Nanoporous Graphitic Carbon Nitride Research Articles

Broad-spectrum hybrid-driven triple-interface Z-Scheme 1T/2H phase sailboat-like molybdenum disulfide (MoS2)/protonated N-defect nanoporous graphitic carbon nitride (g-C3N4) nanosheets piezo-photocatalyst: Superior degradation and hydrogen evolution

Incorporating piezo-response into photocatalysis holds great promise for eco-friendly strategies in environmental remediation and sustainable energy conversion. Herein, flexible N-defect nanoporous g-C3N4 nanosheets (NPCNs) was prepared via one-step method, then whose surface was protonated. And existed dense 1T/2H phase and vertical interfaces in non-layer-dependent-piezo-response sailboat-like-MoS2 (Sv-MS) formed by in-situ stresses during nucleation and growth by experiments and MD-simulations. Noble-metal-free Z-scheme PC/VM heterojunction with broad-spectrum absorption, enhanced piezo-response and intimate triple-interface was established by electrostatic self-assembly, performing efficient hybrid-driven piezo-photocatalysis. With a systematic modification of morphology, grain size, phase composition, and surface condition of the components, the optimal PC(3.6H)/VM(u2) exhibited high piezo-photocatalytic rates for degradation of organic dyes and antibiotic (RhB (0.565 min-1), MO (0.052 min-1), MB (1.557 min-1), TC (0.062 min-1)) and hydrogen evolution (3528 μmolg-1h-1) under visible-light and ultrasonic-wave, with maintenance under NIR-light (λmax = 1000 nm) attributed to up-conversion effect (RhB: 0.212 min-1, H2: 2355 μmolg-1h-1). Furthermore, the piezo-photocatalytic mechanism was proposed by experiments and DFT-calculations for effective triple-interface Z-Scheme charge migration. This work provides a rational protocol for constructing diverse-energy-triggered, multiple-interfaces and broad-solar-spectrum (UV–Vis-NIR) piezo-photocatalysts in degradation and hydrogen evolution.

Nanoporous Graphitic Carbon Nitride as Catalysts for Cofactor Regeneration

An efficient nicotinamide adenine dinucleotide (NADH) regeneration system is of great significance for the application of oxidoreductase-catalyzed reactions. Photochemical regeneration has been a research hotspot in recent years. Graphite carbon nitride (g-C3N4) has important application prospects. However, bulk g-C3N4 (BCN) has some disadvantages that lead to a low catalytic efficiency. Herein, nanoporous g-C3N4 (PCN) was prepared using silica nanoparticles as templates, and the effects of the mass ratio of cyanamide to silica and the particle size of the templates on the structure, optical, and catalytic properties of PCN were investigated. Then, cyanamide was separately co-polymerized with two types of thiophene compounds and imidazole-, benzene-, and quinolone-based compounds, and the effects of the structure and number of aromatic rings introduced into PCN on the properties of catalysts were studied. The results show that PCN had much better catalytic performance than BCN, the initial reaction rate of NADH regeneration could be upgraded from 18.01 to 37.14 mmol/(g·min) after PCN was modified with thiophene compound, and the yield of NADH after 20 min increased from 56.8 to 82.7%. When other aromatic compounds were added in the PCN preparation process, a catalytic performance similar to that of thiophene-modified PCN was acquired.

Nanoporous Graphitic Carbon Nitride Nanosheets Decorated with Nickel–Cobalt Oxalate for Battery-Like Supercapacitors

Nanoporous Graphitic Carbon Nitride Nanosheets Decorated with Nickel–Cobalt Oxalate for Battery-Like Supercapacitors

Molecular dynamics simulation-directed rational design of nanoporous graphitic carbon nitride membranes for water desalination

As a novel two-dimensional material, graphitic carbon nitride (g-C3N4) has proved to be promising for separation membrane. However, the assessment of nanoporous g-C3N4 membrane for efficient desalination process has not been systematically investigated yet. In this work, we designed three g-C3N4 nanopores with different shapes based on the membrane unit structure. The non-equilibrium molecular dynamics simulations were used to study the molecular mechanism of saline water permeation through the nanoporous g-C3N4 membranes. The relationship between water flow rate and external pressure was in good agreement with the classical hydrodynamics. Meanwhile, we observed that the local water diffusion coefficient increased as the enlargement of nanopore sizes, indicating that the nano-effect may also rule the water permeation. For desalination purposes, the designed g-C3N4 nanoporous membrane entirely rejected ions while maintaining a considerable water permeability of 14.9 L/cm2/day/MPa. By analyzing the trajectories of ions passing through the nanopores, we found that the configurational shape could divide one nanopore into several sub-regions, and specific ones may determine the desalination performance of the nanoporous membrane. This work unveils the molecular insights into the desalination process of nanoporous g-C3N4 membrane and further provides useful guidelines for the design of next generation desalination membranes with complex nanopore structures.

