Efficient g-C3N4 Research Articles

Surface Optimization of Noble-Metal-Free Conductive [Mn1/4Co1/2Ni1/4]O2 Nanosheets for Boosting Their Efficacy as Hybridization Matrices.

Conductive 2D nanosheets have evoked tremendous scientific efforts because of their high efficiency as hybridization matrices for improving diverse functionalities of nanostructured materials. To address the problems posed by previously reported conductive nanosheets like poorly-interacting graphene and cost-ineffective RuO2 nanosheets, economically feasible noble-metal-free conductive [MnxCo1-2xNix]O2 oxide nanosheets are synthesized with outstanding interfacial interaction capability. The surface-optimized [Mn1/4Co1/2Ni1/4]O2 nanosheets outperformed RuO2/graphene nanosheets as hybridization matrices in exploring high-performance visible-light-active (λ>420nm) photocatalysts. The most efficient g-C3N4-[Mn1/4Co1/2Ni1/4]O2 nanohybrid exhibited unusually high photocatalytic activity (NH4 + formation rate: 1.2mmol g-1 h-1), i.e., one of the highest N2 reduction efficiencies. The outstanding hybridization effect of the defective [Mn1/4Co1/2Ni1/4]O2 nanosheets is attributed to the optimization of surface bonding character and electronic structure, allowing for improved interfacial coordination bonding with g-C3N4 at the defect sites. Results from spectroscopic measurements and theoretical calculations reveal that hybridization helps optimize the bandgap energy, and improves charge separation, N2 adsorptivity, and surface reactivity. The universality of the [Mn1/4Co1/2Ni1/4]O2 nanosheet as versatile hybridization matrices is corroborated by the improvement in the electrocatalytic activity of hybridized Co-Fe-LDH as well as the photocatalytic hydrogen production ability of hybridized CdS.

Nitrogen-oxygen defect engineering enhanced intrinsic electric field in CoFe2O4/g-C3N4 heterojunctions for photocatalytic tetracycline degradation and H2 evolution

A range of efficient g-C3N4/CoFe2O4 heterojunction with nitrogen deficiencies (NDs) and oxygen deficiencies (ODs) were successfully synthesized through doping-melting and hydrothermal methods. Nitrogen-oxygen defect engineering effectively enhanced the active sites on the catalyst surface and regulated the optical bandgap, band structure, and work function (Φ) of g-C3N4 and CoFe2O4, regulating the strength of the intrinsic electric field (IEF) and promoting the separation of photo-generated carriers at the heterojunction interface. Among the series of samples, CH-H2@CFO-A5 (properly oxalate-doped g-C3N4/CoFe2O4 heterojunctions treated with prolonged annealing) demonstrated remarkable optical properties due to its narrowest optical band gap, while the strongest IEF and redox potential make it has strong carrier dynamics and photocatalytic efficiency. Under visible light, the mineralization rate of tetracycline (TC) on CH-H2@CFO-A5 and the photocatalytic hydrogen production rate were 4.51 times and 2.72 times higher than that of unmodified CN-H0@CFO-A1, respectively. This study aimed to provide an efficient strategy for regulating the IEF within the heterojunction, by altering the Fermi level through multi-element defect engineering.

Surface modification of g-C3N4 for enhanced photocatalytic activity via a simple illumination in pure water

The surface of graphitic carbon nitride (g-C3N4) is decisive in its photocatalytic performance because the critical processes including pollutants adsorption, interfacial charge transfer, and redox reaction etc, readily take place on its surface. In this study, a novel surface functionalization strategy was developed to introduce hydroxyl groups on the surface of g-C3N4 through a simple illumination modification in pure water. The specific surface area and morphology of g-C3N4 did not show significant changes after light irradiation modification, but there were significant differences in the composition of surface functional groups, surface charge properties, and photocatalytic activities. A series of characterization results indicated that hydroxyl groups introduction on the surface of g-C3N4 could significantly enhance surface electronegativity, accelerate photogenerated charge carriers separation and transfer, and increase O2•- radicals generation, thereby improving the highly selective adsorption and photocatalytic degradation performance of g-C3N4 for cationic methylene blue (MB) wastewater treatment. This work provides an effective strategy for fabricating efficient g-C3N4 photocatalysts for different kinds of organic wastewater treatment via simple surface modification.

