Ultrathin Graphitic Carbon Nitride Nanosheets Research Articles

Oxygen-doped Porous Ultrathin Graphitic Carbon Nitride Nanosheets for Photocatalytic Hydrogen Evolution and Rhodamine B Degradation.

Graphite phase carbon nitride (g-C3N4) is a highly promising metal-free photocatalyst. However, its applicability is restricted by low activity, due to weak quantum efficiency and small specific surface area. Exfoliating bulk crystals into porous thin-layer nanosheets and introducing element doping have been shown to improve photocatalytic efficiency, but these methods are often complex, time-consuming, and costly processes. In this study, we successfully synthesized porous oxygen-doped g-C3N4 (OCN) nanosheets utilizing a straightforward method. Our findings show that OCN have much higher light absorption and visible-light photocatalytic activity than bulk g-C3N4 (BCN) and nonporous g-C3N4 (CN). The OCN photocatalyst has a remarkable hydrogen evolution reaction (HER) rate of 8.02 mmol·g-1 h-1, which is 8 times greater than BCN. Additionally, the OCN shows a high degradation rate of 97.3% for Rhodamine B (RhB). This enhanced photocatalytic activity is ascribed to the narrow band gap and superior electron transfer capacity. Our findings suggest a potential technique for generating efficient g-C3N4 photocatalysts.

Enhanced Photobiocatalytic Cascades at Pickering Droplet Interfaces.

Developing new methods to engineer photobiocatalytic reactions is of utmost significance for artificial photosynthesis, but it remains a grand challenge due to the intrinsic incompatibility of biocatalysts with photocatalysts. In this work, photocatalysts and enzymes were spatially colocalized at Pickering droplet interfaces, where the reaction microenvironment and the spatial distance between two distinct catalysts were exquisitely regulated to achieve unprecedented photobiocatalytic cascade reactions. As proof of the concept, ultrathin graphitic carbon nitride nanosheets loaded with Au nanoparticles were precisely positioned in the outer interfacial layer of Pickering oil droplets to produce H2O2 under light irradiation, while enzymes were exactly placed in the inner interfacial layer to catalyze the subsequent biocatalytic oxidation reactions using in situ formed H2O2 as an oxidant. In the alkene epoxidation and thioether oxidation, our interfacial photobiocatalytic cascades showed a 2.0-5.8-fold higher overall reaction efficiency than the photobiocatalytic cascades in the bulk water phase. It was demonstrated that spatial localization of the photocatalyst and the enzyme at Pickering oil droplet interfaces not only provided their respective preferable reaction environments and intimate proximity for rapid H2O2 transport but also protected the enzyme from oxidative inactivation caused by the photogenerated species. These remarkable interfacial effects contributed to the significantly enhanced photobiocatalytic cascading efficiency. Our work presents an innovative photobiocatalytic reaction system with manifold benefits, providing a cutting-edge platform for solar-driven chemical transformations via photobiocatalysis.

Electron-enriched single-Pd-sites on g-C3N4 nanosheets achieved by in-situ anchoring twinned Pd nanoparticles for efficient CO2 photoreduction

Modulating electronic structures of single-atom metal cocatalysts is vital for highly active photoreduction of CO2, and it's especially challenging to develop a facile method to modify the dispersion of atomical photocatalytic sites. We herein report an ion-loading pyrolysis route to in-situ anchor Pd single atoms as well as twinned Pd nanoparticles on ultra-thin graphitic carbon nitride nanosheets (PdTP/PdSA-CN) for high-efficiency photoreduction of CO2. The anchored Pd twinned nanoparticles donate electrons to adjacent single Pd–N4 sites through the carbon nitride networks, and the optimized PdTP/PdSA-CN photocatalyst exhibits a CO evolution rate up to 46.5 ​μmol ​g−1 ​h−1 with nearly 100% selectivity. As revealed by spectroscopic and theoretical analyses, the superior photocatalytic activity is attributed to the lowered desorption barrier of carbonyl species at electron-enriched Pd single atoms, together with the improved efficiencies of light-harvesting and charge separation/transport. This work has demonstrated the engineering of the electron density of single active sites with twinned metal nanoparticles assisted by strong electronic interaction with the support of the atomic metal, and unveiled the underlying mechanism for expedited photocatalytic efficiency.