Adsorption and photocatalytic degradation of aqueous methylene blue using nanoporous carbon nitride

Nanoporous graphitic carbon nitride (npg-C3N4) with high performance was synthesized as visible light harvesting photocatalyst. Calcium carbonate (CaCO3) nanoparticles were synthesized and used as a templating agent along with melamine, as the precursor, for the synthesis of npg-C3N4. High porous npg-C3N4, having a specific surface area of 137.4 m2 g−1, was resulted with enhanced ability in visible light harvesting. At the mass ratio of melamine/CaCO3 = 5/4, its photocatalytic performance was 42 times higher than that of the bulk g-C3N4 when methylene blue (MB) was used as adsorbate and probe. Adsorption and kinetic isotherm showed that the adsorption process can be well described by pseudo-second-order kinetic model, with an adsorption capacity of 400.0 mg MB per gram adsorbent determined by Langmuir isotherm.

Facile synthesis of nanoporpous graphitic carbon nitride photocatalyst coupled with N-doped graphene quantum dots for efficient photo-degradation dyes under nature solar light radiation

Nanoporous graphitic carbon nitride modified with N-doped graphene quantums dots (N-GQD@npg-C3N4) was prepared via a one-pot co-sintering method. The presented N-GQD@npg-C3N4 showed a high photocatalytic activity (PCA) for the degradation of organic dyes under solar radiation. This result can be ascribed to two reasons: (i) the uniform distribution of N-GQDs on the surface of npg-C3N4, which allows for an accelerated electron transfer from npg-C3N4 to N-GQD; and (ii) the unique nanoporous structure of npg-C3N4, providing a large active surface area. This work opens up a new avenue for the utilization of a robust, cost-effective and metal-free photocatalyst in practical applications, e.g. waste water treatment.

Carbon Nitride Grafted Cobalt Complex (Co@npg‐C3N4) for Visible Light−Assisted Esterification of Aldehydes

AbstractAzide containing bipyridine complex of cobalt was grafted to the propargylated nanoporous graphitic carbon nitride (npg‐C3N4) via click reaction to obtain heterogenized photocatalyst which could efficiently provide direct esterification of aldehydes under visible light irradiation at room temperature. The use of click reaction as grafting strategy provided covalent attachment of the cobalt complex to support which not only provided higher loading but also precluded the leaching. Furthermore, the presence of carbon nitride support exhibited synergistic effect to enhance the reaction rate. In addition, the milder basic nature of nitrogen containing graphitic support provided efficient ester synthesis without the need for an external base. The synthesized photocatalyst was found to be quite robust which could easily be recovered and reused several times without significantly losing activity.

Preparation of size-tunable SnS2 nanocrystals in situ adjusted by nanoporous graphitic carbon nitride in the process of hydrothermal synthesis with enhanced photocatalytic performance

A series of size-tunable SnS2 nanocrystals in situ adjusted by nanoporous graphitic carbon nitride (npg-C3N4) in different mass ratios (5:100–20:100) to the SnS2 products during hydrothermal synthesis were successfully prepared. The structures, Brunauer-Emmett-Teller (BET) specific surface areas, morphologies, optical properties and components of the resultant SnS2 were studied by the corresponding characterizations. The results were an undefiled hexagonal phase SnS2 without residual npg-C3N4, and the crystal sizes and energy gaps of the synthetic SnS2 gradually decreased with the increasing added amount of npg-C3N4, while the opposite trend was observed for the BET specific area. The photocatalytic performance was investigated through the visible-light driven (λ>405nm) photocatalytic degradation of methyl orange (MO), and the SnS2 adjusted by 5:100npg-C3N4 showed the highest photocatalytic activity. The results of the characterizations and photocatalytic tests indicated that the use of npg-C3N4 as a template to control the size of SnS2 nanocrystals is a feasible and effective method, and it could potentially be generalized to the preparations of other nanoparticles that need size control.

Long-Life and High-Areal-Capacity Li-S Batteries Enabled by a Light-Weight Polar Host with Intrinsic Polysulfide Adsorption.

Lithium-sulfur batteries are attractive electrochemical energy storage systems due to their high theoretical energy density and very high natural abundance of sulfur. However, practically, Li-S batteries suffer from short cycling life and low sulfur utilization, particularly in the case of high-sulfur-loaded cathodes. Here, we report on a light-weight nanoporous graphitic carbon nitride (high-surface-area g-C3N4) that enables a sulfur electrode with an ultralow long-term capacity fade rate of 0.04% per cycle over 1500 cycles at a practical C/2 rate. More importantly, it exhibits good high-sulfur-loading areal capacity (up to 3.5 mAh cm(-2)) with stable cell performance. We demonstrate the strong chemical interaction of g-C3N4 with polysulfides using a combination of spectroscopic experimental studies and first-principles calculations. The 53.5% concentration of accessible pyridinic nitrogen polysulfide adsorption sites is shown to be key for the greatly improved cycling performance compared to that of N-doped carbons.