Boosted photocatalytic performance of cobalt ferrite anchored g-C3N4 nanocomposite toward various emerging environmental hazardous pollutants degradation: insights into stability and Z-scheme mechanism.

In this study, a highly efficient CoFe2O4-anchored g-C3N4 nanocomposite with Z-scheme photocatalyst was developed by facile calcination and hydrothermal technique. To evaluate the crystalline structure, sample surface morphology, elemental compositions, and charge conductivity of the as-synthesized catalysts by various characterization techniques. The high interfacial contact of CoFe2O4 nanoparticles (NPs) with g-C3N4 nanosheets reduced the optical bandgap from 2.67 to 2.5eV, which improved the charge carrier separation and transfer. The photo-degradation of methylene blue (MB) and rhodamine B (Rh B) aqueous pollutant suspension under visible-light influence was used to investigate the photocatalytic degradation activity of the efficient CoFe2O4/g-C3N4 composite catalyst. The heterostructured spinel CoFe2O4 anchored g-C3N4 photocatalysts (PCs) with Z-scheme show better photocatalytic degradation performance for both organic dyes. Meanwhile, the efficiency of aqueous MB and Rh B degradation in 120 and 100min under visible-light could be up to 91.1% and 73.7%, which is greater than pristine g-C3N4 and CoFe2O4 catalysts. The recycling stability test showed no significant changes in the photo-degradation activity after four repeated cycles. Thus, this work provides an efficient tactic for the construction of highly efficient magnetic PCs for the removal of hazardous pollutants in the aquatic environment.

Remarkable improvement in photocatalytic activity of g-C3N4 for NO oxidation through surface hydroxylation

The nitrogen oxide emissions originating from combustion pose significant risks to the environment. Photocatalysis is considered an efficient and environmentally friendly strategy to alleviate this problem. Graphitic carbon nitride (g-C3N4) is regarded as one of the most promising organic photocatalytic materials for environmental purification. However, its small specific surface area, weak adsorption and high recombination rate of charge carriers result in low intrinsic photocatalytic activity. To overcome these obstacles, a hydrothermal treatment of dicyandiamide-derived g-C3N4 (DCN) at different temperatures (140–200 °C) was employed to enhance the photocatalytic activity for NO oxidation. The experimental results demonstrated a significant improvement in the photocatalytic oxidation removal rate of NO after a hydrothermal treatment. The optimal photocatalyst, DCN-180, treated at 180 °C, demonstrated the highest NO removal efficiency (65.0 %), which is twice the value of pristine DCN (32.5 %). Additionally, the formation of the toxic intermediate NO2 was effectively suppressed during the reaction. Photoelectrochemical tests revealed that DCN-180 exhibited higher photocurrent density and smaller impedance radius compared to the untreated g-C3N4 sample. Moreover, density functional theory (DFT) calculations confirmed that the DCN-180 sample showed a stronger ability to adsorb O2 and NO. The enhanced photocatalytic NO oxidation performance of DCN-180 has been primarily attributed to its enlarged specific surface area (from 10.7 to 35.5 m2 g−1), local polarization effect, reduced interfacial charge transfer resistance, and improved adsorption abilities for NO and O2 molecules. This study provides valuable insights for designing and preparing highly efficient g-C3N4 based photocatalysts through surface modification for photocatalytic NO purification.