Exploring the Remarkably High Photocatalytic Efficiency of Ultra-Thin Porous Graphitic Carbon Nitride Nanosheets.

Graphitic carbon nitride (g-C3N4) is a metal-free photocatalyst used for visible-driven hydrogen production, CO2 reduction, and organic pollutant degradation. In addition to the most attractive feature of visible photoactivity, its other benefits include thermal and photochemical stability, cost-effectiveness, and simple and easy-scale-up synthesis. However, its performance is still limited due to its low absorption at longer wavelengths in the visible range, and high charge recombination. In addition, the exfoliated nanosheets easily aggregate, causing the reduction in specific surface area, and thus its photoactivity. Herein, we propose the use of ultra-thin porous g-C3N4 nanosheets to overcome these limitations and improve its photocatalytic performance. Through the optimization of a novel multi-step synthetic protocol, based on an initial thermal treatment, the use of nitric acid (HNO3), and an ultrasonication step, we were able to obtain very thin and well-tuned material that yielded exceptional photodegradation performance of methyl orange (MO) under visible light irradiation, without the need for any co-catalyst. About 96% of MO was degraded in as short as 30 min, achieving a normalized apparent reaction rate constant (k) of 1.1 × 10-2 min-1mg-1. This represents the highest k value ever reported using C3N4-based photocatalysts for MO degradation, based on our thorough literature search. Ultrasonication in acid not only prevents agglomeration of g-C3N4 nanosheets but also tunes pore size distribution and plays a key role in this achievement. We also studied their performance in a photocatalytic hydrogen evolution reaction (HER), achieving a production of 1842 µmol h-1 g-1. Through a profound analysis of all the samples' structure, morphology, and optical properties, we provide physical insight into the improved performance of our optimized porous g-C3N4 sample for both photocatalytic reactions. This research may serve as a guide for improving the photocatalytic activity of porous two-dimensional (2D) semiconductors under visible light irradiation.

Structural engineering and nitrogen doping of graphitic carbon nitride for photocatalytic degradation of organic pollutants under visible light

The ultrathin and porous graphitic carbon nitride (g-C3N4) nanosheets with structural design and abundant nitrogen dopants were synthesized via a one-step calcination procedure. The exfoliated and doped g-C3N4 (NT-CN) displayed enhanced photocatalytic activity for degradation of hydrochloride tetracycline and rhodamine B degradation in the complex water matrixes with different pH values or even in the presence of various anions (Cl−, CO2–3, NO- 3, and SO2–4). N-doped porous structure provided an extremely high surface area and enhanced basicity, enabling NT-CN catalyst to adsorb the abundant active species and pollutants. Moreover, NT-CN exhibited a wide band gap with a strong negative CB minimum of −1.07 eV that facilitated the formation of more photoexcited electrons. During the reaction process, the generated electrons reacted with dissolved O2 to produce the ·O2− species, and then transformed into highly reactive and stable 1O2 species, which play a predominant role in eliminating pollutants.

Synergistic enhancement of photocatalytic hydrogen evolution by ultrathin oxygen-doped graphitic carbon nitride nanosheets loaded amorphous mesoporous nickel hydroxide

Graphitic carbon nitride (g-C3N4, CN) is widely utilized in the field of photocatalytic hydrogen production owing to its exceptional visible light absorption, addressing the challenge of energy scarcity. However, its development has been hindered by the issue of low charge separation efficiency. In this study, an ultrathin (∼1.65 nm) oxygen-doped graphitic carbon nitride nanosheets loaded amorphous mesoporous nickel hydroxide (a-Ni(OH)2/OCN) photocatalyst was developed through a straightforward calcination and stirring approach. Under visible light irradiation, a-Ni(OH)2/OCN exhibited a remarkably high photocatalytic hydrogen evolution rate of 4764.9 μmol·h−1 g−1, which is 4.7 times greater than that of the original CN. The synergistic effect between O-doping and heterojunction was proved by experimental data analysis combined with DFT calculations. Totally, the introduction of oxygen into CN led to a reduction in its band gap, while a-Ni(OH)2/OCN heterojunction achieved a broaden light absorption range and an effective charge separation due to a type-Ⅱ internal electric fields.