Superior nanoporous graphitic carbon nitride photocatalyst coupled with CdS quantum dots for photodegradation of RhB

Nanoporous graphitic carbon nitride (npg-C3N4) shows much higher photocatalytic activities than bulk g-C3N4. Npg-C3N4 was used to couple with CdS quantum dots (QDs) by a simple deposition method to further increase the photocatalytic activities of the photocatalyst. The obtained photocatalyst was characterized by XRD, FT-IR, and XPS techniques; nitrogen adsorption isotherms, SEM and TEM images; and UV–vis DRS and Photoluminescence spectra. Results showed that the CdS QDs had been successfully deposited onto the surface of npg-C3N4 with a good dispersion, and the two components formed stable composites because the CdS QDs can be anchored by the rolled and curled edges of npg-C3N4. The as-prepared CdS QDs/npg-C3N4 composites not only exhibited extended optical absorptions of visible light (up to 600nm) and enhanced photocatalytic activity for the photodegradation of Rhodamine B than each of the components, but also showed good catalytic stability.

A template induced method to synthesize nanoporous graphitic carbon nitride with enhanced photocatalytic activity under visible light

A template induced method was developed to synthesize nanoporous graphitic carbon nitride (npg-CN) by directly heating Triton X-100-modified-melamine sulfate. The effects of the added amount of Triton X-100 and heating temperature on the formation of npg-CN were investigated. The npg-CN samples were characterized by XRD, FT-IR, and elemental analysis; nitrogen adsorption isotherms, SEM and TEM images; and UV-vis DRS and photoluminescence spectra. The results showed that the npg-CN samples possessed a laver-like layered structure with a high surface area (50–135 m2 g−1). Meanwhile, compared to the bulk g-CN (synthesized by directly heating melamine), the npg-CN samples possessed stronger optical absorptions, narrower band gaps, and significantly reduced fluorescence intensity. The photocatalytic activity was investigated by degradation of Rhodamine B under visible light irradiation. As a result, the photodegradation rate of Rhodamine B dye on the npg-CN samples was greatly improved over that on bulk g-CN.

Highly efficient heterojunction photocatalyst based on nanoporous g-C3N4 sheets modified by Ag3PO4 nanoparticles: Synthesis and enhanced photocatalytic activity

Novel visible-light-driven heterojunction photocatalyst composed by Ag3PO4 nanoparticles and nanoporous graphitic carbon nitride sheets (Ag3PO4/p-g-C3N4) was synthesized by a facile and green method. The results showed that photocatalytic activity of Ag3PO4/p-g-C3N4 was much higher than that of pure p-g-C3N4 in the photodegradation of Rhodamine B under visible light irradiation. The kinetic constant of Rhodamine B degradation over Ag3PO4 (33.3mol%)/p-g-C3N4 was about 5 and 2 times higher than that over pure p-g-C3N4 and Ag3PO4, respectively. The enhanced photocatalytic performance is attributed to the stronger visible light absorption and the heterojunction between Ag3PO4 nanoparticles and p-g-C3N4, which could induce the low recombination rate of photoinduced electron–hole pairs.

Nanoporous Graphitic Carbon Nitride with Enhanced Photocatalytic Performance

Nanoporous g-C3N4 (npg-C3N4) with high surface area was prepared by a bubble-templating method. A higher calcination heating rate and proportion of thiourea can result in a larger surface area and better adsorption and photodegradation activities of npg-C3N4. Compared with the bulk g-C3N4, the adsorption capacity for the target pollutants and photocatalytic degradation and photocurrent performances under visible light irradiation of npg-C3N4 were greatly improved. The optimal photodegradation activity of npg-C3N4 was 3.4 times as high as that of the bulk g-C3N4. The enhanced activities of npg-C3N4 can be attributed to the larger number of surface active sites, improved separation of photogenerated electron-hole pairs, and higher efficiency of charge immigration.

Template-directed synthesis of highly ordered nanoporous graphitic carbon nitride through polymerization of cyanamide

The fabrication of well-ordered nanoporous graphitic carbon nitride by condensation of cyanamide (CN–NH 2) as a molecular precursor using a colloidal silica crystalline array as a template is described. The resulting sample exhibited a three-dimensionally extended highly ordered pore array as shown by transmission electron microscopy, scanning electron microscopy and nitrogen isotherms. The carbon nitride structure revealed high graphitic nature with C 3N 4 stoichiometry. In particular, the C 3N 4 network structure consists of tri- s-triazine rings (C 6N 7) cross-linked by trigonal N atoms.