Fabricated layered g-C3N4 nanosheets for high efficiency photocatalytic degradation of atrazine：Insight into terminal-NHx in-situ activation of H2O2

It is well known that graphite-like carbon nitride (g-C3N4) is a good photocatalyst for in-situ the production of H2O2. However, how to activate H2O2 generating the strong oxidizing ·OH is the key factor to affect the degradation of pollutants. In this paper, the layered g-C3N4 nanosheets were prepared by using urea and H2O with different mass ratios and calcined in Muffle furnace by one-step synthesis method. The morphology, composition and structure of photocatalysts were analyzed, indicating that the as-prepared L-g-C3N4-7 had abundant edge regions in comparison with L-g-C3N4 made by solid urea. The photocatalytic performance of g-C3N4 nanosheets was investigated with atrazine (ATZ) as the target pollutant in water. The results revealed that the prepared L-g-C3N4-7 exhibited the best photocatalytic activity in visible light (λ ≥ 420 nm). The degradation of 1.0 mg/L ATZ reached over 96% after 3 hours and the photocatalytic degradation rate constant (k) was 6.8 times than that of L-g-C3N4 photocatalyst. In addition, under the same conditions, the H2O2 production of L-g-C3N4-7 was 4.5 times than that of L-g-C3N4 photocatalyst. Based on the capture experiments of free radicals, it was found that the contribution rate of ·OH in L-g-C3N4-7 photocatalytic increased to 17 % compared to 4 % of L-g-C3N4 photocatalyst during the degradation of ATZ. The ·OH quantitative experiment indicated that the L-g-C3N4-7 photocatalyst could obviously activate H2O2 to generate ·OH and the amount of ·OH was 2.5 times than that of the L-g-C3N4 photocatalyst. More importantly, a large amount of terminal-NHx (14.6 %) in L-g-C3N4-7 was measured by the XPS, FT-IR and zeta potential. The additive H2O2 adsorption experiment in the dark was used to confirm terminal-NHx sites of L-g-C3N4-7 photocatalyst, which was beneficial to adsorb and activate H2O2. The results illustrated that the L-g-C3N4-7 photocatalyst with rich edge regions and terminal-NHx had the characteristics of in-situ the activation of H2O2 to generate ·OH. The findings suggest that designing and developing efficient g-C3N4 photocatalysts pave a new avenue for activating in situ self-synthesizing H2O2 and the removal of atrazine in water.

One-Dimensional Tubular Carbon Nitride Embedded in Ni2P for Enhanced Photocatalytic Activity of H2 Evolution

Graphitic carbon nitride is considered as an ideal semiconductor material for photocatalytic hydrogen evolution due to its suitable energy band structure, durability and environmental friendliness. To further improve the catalytic performance of g-C3N4, nickel phosphide-loaded one-dimensional tubular carbon nitride (Ni2P/TCN) was prepared by thermal polymerization and photo deposition. The beneficial effect of the one-dimensional tubular structure on hydrogen generation was mainly attributed to its larger specific surface area (increased light absorption) as well as the linear movement of the carriers, which reduced their diffusion distance to the surface and facilitated the separation of photogenerated carriers. The loading of Ni2P co-catalyst improved the visible light utilization efficiency and enabled the migration of photogenerated electrons towards Ni2P, which ultimately reacted with the enhanced adsorbed H+ on the Ni2P surface to facilitate the photocatalytic hydrogen evolution process. This study provides new clues for the further development of efficient, environmentally friendly and low-cost g-C3N4 catalysts.

Microstructure driven charge carrier separation in superior thin g-C3N4 nanosheets towards enhanced photocatalytic activities

The performance of graphic carbon nitride (g-C3N4) depended strongly on solar energy harvesting and photogenerated charge carrier separation and transfer. Defect engineering (local component and crystallinity adjustment) helps g-C3N4 to improve photocatalytic activity. In this paper, superior thin g-C3N4 nanosheets with typical microstructures were created using a two-step thermal polymerization at high temperature by adjusting precursors. g-C3N4 nanosheets obtained using melamine revealed fine crystallinity compared with that created using dicyandiamide even though related flat microstructure observed for two samples. In contrast, a wrinkled microstructure with self-assembled amorphous/crystalline junctions was created by urea. Interestingly, the wrinkled one revealed the fastest degradation for RhB which was degraded over within 5 min and a high H2 generation rate of 3473 μmol·g−1·h−1 compared with other samples. This performance is ascribed that wrinkle ultra-thin g-C3N4 nanosheets with amorphous-crystalline junctions significantly improved light harvesting ability and photogenerated carrier separation and transport efficiencies. Furthermore, almost no H2 was generated using molten-salt (NaCl and KCl) assisted porous g-C3N4 nanosheets. These results suggest that increased active sites generated by defect engineering were crucial for the photocatalytic performance of g-C3N4. The detailed discussion on microstructure formation provides an important platform for the construction of highly efficient g-C3N4 based photocatalysts.