Synergistic effect of n-π* electronic transitions in porous ultrathin graphitic carbon nitride nanosheets for efficient photocatalytic hydrogen production

The visible light absorption capacity and active sites of graphitic carbon nitride (GCN) are crucial roles for photocatalytic hydrogen (H2) production. However, the fabrication of ultrathin GCN nanosheets with enhanced light absorption via n-π* electronic transitions remain challenging. Here, we report on the successful preparation of porous ultrathin GCN nanosheets with activating n-π* electronic transitions simultaneously by microwave heating the mixture of urea and ammonium chloride (NH4Cl) compression strategy. Such the unique structure of GCN is composed of a curved porous thin layer and has numerous wrinkles that not only largely expand visible light absorption range to ∼ 650 nm but also significantly enhance the unmber of active sites and the mobility of photoexcited charges. The highest photocatalytic H2 production rate reached 99.1 μmol h−1 under visible light irradiation (λ > 420 nm), which is 8.8 folds higher than that of pristine GCN (11.2 μmol h−1). This work presents a promising and effective strategy for the engineering of GCN, which fully utilizes n-π* electronic transitions to largely expand the visible light absorption while enhancing the active sites.

Ultrathin graphitic carbon nitride (g-C3N4) nanosheets: Synthesis, properties, and photocatalytic application

In recent years graphitic carbon nitride (g-C3N4) has been considered the most popular candidate for replacing graphene and other similar materials in various applications. The g-C3N4 has unique electronic and mechanical properties, huge photoluminescence in the wide optical region, and promising properties in energy conversion and storage, water splitting, etc. Here we show a simple method of bulk g-C3N4 (BCN) synthesis using thermal polymerization of melamine and ultrathin 2D g-C3N4 nanosheets (NCN) prepared by ultrasonic exfoliation of BCN in water. The g-C3N4 samples were tested with XRD, FTIR, Raman, luminescence spectroscopy, and N2 adsorption at 77 K. We characterize its photocatalytic properties in H2 evolution by direct water splitting. We utilize the low-cost 10 W white LEDs photoreactor with visible light and flow conditions. In the water-splitting reaction, we found that the NCN were about 5 times more reactive than the primary BCN sample.

Photoinduced Electron Transfer-Triggered g-C3N4\Rhodamine B Sensing System for the Ratiometric Fluorescence Quantitation of Carbendazim.

Assays for carbendazim (Car) with high sensitivity and on-site screening have been urgently required to protect the ecosystem and prevent disease. In this work, a simple, sensitive, and reliable sensing system based on photoinduced electron transfer was established to detect carbendazim utilizing ultrathin graphitic carbon nitride (g-C3N4) nanosheets and rhodamine B (RB). Carbendazim reacts with g-C3N4 by electrostatic interactions to form π-π stacking, and the quenching of the blue fluorescence is caused by electron transfer. While RB works as a reference fluorescence sensor without any fluorescence change, leading to obvious ratiometric fluorescence variation from blue to purple. Under optimal conditions, a favorable linear range from 20 to 180 nM was obtained, with a low detection limit of 5.89 nM. In addition, a portable smartphone sensing platform was successfully used for carbendazim detection in real samples with excellent anti-interference capability, demonstrating the potential applications of carbendazim monitoring.

