Mesoporous Graphitic Carbon Research Articles

Highly Mesoporous g-C3N4 with Uniform Pore Size Distribution via the Template-Free Method to Enhanced Solar-Driven Tetracycline Degradation.

A highly mesoporous graphitic carbon nitride g-C3N4 (GCN) has been produced by a template-free method and effectively photodegrade tetracycline (TC) antibiotic under solar light irradiation. The mesoporous GCN (GCN-500) greatly improves the photoactivity (0.0247 min−1) by 2.13 times, as compared to that of bulk GCN (0.0116 min−1). The efficiently strengthened photoactivity is ascribed to the high porosity (117.05 m2/g), and improves the optical absorption under visible light (Eg = 2.65 eV) and good charge carrier separation efficiency. The synthesized mesoporous GCN shows a uniform pore size (~3 nm) distribution. GCN-500 shows large pore volume (0.210 cm3/g) compared to GCN-B (0.083 cm3/g). Besides, the GCN-500 also exhibits good recyclability and photostability for TC photodegradation. In conclusion, GCN-500 is a recyclable photocatalyst for the removal of TC under visible light irradiation.

3D mesoporous ultra-thin g-C3N4 coupled with monoclinic β-AgVO3 as p-n heterojunction for photocatalytic hydrogen evolution

In this study, 3D mesoporous ultra-thin graphite carbon nitride (UCN) was successfully prepared using a simple hydrothermal pretreatment route and annealing step. The β-AgVO3 nanorods prepared by the hydrothermal method were uniformly anchored into the UCN network, and a novel type of UCN/β-AgVO3 p-n heterojunction photocatalyst was synthesized. The porous structure not only provides more surface active sites for hydrogen production, but also facilitates mass transfer at the contact interface between UCN and β-AgVO3. UV–Vis diffuse reflectance spectroscopy and fluorescence tests showed that UCN/β-AgVO3 exhibits excellent visible light trapping ability and broadened spectral absorption range, extending the life of photoinduced carriers. The results of photoelectric chemistry tests revealed that the composite material has more effective charge separation efficiency and greatly reduces the hydrogen evolution overpotential. The overall structure effectively promotes the utilization of photosensitizer and sacrificial agents, and achieves excellent hydrogen evolution efficiency. This work provides a feasible strategy for the rational design of binary synergistic photocatalytic systems with porous nanomaterials as the core.

Excellent stability of Pd/mpg-C3N4 in catalytic hydrodebenzylation of 2,4,6,8,10,12-Hexabenzyl-2,4,6,8,10,12- hexaazaisowurtzitane (HBIW)

The low stability and poisoning of the palladium-based catalysts in the debenzylation of HBIW elevated the cost of the hydrogenolysis, and thus restricted the application of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW). To address this problem, Pd/mpg-C3N4 was prepared by depositing palladium nanoparticles on mesoporous graphite carbon nitride (mpg-C3N4), and used for the catalytic hydrogenolysis in the conversion of HBIW to TADBIW under the atmospheric pressure. After optimizing the reaction condition and the usage amount, the highest yield of 81.7 % was obtained at 45℃ after reaction for 8 h when the ratio of palladium to HBIW was 1%. A yield of 74 % was obtained when the ratio of palladium to HBIW was 0.4 %. More importantly, Pd/mpg-C3N4 can be recycled unprecedently for three times in the conversion of HBIW to TADBIW while preserving the reasonable activity. Such results should benefit for promoting the application of HNIW and also the design of the heterogeneous catalysts for hydrodebenzylation.

Enhanced photocatalytic degradation of dimethyl phthalate by magnetic dual Z-scheme iron oxide/mpg-C3N4/BiOBr/polythiophene heterostructure photocatalyst under visible light

