics: From Stable Emulsions to Photoinduced Synthesis of Hollow Polymer Spheres

Graphitic carbon nitride (g-CN) has been utilized as a heterogeneous catalyst, but is usually not very well dispersible. The amphiphilic character of g-CN can be altered by surface modifications of g-CN nanopowders. Introducing hydrophilicity or hydrophobicity is a promising avenue for producing advanced emulsion systems. In this study, a special surface-modified g-CN is used to form stable Pickering emulsions. Using a PDMS-based microfluidic device designed for stable production of both single and double emulsions, it is shown that surface-modified g-CNs allow the manufacture of unconventionally stable and precise Pickering emulsions. Shell thickness of the double emulsions is varied to emphasize the robustness of the device and also to demonstrate the extraordinary stabilization brought by the surface-modified carbon nitride used in this study. Due to the electrostatic stabilization also in the oil phase, double emulsions are centered. Finally, when produced from polymerizable styrene, hollow polymer microparticles are formed with precise and tunable sizes, where g-CN is utilized as the only stabilizer and photoinitiator.

Smartdust 3D-Printed Graphene-Based Al/Ga Robots for Photocatalytic Degradation of Explosives

Milli/micro/nanorobots are considered smart devices able to convert energy taken from different sources into mechanical movement and accomplish the appointed tasks. Future advances and realization of these tiny devices are mostly limited by the narrow window of material choices, the fuel requirement, multistep surface functionalization, rational structural design, and propulsion ability in complex environments. All these aspects call for intensive improvements that may speed up the real application of such miniaturized robots. 3D-printed graphene-based smartdust robots provided with a magnetic response and filled with aluminum/gallium molten alloy (Al/Ga) for autonomous motion are presented. These robots can swim by reacting with the surrounding environment without adding any fuel. Because their outer surface is coated with a hydrogel/photocatalyst (chitosan/carbon nitride, C₃ N₄ ) layer, these robots are used for the photocatalytic degradation of the picric acid as an explosive model molecule under visible light. The results show a fast and efficient degradation of picric acid that is attributed to a synergistic effect between the adsorption capability of the chitosan and the photocatalytic activity of C₃ N₄ particles. This work provides added insight into the large-scale fabrication, easy functionalization, and propulsion of tiny robots for environmental applications.

Influence of Photocatalysis on Blood Cell Attachment over Protein-Immobilized Polystyrene Surfaces Modified with a Poly(styrene)-b-Poly(acrylic acid) Copolymer

In the present study, thrombocytes, erythrocytes, and leukocytes were individually brought into contact with different immobilized blood proteins on the surface of polystyrene (PS), which was modified with a poly(styrene)-b-poly(acrylic acid) copolymer. When the concentration of fibronectin was greater than 5 μg mL^-1, the attachment of erythrocytes increased, which indicated that the modified PS surface was less compatible with erythrocytes. In addition, vitronectin and laminin attached on the surface increased the adhesion of thrombocytes; higher adhesion was observed for leukocytes in the cases of fibrinogen, lysozyme, and laminin. Interestingly, adhesion properties of blood cells on the protein surface could be influenced by the addition of metal oxide- and carbon-based photocatalysts. After a photocatalytic treatment by metal oxide-based TiO₂, the adhesion amounts of erythrocytes improved slightly, whereas the adhesion of leukocytes and thrombocytes decreased after treatment with a carbon-based g-C₃N₄ nanosheet. Our results suggested that the surface modification of the substrate through photocatalysis using various photocatalysts along with the grafting of the poly(styrene)-b-poly(acrylic acid) copolymer could be a promising approach to alternatively control the blood compatibility on the protein surface.

Development of BiOI as an effective photocatalyst for oxygen evolution reaction under simulated solar irradiation

In this study, crystalline BiOI powders were prepared for photocatalytic O₂ evolution in the presence of NaIO₃ as the electron mediator.

Novel La(OH)3-integrated sGO-Ag3VO4/Ag nanocomposite as a heterogeneous photocatalyst for fast degradation of agricultural and industrial pollutants

The composite described couples the benefits of hydroxyl radical formation from sunlight-inactive La(OH)₃ and strong sunlight absorption by Ag₃VO₄.

Synergistic Effect of Hydrochloric Acid and Phytic Acid Doping on Polyaniline-Coupled g-C3N4 Nanosheets for Photocatalytic Cr(VI) Reduction and Dye Degradation

In this study, graphitic carbon nitride (g-C₃N₄) nanosheets (CNns) were modified using polyaniline (PANI) codoped with an inorganic (hydrochloric acid, HCl) and an organic (phytic acid, PA) acid. Our results revealed that these samples exhibited extended visible-light absorption and a three-dimensional (3D) hierarchical structure with a large specific surface area. They also inhibited photoluminescence emission, reduced electrical resistance, and provided abundant free radicals, resulting in high photocatalytic performance. The PANI/g-C₃N₄ sample demonstrated outstanding photocatalytic activity of a Cr(VI) removal capacity of 4.76 mg·min^-1·g_c^-1, which is the best record for the reduction of a 100 ppm K₂Cr₂O₇ solution. Moreover, g-C₃N₄ coupled with PANI monotonically doped with HCl or PA did not demonstrate increased activity, suggesting that the codoping of HCl and PA plays a significant role in enhancing the performance. The improved photocatalytic activity of PANI/g-C₃N₄ can be attributed to the interchain and intrachain doping of PA and HCl over PANI, respectively, to create a 3D connected network and synergistically increase the electrical conductivity. Therefore, new insights into g-C₃N₄ coupled with PANI and codoped by HCl and PA may have excellent potential for the design of g-C₃N₄-based compounds for efficient photocatalytic reactions.

Photocatalytic Dye and Cr(VI) Degradation Using a Metal-Free Polymeric g-C₃N₄ Synthesized from Solvent-Treated Urea

The development of visible-light-driven polymeric g-C₃N₄ is in response to an emerging demand for the photocatalytic dye degradation and reduction of hexavalent chromium ions. We report the synthesis of g-C₃N₄ from urea treated with various solvents such as methanol, ethanol, and ethylene glycol. The samples were characterized and the Williamson⁻Hall method was applied to investigate the lattice strain of the samples. The activity of the samples was evaluated by observing the degradation of methyl orange and K₂Cr₂O₇ solution under light irradiation. Photocatalytic reaction kinetics were determined as pseudo-first-order and zero-order for the degradation of methyl orange and reduction of hexavalent chromium, respectively. Due to the inhibited charge separation resulting from the small lattice strain, reduced crystal imperfection, and sheet-like structure, g-C₃N₄ obtained from ethanol-treated urea exhibited the highest activity among the evaluated samples.

Heterostructural design of I-deficient BiOI for photocatalytic decoloration and catalytic CO2 conversion

I⁻ vacancies in BiOI play a major role in governing the photocatalysis and catalysis.

Polymer grafted graphitic carbon nitrides as precursors for reinforced lubricant hydrogels

Carbon nitride-based hydrogels are formed in a two-step procedure and feature significant toughness, compressibility and lubricant properties.

MOF-templated in situ fabrication of surface-modified Ni/graphitic carbon nitride with enhanced photocatalytic hydrogen evolution

Surface-modified Ni species derived from 2D Ni-MOFs were loaded on g-C₃N₄ with high dispersion by the in situ calcination method.