Composite polymer electrolyte reinforced by graphitic carbon nitride nanosheets for room-temperature all-solid-state lithium batteries

By virtue of the flexibility and safety, polyethylene oxide (PEO) based electrolytes are regarded as an appealing candidate for all-solid-state lithium batteries. However, their application is limited by the poor ionic conductivity at room temperature, narrow electrochemical stability window and uncontrolled growth of lithium dendrite. To alleviate these problems, we introduce the ultrathin graphitic carbon nitride nanosheets (GCN) as advanced nanofillers into PEO based electrolytes (GCN-CPE). Benefiting from the high surface area and abundant surface N-active sites of GCN, the GCN-CPE displays decreased crystallinity and enhanced ionic conductivity. Meanwhile, Fourier transform infrared (FTIR) and chronoamperometry studies indicate that GCN can facilitate Li + migration in the composite electrolyte. Additionally, the GCN-CPE displays an extended electrochemical window compared with PEO based electrolytes. As a result, Li symmetric battery assembled with GCN-CPE shows a stable Li plating/stripping cycling performance, and the all-solid-state Li/LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) batteries using GCN-CPE exhibit satisfactory cyclability and rate capability in a voltage range of 3−4.2 V at 30 °C.

Fabrication of CoFe2O4/Mn3O4 decorated ultrathin graphitic carbon nitride nanosheets membrane for persistent organic pollutants removal: Synergistic performance and mechanisms

Integration of sulfate radicals-based advanced oxidation processes (SR-AOPs) with separation membranes has enthralled considerable attentions because it can remove persistent toxic micropollutants in a low-energy and cost-effective manner. However, fabrication of such an integrated membrane simultaneously with excellent self-cleaning property, catalytic capability and long-term durability remains a challenge. Herein, for the first time, CoFe2O4 (CFO) and Mn3O4 (MO) nanoparticles were anchored on ultrathin graphitic carbon nitride (UCN) nanosheets via a solvothermal method to prepare heterogeneous Fenton-like catalysts (MO/CFOUCN). Systematic characterizations demonstrated the successful preparation of powder catalysts with favorable degradation ability. Notably, the optimal composite catalyst possessed satisfactory degradation (94.5 %) and kinetic rate (0.1367 min−1) for norfloxacin (NOR) within 30 min. Thereafter, an integrated MO/CFO/UCN@P membrane was fabricated by vacuum-assisted filtration of the catalyst on a supporting membrane surface. It was interestingly found that, benefiting from the synergistic effect of in-situ oxidation and membrane filtration, activating peroxymonosulfate (PMS) endowed the membrane with high removal rates (over 91.8 % for tetracycline, bisphenol A, humic acid (HA)) and high permeation flux (332.7 L·m−2·h−1) driven solely by gravity. Significantly, the membrane achieved a flux recovery rate of 91.9 % with the assistance of PMS after filtering HA solution. Furthermore, quenching experiments and electron paramagnetic resonance (EPR) tests confirmed that both radical and nonradical pathways contributed to the mineralization of NOR. Based on the detection of intermediates in the degradation process, potential NOR degradation pathways were proposed. Overall, this study provided new ideas about integrating Fenton-like catalysts with membrane technology for removal of persistent organic pollutants.

Designing ultrathin Ag-embedded g-C3N4 nanocomposites for enhanced disinfection performance under visible light

Using ammonium chloride (NH4Cl) as a gas template, we conveniently fabricated ultrathin two-dimensional layered silver-embedded graphitic carbon nitride nanosheets (AgCNS) by melamine blowing method with triazine groups of pristine graphite carbon nitride. Compared with bulk g-C3N4 (BCN) and g-C3N4 nanosheets (CNS), the antibacterial activity of the optimized AgCNS-5 at a minimum inhibitory concentration (MIC) of 40 ppm against Escherichia coli (E. coli) was significantly enhanced. Under visible-light irradiation, E. coli could be completely killed by 100 µg·mL−1 of AgCNS-5 within 30 min. The mechanism of enhanced antibacterial activity was systematically investigated by ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), photoluminescence spectra (PL), electrochemical impedance spectroscopy (EIS), and photogenerated current densities. Surface plasmonic resonance (SPR) of Ag nanoparticles (NPs) with g-C3N4 was found to lead to an enhancement of visible light absorption and an acceleration of photo-induced electron-hole migration/separation, which is responsible for the enhanced photocatalytic bactericidal performance. Through trapping experiments and electron spin resonance spectroscopy (ESR) techniques, the bactericidal mechanism was revealed that the species of •O2− and •OH play important roles in antibacterial process. Considering the facile preparation and excellent performance, AgCNS-5 may be a promising and competitive visible-light-driven candidate toward sterilizing agent.