A new magnetic dual Z-scheme heterostructure photocatalyst, consisting of mesoporous graphitic carbon nitride (mpg-C3N4), BiOBr, polythiophene (PTh), and magnetic iron oxide, was developed, and its structural, optical, and electrochemical properties were analyzed. The photocatalyst was employed for the degradation of dimethyl phthalate (DMP) in water under visible light to evaluate its photocatalytic activity. The results revealed that the photocatalytic activity of the new heterostructure photocatalyst was superior to that of its single-component counterparts. The reaction kinetics of photocatalytic DMP degradation followed pseudo first-order kinetics and the reaction rate constant was 3.7- and 4.5-fold higher than those of pristine g-C3N4 and BiOBr, respectively. The enhanced photocatalytic performance was chiefly attributed to the dual Z-scheme heterostructure generated between mpg-C3N4, PTh, and BiOBr, which effectively hindered the recombination of photogenerated electron and hole pairs in mpg-C3N4 and BiOBr, improving the photogenerated carrier transfer efficiency. Radical trapping test results indicated that the active species, h+, ·O2–, and ·OH, coexisted during the photocatalytic reaction process, and that h+ played a major role in the destruction of DMP molecules. DMP was degraded into intermediate small-molecule products, such as acids and alcohols, which were ultimately mineralized to CO2 and H2O. The magnetic property of the new heterostructure photocatalyst enabled its straightforward separation from water using magnetic separation technology for further reuse. This study provides a new material and method for the effective removal of DMP from aqueous solution.

Acid-directed preparation of micro/mesoporous heteroatom doped defective graphitic carbon as bifunctional electroactive material: Evaluation of trace metal impurity

Extensive research to explore cost-effective carbon materials as electrocatalysts and electrode materials for energy conversion and storage has been conducted in the recent literature. This raised a crucial question regarding the origin of this electrocatalytic activity from the heteroatom doping/ hierarchical porous defect-rich architecture and/ or the trace metal impurities introduced during synthesis/ inherent to the precursor. In this work, an insight into this issue is provided by considering a lignocellulosic biowaste, Euryale Ferox (foxnut) shells as a precursor to derive micro/ mesoporous defective graphitic carbon sheets by the phosphoric acid (H3PO4) dictated in-situ carbonization for oxygen reduction reaction (ORR) and supercapacitor applications. The sample synthesized at 900 °C (FP900) shows an onset potential of 0.98 V vs. reversible hydrogen electrode (RHE), ORR current density of 5.5 mA cm−2, and current stability of 93% (in 10 h measurement) in 0.1 M KOH. In addition, a symmetric supercapacitor device is assembled using the prepared material and the specific capacitance of 207.5 F g−1 at 1 A g−1 is obtained. An attempt to explain the origin of the electrochemical performance is made by establishing parallels with the physicochemical characterizations. The inherently doped heteroatoms give rise to electroactive functionalities and the wide enough pore size distribution improves the active sites utilization efficiency by enhancing the accessibility to electrolytic ions resulting in better electrochemical performance. Furthermore, the contribution from the intrinsic trace metal impurities is evaluated using X-ray fluorescence (XRF) spectroscopy. The presented research clarifies the non-contributing nature of trace metal species owing to the inaccessibility of active sites and lower abundance in F900 and FP900, respectively.

Acid-assisted synthesis of nitrogen-deficient mesoporous graphitic carbon nitride for hydrogen storage

Defect engineering is an important strategy to tune the surface physical and chemical properties of carbon nitride materials. Herein, a nitrogen-deficient mesoporous graphitic carbon nitride (ND-MCN) with a high specific surface area of 62.6 m2 g−1 was synthesized via hydrochloric acid-assisted thermal polycondensation of melamine and its potential application in hydrogen storage was investigated. Hydrochloric acid acting as activation agent can increase the specific surface area of carbon nitride, and introduce nitrogen-vacancy defects into the framework, leading to a stronger interaction between ND-MCN and hydrogen molecules. As a result, the ND-MCN shows a high hydrogen storage density of 6.39 × 10−3 wt%·g m−2 at 298 K under 20 bar.