Rational design of a g-C3N4/CdS/MIL-125 (Ti)-derived TiO2 ternary heterojunction as a highly efficient photocatalyst for wastewater treatment under visible-light irradiation

A highly efficient g-C3N4/CdS/TiO2 ternary heterojunction photocatalyst with a hollow structure has been fabricated using a step-by-step self-assembly strategy.

Recent Advances in g-C3N4 Photocatalysts: A Review of Reaction Parameters, Structure Design and Exfoliation Methods

Graphitized carbon nitride (g-C3N4), as a metal-free, visible-light-responsive photocatalyst, has a very broad application prospect in the fields of solar energy conversion and environmental remediation. The g-C3N4 photocatalyst owns a series of conspicuous characteristics, such as very suitable band structure, strong physicochemical stability, abundant reserves, low cost, etc. Research on the g-C3N4 or g-C3N4-based photocatalysts for real applications has become a competitive hot topic and a frontier area with thousands of publications over the past 17 years. In this paper, we carefully reviewed the recent advances in the synthesis and structural design of g-C3N4 materials for efficient photocatalysts. First, the crucial synthesis parameters of g-C3N4 were fully discussed, including the categories of g-C3N4 precursors, reaction temperature, reaction atmosphere and reaction duration. Second, the construction approaches of various nanostructures were surveyed in detail, such as hard and soft template, supramolecular preorganization and template-free approaches. Third, the characteristics of different exfoliation methods were compared and summarized. At the end, the problems of g-C3N4 materials in photocatalysis and the prospect of further development were disclosed and proposed to provide some key guidance for designing more efficient and applicable g-C3N4 or g-C3N4-based photocatalysts.

Nanoflower-like graphitic carbon nitride aerogel: Artful cyanuric acid-controlled synthesis and enhanced photocatalytic hydrogen evolution activity

The previously reported studies on cyanuric acid-assembly strategy usually ignores the promoting function of cyanuric acid in the production of g-C3N4, limiting the development of molecular assembly strategies. In this study, a cyanuric acid-controlled synthesis strategy involving the pre-assembly of cyanuric acid with melamine and subsequent one-step calcination was developed to produce a three-dimensional (3D) nanoflower-like graphitic carbon nitride (g-C3N4) aerogel. Some cyanuric acid molecules underwent a polycondensation reaction with melamine during the pre-assembly process and finally polymerized into the g-C3N4 structure during subsequent calcination. Meanwhile, the remaining cyanuric acid molecules assembled with melamine via hydrogen-bond interactions and underwent incomplete decomposition during subsequent calcination, which not only promoted the production of 3D nanoflower-like aerogel structures, but also introduced the carbonyl (CO) and hydroxyl (–OH) groups onto the g-C3N4 surface, resulting in the successful generation of a 3D nanoflower-like oxygen-modified g-C3N4 aerogel. Moreover, the fabricated g-C3N4 aerogel exhibited a greatly enhanced H2 production rate (1573 μmol h−1 g−1), which is ∼ 6.6 times higher than that of bulk g-C3N4 (239 μmol h−1 g−1) owing to the synergistic promotion function of ultrathin nanoflower-like aerogel and oxygen modification structures. This strategy provides a theoretical basis for the development of highly efficient g-C3N4 photocatalysts via molecular assembly.