A Unique Chemo-photodynamic Antitumor Approach to Suppress Hypoxia via Ultrathin Graphitic Carbon Nitride Nanosheets Supported a Platinum(IV) Prodrug.

Tumor hypoxia severely restrains the efficiency of irreversible O2-consumption photodynamic therapy. The deep hypoxia induced by photodynamic therapy can promote the level of hypoxia inducible factor 1α that participates in many tumor processes and eventually lead to poor therapeutic outcomes. Herein, a chemo-photodynamic antitumor strategy based on ultrathin graphitic carbon nitride nanosheets loaded with a hypoxia-targeting platinum(IV) prodrug is reported. Under low-intensity visible light irradiation, such integrated nanosheets effectively generate reactive oxygen species together with DNA binding platinum species to achieve enhanced antiproliferation efficacy by downregulating HIF-1α under hypoxic conditions.

Enhancement of reverse osmosis membranes for groundwater purification using cellulose acetate incorporated with ultrathin graphitic carbon nitride nanosheets

Modified reverse osmosis (RO) membranes are emerging in the fields of water desalination and purification as next-generation separation techniques. Highly efficient graphitic carbon nitride (g-C3N4) RO membranes were fabricated by incorporating g-C3N4 into polyvinyl alcohol-based cellulose acetate. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy were employed to determine the crystal structure and textural qualities of the ultrathin graphitic layers. The interlayer spacing of the g-C3N4 in the modified membranes was relatively narrow, which significantly impacted membrane performance. Phase inversion was employed to fabricate uniform and compact g-C3N4 hybrid membranes. The impact of the g-C3N4 loading quantity in the polymeric solution on viscosity and membrane performance was investigated. An optimized concentration of 0.5 wt% for the ultrathin g-C3N4 resulted in a distinguished dense top layer. The fabricated RO membranes were evaluated using a synthetic saline solution (2000 ppm of NaCl), resulting in a percentage rejection of 95% at a reasonable operating pressure of 15 bar to exhibit 10.5 LMH. The fabricated membranes exhibited self-cleaning properties after soaking in malachite green dye (10 mgL−l); this demonstrated the antifouling properties of the membrane. The g-C3N4 membrane was successfully applied in a groundwater purification process and its efficiency was observed to reach approximately 97%. This membrane is promising for groundwater treatment.

Optimizing Co site electron structure by construction of heterogeneous interface for efficient sulfite activation on paracetamol removal

Sulfite(S(IV))-induced advanced oxidation processes (AOPs) have great prospect in the field of removing organic pollutants, yet developing highly efficient sulfite activation systems and optimizing active sites for favorable catalytic processes are important but still challenging. Herein, we have achieved a composite catalyst with modulated Co electron structure for efficient AOPs by decorating Co(OH)2 on ultrathin graphitic carbon nitride (g-C3N4) nanosheet through an adjustable strategy, which exhibits high catalytic performance in S(IV) activation system. At optimal pH 9, 92% of paracetamol (APAP) (0.005 mM) is removed with the degradation rate constant of k1 = 0.193 min−1 within 30 min in presence of the composite material. The in-situ synthesis mode introduces strong heterogeneous interface interaction, resulting in directional electron transfer from cobalt hydroxide layer to g-C3N4 sheet revealed by X-ray photoelectron spectroscopy and density functional theory (DFT) calculations. The underlying activity enhanced mechanisms for APAP in S(IV) activation system using Co(OH)2/g-C3N4 are proposed: (i) The ultrathin g-C3N4 nanosheets provide more anchoring centers for generating small Co(OH)2 nanoparticles with abundant active sites which benefit to form metastable intermediates of Co(II)-SO3; (ii) The strong interface interaction induces charge redistribution between Co(OH)2 and g-C3N4 conformed by DFT calculation, which modulates the d-band center of Co site and strengthens the bind of Co(II)-SO3, thereby giving rise to radicals (•OH, SO4• and O2•) and nonradicals (1O2 and electron transfer) oxidation for highly-efficient removal APAP. Our work will pave the way to build an environmentally friendly strategy for emerging organic pollutant degradation in water through building efficient catalysts in sulfite activation system.