Cur-loaded magnetic ZnFe2O4@mZnO-Ox-p-g-C3N4 composites as dual pH- and ultrasound responsive nano-carriers for controlled and targeted cancer chemotherapy

Curcumin (Cur)-loaded zinc ferrite-mesoporous (m) zinc oxide core–shell -oxygen functional groups (carboxyl, carbonyl and hydroxyl) rich mesoporous (p) graphitic (g) carbon nitride (ZnFe2O4@mZnO-Ox-p-g-C3N4) carriers were designed as a potential magnetic drug delivery carrier with pH and ultrasound sensitivity for targeted drug delivery. Application of focused ultrasound can be an effective stimulant for highlighting tumor tissue or activatng delivery of echogenic drugs, which is expected to lower the systemic side effects of chemotherapy. The mixed application of physical/external (ultrasound) and chemical/internal (pH) triggers can allow for targeted release of Cur at chosen sections of tumor tissue. ZnFe2O4@mZnO and ZnFe2O4@mZnO-p-g-C3N4 nano-carriers were characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier rransform infra-red (FTIR) spectroscopy, dynamic light scattering (DLS), zeta potential analysis, transmission electron microscopy (TEM), BET (Brunauer–Emmett–Teller), vibrating sample magnetometery (VSM), thermogravimetric analysis (TGA) and in vitro cytotoxicity assays. The ZnFe2O4@mZnOand ZnFe2O4@mZnO-Ox-p-g-C3N4 magnetic nano-carriers showed high loading efficiency of 51.39 and 67.37%, respectively, were stable in water for 24 h. The carriers Nano-carriersshowed pH- and ultrasound-sesnsitive release of Cur. The release at pH = 5.5 for (ZnFe2O4@mZnO 70.28%) (ZnFe2O4@mZnO-Ox-p-g-C3N4 56.05%) was more than that at pH = 7.4 for (ZnFe2O4@mZnO 66.26%) (ZnFe2O4@mZnO-Ox-p-g-C3N4 45.40%) after 72 h.

Synthesis of Cu Single Atoms Supported on Mesoporous Graphitic Carbon Nitride and Their Application in Liquid-Phase Aerobic Oxidation of Cyclohexene

Synthesis of Cu Single Atoms Supported on Mesoporous Graphitic Carbon Nitride and Their Application in Liquid-Phase Aerobic Oxidation of Cyclohexene

Strontium oxide modified mesoporous graphitic carbon nitride/titanium dioxide nanocomposites (SrO-mpg-CN/TiO2) as efficient heterojunction photocatalysts for the degradation of tetracycline in water

We report herein a facile synthesis of a ternary nanocomposite of strontium oxide modified mesoporous graphitic carbon nitride supported titanium dioxide (SrO-mpg-CN/TiO2) as an efficient heterojunction photocatalyst for the degradation of tetracycline (TC) in water. The morphology, optical and textural properties of as-prepared nanocomposites are systematically investigated by various advanced analytical techniques, and the structure-photocatalytic efficiency was related by proposing a plausible mechanism. The photocatalytic performance of SrO-mpg-CN/TiO2 nanocomposites was evaluated in the TC degradation in water by studying several reaction parameters including the catalyst dosage, initial TC concentration, pH and irradiation time. The photocatalytic experiments exhibited that the activity of SrO-mpg-CN/TiO2 nanocomposites for TC degradation was higher than binary SrO-mpg-CNnanocomposites and pristine TiO2. The enhanced photocatalytic activity of SrO-mpg-CN/TiO2 nanocomposites is attributed to the moderator role of SrO for electron transportation in the photocatalysis mechanism, which ensures a high charge mobility, suppresses electron/hole recombination, and improves the redox capacity under UVA irradiation. The detailed optimization studies revealed that the highest TC degradation efficiency of 91.73% was obtained by using 0.1 g/L catalyst dosage and 10 mg/L TC concentration at natural pH of 5.06 for 180 min reaction time under UVA irradiation. Moreover, the scavenging experiments showed that OHads· andO2·-radicals are the dominant species for the TC degradation in water. Moreover, SrO-mpg-CN/TiO2 nanocomposites were reusable up to the five successive runs without a significant drop in their initial activity.