One-step synthesis of S-doped C-vacancy g-C3N4 with honeycomb porous nanosheets structure for efficient visible-light-driven hydrogen evolution

A defective construction method was applied to design the molecular framework from the source and use the intermolecular forces of the raw materials to connect the long chains. The S-doped honeycomb g-C3N4 nanosheets were prepared by selective volatilization at elevated temperatures using melamine-tricyanuric acid-thiourea supramolecular liquid as precursor and template. In addition to significantly increasing the high surface area, the S-doped honeycomb g-C3N4 nanosheets also modify the band gap structure and shape. The introduction of the C defect also increased the number of reaction sites, improved visible light responsiveness, broadened the photoresponse range, and accelerated the segregated transfer of photogenerated carriers. The experimental results showed that the hydrogen production efficiency of S-PDCN-3 (The best sample of S-doped C-vacancy g-C3N4) is 23.78 mmol‧g−1‧h−1, which was 21.8 times that of BCN, namely Bulk g-C3N4 (1.1 mmol‧g−1‧h−1). After adding the photosensitizer (Erythrosin B) to the photocatalytic reaction system, EB + S-PDCN-3 (the best sample of S-doped honeycomb g-C3N4 nanosheets with the sensitizer) precipitated hydrogen up to 63.8 mmol‧g−1‧h−1, which was 17.78 times greater than the hydrogen production of the EB + BCN sample (3.59 mmol‧g−1‧h−1). Furthermore, the sample was observed to experience a reduction in band gap energy, an increase in electron density near VB and a reduction of H* adsorption–desorption barrier, all of which are essential for the enhancement of the hydrogen evolution reaction. Successful preparation of S-doped honeycomb g-C3N4 nanosheets provides a simple and efficient method for developing efficient g-C3N4 photocatalysts—potential applications in the development process of hydrogen energy and pollutant degradation.

Hydrogen generation from hydrolysis of NaBH4 solution with efficient g-C3N4/Co–Mo–B/Ni foam catalyst

Sodium borohydride (NaBH4) is considered to be a perfect material for hydrogen production in consideration of the high hydrogen capacity. However, the catalyst with low cost and high activity is the key to achieving dehydrogenation from the hydrolysis of NaBH4 solution. In this work, we successfully synthesized g-C3N4/Co–Mo–B/Ni foam catalyst by means of chemical deposition at 298 K. The catalytic property of g-C3N4/Co–Mo–B/Ni foam for NaBH4 hydrolysis was investigated via regulating the molar ratio of Co2+ and MoO42− (nCo2+:nMoO42−). The results disclosed that the obtained g-C3N4/Co–Mo–B/Ni foam showed the optimum catalytic property when the nCo2+:nMoO42− value was 1:1. Its hydrogen generation rate (HGR) and apparent activation energy (Ea) were respectively determined to be 9957.7 mL min−1·g−1 and 52.6 kJ mol−1 under visible light irradiation, which has obviously exceeded the performance under darkness (HGR = 8372.7 mL min−1·g−1, Ea = 55.8 kJ mol−1). It might attribute to the emergence of Mo2C during the preparation process which attracted the photoelectron transfer on g-C3N4, thus promoting the photocatalytic hydrolytic process of NaBH4 solution. Moreover, the smaller grain size and synergistic effect between multiple components could be another reason for heightening the catalytic dehydrogenation property of g-C3N4/Co–Mo–B/Ni foam catalyst.

Vacancy-Modified Porous g-C3N4 Nanosheets Controlled by Physical Activation for Highly Efficient Visible-Light-Driven Hydrogen Evolution and Organics Degradation.

As a promising photocatalyst material, g-C3N4 has great application potential in energy production and environmental improvement. In this work, surface-modified g-C3N4 nanosheets with excellent stability and high photocatalytic activity were successfully synthesized by physical steam activation. The charge transfer rate of carbon nitride was improved due to the synergistic effect of nitrogen defect and oxygen doping caused by steam activation. Meanwhile, the specific surface area and pore volume of the optimized sample reached 124.3 m2 g-1 and 0.42 cm3 g-1, respectively, which increased the exposed reaction sites of reactants, enhancing the photocatalytic activity of g-C3N4. In addition, this novel g-C3N4 displayed a great H2 evolution rate of 5889.39 μmol h-1 g-1 with a methylene blue degradation rate up to 6.52 × 10-3 min-1, which was 3.7 and 2.1 times of original g-C3N4, respectively. This study provided a simple and economical method to develop a highly efficient g-C3N4 photocatalyst for solar energy conversion.