Simultaneous decolorization of anionic and cationic dyes by 3D metal-free easily separable visible light active photocatalyst

To overcome the hard and costly post-treatment separation of ultrathin graphitic carbon nitride nanosheets (UGCN), it was supported on polyurethane foam (PUF). The ratio of PUF/UGCN was optimized for the removal of a mixture of methylene blue (MB) and methyl orange (MO) dyes. The characteristics of the composite photocatalyst and its photocatalytic performance were detailly studied. The X-ray diffraction and Fourier transform infrared results proved the successful preparation of UGCN and PUF and that the PUF/UGCN composite combines the features of both pure materials. The transmission electron microscopy illustrated the ultrathin nanosheet shape of the UGCN, while the scanning electron microscope showed the highly porous 3D-hierarchical structure of PUF. Compared to the pure components, the composite photocatalyst with PUF/UGCN mass ratio of 4 achieved better decolorization of MO and almost same decolorization of MB as UGCN. Neutral pH and 1 g/L of the composite photocatalyst were the optimum conditions for MB/MO mixture decolorization. The composite photocatalyst kept its efficiency for five successive cycles. Hydroxyl radicals were the dominant in the degradation of MB, while superoxide radicals were the most influencer in MO degradation. Conclusively, supporting UGCN onto PUF kept the photocatalytic efficiency of UGCN toward MB decolorization and improved its efficiency toward MO. Moreover, it enabled the reuse of the composite photocatalyst and facilitated the post-treatment separation process.

Ultrathin g-C3N4 nanosheet-CoOOH nanocomposite for fluorescence imaging of ascorbic acid in living cells.

Ascorbic acid (AA), a critical cellular metabolite involved in many biochemical pathways, is an important antioxidant in human body. Therefore, it is of great significance to monitor AA in living cells. Nowadays, there are various technologies developed for the detection of AA, but few methods could sensitively and selectively detect the intracellular AA. Here, we reported a highly efficient biosensor (g-C3N4-CoOOH nanocomposite) based on ultrathin graphitic carbon nitride (g-C3N4) nanosheets and CoOOH nanoflakes, for sensitive detection and fluorescence imaging of AA in living cell. The g-C3N4 used here as fluorescence donor is a promising bioimaging nanomaterial because of their high fluorescence quantum yield, good biocompatibility and low toxicity. In addition, the CoOOH was used to be perfect fluorescence quencher. Herein, we enabled the CoOOH in situ to form a layer on the surface of g-C3N4, resulting in fluorescence quench of the g-C3N4. Upon the addition of AA, the CoOOH nanoflakes were reduced to Co2+, and the system gave a "turn on" fluorescence signal. It developed as an efficient sensing platform for AA, and the linear range was from 5 to 50μM with a 1.6μM detection limit. This novel biosensor, g-C3N4-CoOOH nanocomposite exhibited highly selective response toward AA relative to other biomolecules. Furthermore, this biosensor was used successfully to visualize and monitor AA in living cells. Hopefully, we believe that this biosensor would provide a low-cost and highly sensitive platform for AA detection and bioimaging. Schematic illustration of the sensing strategy based on the g-C3N4-CoOOH nanocomposite for AA detection.