Dual-atom Pt heterogeneous catalyst with excellent catalytic performances for the selective hydrogenation and epoxidation

Atomically monodispersed heterogeneous catalysts with uniform active sites and high atom utilization efficiency are ideal heterogeneous catalytic materials. Designing such type of catalysts, however, remains a formidable challenge. Herein, using a wet-chemical method, we successfully achieved a mesoporous graphitic carbon nitride (mpg-C3N4) supported dual-atom Pt2 catalyst, which exhibited excellent catalytic performance for the highly selective hydrogenation of nitrobenzene to aniline. The conversion of ˃99% is significantly superior to the corresponding values of mpg-C3N4-supported single Pt atoms and ultra-small Pt nanoparticles (~2 nm). First-principles calculations revealed that the excellent and unique catalytic performance of the Pt2 species originates from the facile H2 dissociation induced by the diatomic characteristics of Pt and the easy desorption of the aniline product. The produced Pt2/mpg-C3N4 samples are versatile and can be applied in catalyzing other important reactions, such as the selective hydrogenation of benzaldehyde and the epoxidation of styrene.

Precursor Nuclearity and Ligand Effects in Atomically‐Dispersed Heterogeneous Iron Catalysts for Alkyne Semi‐Hydrogenation

AbstractNanostructuring earth‐abundant metals as single atoms or clusters of controlled size on suitable carriers opens new routes to develop high‐performing heterogeneous catalysts, but resolving speciation trends remains challenging. Here, we investigate the potential of low‐nuclearity iron catalysts in the continuous liquid‐phase semi‐hydrogenation of various alkynes. The activity depends on multiple factors, including the nuclearity and ligand sphere of the metal precursor and their evolution upon interaction with the mesoporous graphitic carbon nitride scaffold. Density functional theory predicts the favorable adsorption of the metal precursors on the scaffold without altering the nuclearity and preserving some ligands. Contrary to previous observations for palladium catalysts, single atoms of iron exhibit higher activity than larger clusters. Atomistic simulations suggest a central role of residual carbonyl species in permitting low‐energy paths over these isolated metal centers.

A molecular approach to the synthesis of platinum-decorated mesoporous graphitic carbon nitride as selective CO2 reduction photocatalyst

Platinum nanoparticles (Pt-NPs) have been directly synthesized through the organometallic approach onto the surface of mesoporous graphitic carbon nitride (mpg-CN) semiconductor with two different metal loadings. Thorough multi-technique characterization reveals a very good dispersion of nanoparticles with a narrow size distribution centered at ca. 2.5 nm, regardless of the metal loading, and composed primarily of platinum metal with a minor contribution of oxidic surface species. Compared to bare mpg-CN, the Pt-NPs decorated materials show improved charge separation properties upon band gap excitation, ascribed to electron extraction by Pt-NPs from the conduction band of mpg-CN, as demonstrated by time-resolved fluorescence measurements. The so-obtained materials show photocatalytic activity for CO2 reduction under both UV and visible light irradiation, with improved selectivity towards highly reduced products such as methanol and methane with respect to the bare semiconductor, which leads to the formation of carbon monoxide as the main product. The obtained results shed light on the pathways that determine selectivity in photocatalytic CO2 conversion, contributing to the development of selective photocatalysts, which is one of the cornerstones in this promising technology for direct solar-to-chemical energy conversion.

Construction of mesoporous C3N4/rGO composite with enhanced visible light photocatalytic activity

A feasible template-free calcination method was carried out to synthesize the hybrid of mesoporous graphitic carbon nitride (mpg-C3N4) and reduced graphene oxide (rGO) with highly efficient photocatalytic ability. The morphology and microstructure of the heterojunction photocatalysts (mpg-C3N4/rGO) were characterized and discussed. The results revealed that the mpg-C3N4/rGO exhibited high surface area 84.974 m2/g and mesoporous morphology, which provides tremendous contact area for rGO sheets. The introduction of rGO led to red-shift of the absorption spectrum and improved the conductive property of the mpg-C3N4/rGO, facilitating the transfer of photo-generated electrons. The formation of heterojunction provided an efficient transfer pathway to separate the photoinduced carriers. The mpg-C3N4/rGO heterojunction exhibited an enhanced visible light-activated degradation of rhodamine B (RhB). The RhB dye was almost removed within 40 min, exhibiting higher photocatalytic efficiency about 5.7 times that of pristine g-C3N4. The synergetic effect of mesporous framework and interface heterojunction contributes to the prominent performance of the photocatalyst.