One-step synthesis of porous thin-layered graphitic carbon nitride for enhanced photocatalytic dye degradation

The application of graphitic carbon nitride (g-C3N4) as a non-metallic photocatalyst for removing harmful pollutants in the wastewater environment has received considerable attention in recent years. Nevertheless, its low activity is primarily restricted by a high rate of charge carrier recombination. Herein, a green and straightforward method for synthesizing small-sized porous thin g-C3N4 nanosheets directly from urea solution has been developed. This new photocatalyst can effectively remove 99.3% of rhodamine B within 15 min, exhibiting a degradation rate 16.8 times greater than that of conventionally synthesized bulk g-C3N4, under visible light irradiation. Additionally, this photocatalytic efficiency is comparable or even superior to that of previously reported literature, while requiring significantly less catalyst usage. From the experimental results, we have confirmed that the outstanding structural property as well as the stronger oxidizability of the valence-band holes (h+) are responsible for its greater photocatalytic activity. Its increased specific surface area and abundant pore structure significantly improve contaminant adsorption and charge separation and transfer. Meanwhile, the positive shift of the valence band enhances the oxidation of photogenerated h+, resulting in higher photocatalytic activity. This work can provide newly insights for designing highly efficient and easily-constructed g-C3N4 photocatalysts for practical photocatalytic water treatment applications.

Decoration of rutile TiO2 nanorod film with g-C3N4/SrTiO3 for efficient photoelectrochemical cathodic protection

A highly efficient g-C3N4/SrTiO3 co-decorated rutile TiO2 nanorod composite film photoanode was fabricated on a conductive glass substrate by a three-step synthesis process involving hydrothermal reactions and chemical vapor deposition. The g-C3N4/SrTiO3/TiO2 composite film with an appropriate cascade energy band structure showed greatly improved visible light absorption and exhibited 4.5 times higher photocurrent density than the undecorated TiO2 film, resulting from its higher separation and transfer efficiency of the photogenerated electron-hole pairs. Under the white light irradiation, the composite film photoanode made the potential of the coupled 403 stainless steel in a 0.5 M NaCl solution decrease by 680 mV from its free corrosion potential, showing a significantly enhanced photoelectrochemical cathodic protection effect.

Rational optimization of g-C3N4/Co3O4 nanocomposite for enhanced photodegradation of Rhodamine B dye under visible light

Heterogeneous catalysis is widely known as an efficient, clean, and low-cost technology to mitigate the environmental pollution of industrial effluents. This research aimed at optimizing the preparation and characterization of efficient g-C3N4/Co3O4 nanocomposite for catalytic removal of Rhodamine B (Rh B) dye. The detected XRD peaks for the prepared nano-Co3O4 are matched with the cubic crystal structure. In contrast, the broad peak at 27.3° corresponding to the graphite reflection of hkl (002) was noticeably weakened in the XRD pattern of the g-C3N4/Co3O4 composite. FTIR spectra of g-C3N4/Co3O4 nanocomposites revealed the active vibrational modes of each Co3O4 and g-C3N4 component. The microstructure study of g-C3N4 showed the strong interlayer stacking of carbon nitride nanosheets, while the surface morphology of g-C3N4/Co3O4 nanocomposite revealed a hybrid particulate system. EDS analysis indicated that the spot area of g-C3N4/Co3O4 confirmed the chemical ratios of carbon, nitrogen, cobalt, and oxygen. BET measurements of g-C3N4/Co3O4 showed a significant increase in the surface area and pore volume of single components due to the lamination of stacked g-C3N4 nanosheets by the intercalated Co3O4 nanoparticles. The prepared 30% g-C3N4/Co3O4 revealed the lowest value of Eg ~1.2 eV and the highest light absorptivity suggesting strong promotion for the photocatalytic performance under visible light. The maximum photocatalytic activity of about 87% was achieved by 30% g-C3N4/Co3O4 due to the photonic enhancement, which reduces the recombination of excited electrons. The developed nanocomposite with a g-C3N4/Co3O4 ratio of 0.3 exhibited high stability in its photocatalytic performance after four recycling times, and a slight decrease of about 7% was estimated after the 5th reuse test.