Promoted generation of singlet oxygen by hollow-shell CoS/g-C3N4 catalyst for sulfonamides degradation

Sulfanilamide (SM), which is a representative drug of sulfonamides, is commonly used for the prevention and treatment of bacterial infectious diseases and is extremely difficult to remove from water. Herein, an efficient catalyst (CoS/CN) for sulfanilamide degradation was constructed by CoS self-assembling on ultrathin graphitic carbon nitride (g-C3N4) nanosheets. The prepared hollow-shell CoS/CN catalyst could completely degrade SM within 10 min with a rate constant of 2.49 min−1 through the activation of peroxymonosulfate (PMS). Experiments and theoretical calculations indicated that S2− acted as an electron donor for promoting the generation of Co(II). The combination of g-C3N4 and CoS made the CoS/CN composite have higher conductivity and electron transfer ability than CoS, which promoted the decomposition of PMS to produce reactive oxygen species (ROSs). Singlet oxygen (1O2) was proved as the primary ROSs, and SO4− radicals were generated during the 1O2-dominated degradation process to improve the low mineralization rate. 1O2 and SO4− were derived from the oxidation of PMS and the electron transfer of g-C3N4. The results revealed the synergistic effect of free radicals and non-free radicals during the redox of PMS, and provided theoretical support for the efficient degradation of refractory organics in wastewater.

Reactive oxygen species scavenging by hemin-based nanosheets reduces Parkinson’s disease symptoms in an animal model

Mitochondrial damage mediated by reactive oxygen species (ROS) is a major contributory factor to Parkinson’s disease (PD) pathogenesis. The use of hemin-based nanomaterials to control ROS production can protect against neurological damage. Here, we report the rational design of a uniform and water-soluble artificial nanozyme based on an ultrathin graphitic carbon nitride (g-C3N4) nanosheet with loaded hemin to reduce ROS and treat PD. The g-C3N4 not only acted as a scaffold for hemin loading but also improved the stability, cytotoxicity, and catalytic action of hemin. The integration of g-C3N4 increased hemin’s peroxidase activity by 31.7%, promoting effective oxidation of the substrate 3,3′,5,5′-tetramethybenzichne (TMB) in the presence of H2O2 to a blue-colored solution after 10 min’ incubation at room temperature. Moreover, CN-hemin exhibited good biocompatibility and could effectively scavenge intracellular ROS and reduce cytotoxicity induced by H2O2 and 6-hydroxydopamine (6-OHDA). In vivo animal studies using nematode transgenic hus111 strain and 6-OHDA pretreated C. elegans wild-type Bristol (N2) as models further showed that CN-hemin extended their lifespan and restored dopamine-dependent behaviors such as area-restricted searching, ethanol avoidance, and the basal slowing response by reducing ROS-mediated neurotoxicity. Nanomaterials using CN-hemin enzyme mimicry have potential biomedical applications, including the treatment of PD and disorders related to ROS metabolism.

Polydopamine/defective ultrathin mesoporous graphitic carbon nitride nanosheets as Z-scheme organic assembly for robust photothermal-photocatalytic performance

Polydopamine/defective ultrathin mesoporous graphitic carbon nitride (PDA/DCN) Z-scheme organic assembly is fabricated through high-temperature surface hydrogenation and ultrasonic freeze-dried strategies. PDA could be anchored on the surface of DCN with adequate N-vacancy defects firmly via π-π interactions, forming Z-scheme heterogenous structure for promoting charge separation. The visible and near-infrared light driven photocatalytic hydrogen evolution rate is up to 3420 μmol h−1 g−1, and the removal ratio of organic contaminant methylene blue is up to 98% within 70 min, which is several times higher than that of pristine graphitic carbon nitride and DCN. The important reason is the defects of DCN not only enhance the interaction with PDA, but also make the obvious polarized inbuilt electric field, and lead to Z-scheme structure for effective charge separation and rapid transfer, which is also confirmed by density functional theory (DFT) calculations. In addition, PDA extends the photoresponse to the near-infrared region and induces obvious photothermal effect to increase the reaction rate of the photocatalytic system. The efficient photothermal conversion of PDA/DCN should be another reason for the enhanced photocatalytic performance.