Environmentally friendly supermolecule self-assembly preparation of S-doped hollow porous tubular g-C3N4 for boosted photocatalytic H2 production

Utilization of graphitic carbon nitride (g–C3N4)–based materials for photocatalytic hydrogen production to alleviate energy problems is a hot topic of research nowadays, thus the design and synthesis of highly efficient g-C3N4 materials remains a significant challenge. Herein, the sulphur-doped hollow porous tubular g-C3N4 (S-HPTCN) was successfully synthesized by a facile environmentally friendly supramolecule self-assembly strategy. Photocatalytic H2 evolution tests show that the as-prepared optimal S-HPTCN achieved a high H2 production of up to 22.04 mmol g−1 h−1 with the turnover frequency (TOF) of 429.7 h−1 and the apparent quantum efficiency (AQE) of as high as 7.8% at wavelength of 420 nm. The enhancement of remarkable photocatalytic H2 performance is mainly attributed to the synergetic effect of morphology and elemental doping. This research provides an effective design idea of developing high-efficient g–C3N4–based material for solar to hydrogen.

N-doped synergistic porous thin-walled g-C3N4 nanotubes for efficient tetracycline photodegradation

Metal-free g-C3N4 has received wide attentions because of the economy and environmental friendliness of it. However, the synthesis of simple and efficient g-C3N4 modified materials is still challenging. In this study, series of novel N-doped porous thin-walled g-C3N4 nanotubes (CNx) were synthesized through supramolecular self-assembly and thermal polymerization using melamine and aminourea hydrochloride as raw materials. SEM, XRD, XPS, etc. were used to analyze microscopic morphology and chemical structure of synthesized photocatalysts. PL spectra, EIS Nyquist curves and UV–vis DRS, etc. were applied to study the photoelectrochemical and optical properties. Besides, the performance of the synthesized catalysts was illustrated through TC photodegradation experiments, and the degradation rate of tetracycline (TC) by CN0.75 can reach to 93.0 % and the reaction rate constant was calculated to be 0.1347 min−1. The excellent photocatalytic activity is primarily related to higher specific surface area and the formation of midgap states after N doped, which is conducive to the separation of charges. Finally, the possible pathways and mechanisms were proposed by determining the degradation intermediates and active species in the TC photodegradation process.

High efficient and stable Z-scheme g-C3N4/Zn0.5Cd0.5S photocatalyst driven by visible light for hydrogen evolution

It is extremely desirable to develop efficient and cheap water splitting photocatalysts. An ultrahigh performance and stable photocatalyst g-C3N4/Zn0.5Cd0.5S was prepared by simple sintering method. g-C3N4nanosheets are evenly distributed around 20–30 nm ZnCdS nanoparticles, which can accelerate carriers separation and transfer, and increase the carriers life-time from 4.1 ns to 5.5 ns. UV–vis absorption spectra demonstrate that their absorption range can reach to visible light edge of 539 nm. The photocatalyst has a high photocatalytic hydrogen evolution rate of 16.66 mmol•h−1•g−1 under visible light illumination (λ = 400–780 nm). Furthermore, after six recycles of photocatalyst, the hydrogen evolution stability still remains 94%. The excellent photocatalytic performance is attributed to the Z-scheme energy band structure formed between g-C3N4 and Zn0.5Cd0.5S by simple sintering method. This work provides significant progress toward the synthesis of cheap Z-scheme photocatalysts for practical applications.