A selective voltammetric pH sensor using graphitized mesoporous carbon/polyaniline hybrid system

Development of a new pH sensor system, which is simple to prepare, sensitive, selective and workable with low volume, is demanding research in biomedical and environmental studies. In the literature, organic molecules like methylene blue, toluidine blue, hydroquinone, catechol, anthraquinone and polyaniline-based redox probes have been widely used for this purpose. In general, these redox probes have easily interfered with common biochemicals such as dopamine, ascorbic acid, NADH, H2O2, cysteine, hydrazine, and some transition metal ions, etc., and in turn to marked potential and current drifts (pH-false positive response). In this work, a highly redox-active, stable and interference-free redox polymer based on poly(4-chloroaniline) (PANI(4-Cl)) modified graphitized mesoporous carbon (GMC), designated as GMC@PANI(4-Cl), has been prepared using 4-chloroaniline as a monomer in pH 7 phosphate buffer solution. The new redox polymer system showed a distinct redox peak at Eo’= 0.15 V vs Ag/AgCl with a stable voltammetric response. Transmission electron microscope analysis of the redox polymer composite had shown adhesion of black polymeric solid due to polyaniline like the molecular system as a surface layer on the GMC material. The constructed calibration plot was linear in the pH window 2-11 with a slope and regression values − 58 mV pH−1 and 0.9997, respectively. The GMC@PANI(4-Cl) modified electrode showed a sensitive and selective pH monitoring without any interference from the common biochemicals as listed above. As a practical application, pH sensing of commercial pH solutions, undiluted urine and saliva samples were demonstrated. Also, a three-in-one screen-printed carbon modified GMC@PANI(4-Cl) was explored for pH monitoring of a bacterial (E.coli) growth, which showed a comparable response with the conventional pH electrode.

Ternary nanocomposites of mesoporous graphitic carbon nitride/black phosphorus/gold nanoparticles (mpg-CN/BP-Au) for photocatalytic hydrogen evolution and electrochemical sensing of paracetamol

We report herein the fabrication of a novel ternary nanocomposite of mesoporous graphitic carbon nitride/black phosphorus-gold nanoparticles (mpg-CN/BP-Au) and its catalytic performance in the photocatalytic hydrogen evolution reaction (HER) and electrochemical detection of paracetamol. The photocatalytic hydrogen production rate of mpg-CN/BP-Au nanocomposite (1024 µmol g−1 for 8 h) is compared with mpg-CN, mpg-CN/BP and mpg-CN/Au in the presence of triethanolamine (TEOA) as a hole scavenger under the visible light. In addition to the photocatalytic HER application, as-prepared mpg-CN/BP-Au nanocomposite was deposited on modified glassy carbon electrode (mpg-CN/BP-Au/GCE) and for the first time tested for the detection of paracetamol (PA). Under the optimum conditions, linear range of paracetamol detection was found to be in the range of 0.3–120 µM with a detection limit of 0.0425 µM. mpg-CN/BP-Au/GCE provided higher electrocatalytic activity than pristine mpg-CN and all other tested binary nanocomposites. The enhanced photo- and electrochemical activity of mpg-CN/BP-Au/GCE are attributed to formation of heterojunction between BP and mpg-CN materials. Additionally, Au nanoparticles increase the rate of adsorption of mpg-CN/BP due to the excellent electrical properties and spillover effect. We believe that the presented design and catalysis of the ternary nanocomposite will pave a way in many photo- and electrochemical applications.

Role of graphitized mesoporous carbon on solidification and melting characteristics of water for cool thermal storage

Cool thermal energy storage systems (CTES) using phase change materials (PCM) are paramount in the energy management of buildings. This work aims to investigate the role of graphitized mesoporous carbon (GMC) on the thermal storage behavior of water based nanofluid PCM (NFPCM) in a spherical capsule. The NFPCMs exhibit a lower contact angle, indicating a reduction in the nucleation energy barrier. Thermal conductivity of NFPCM shows an enhancement of 36% with the presence of graphitized walls and isotropic nature of GMC. Temperature–time history method is used to evaluate the latent heat of fusion for the NFPCMs and the results are compared with differential scanning calorimetry measurements. Addition of GMC shortens the solidification duration by 6% and reduces the subcooling of NFPCM compared to base PCM. The charging results of NFPCMs demonstrate a cool energy storage of 96% in accelerated mode. The melting rate of NFPCM is expedited at a minimal GMC concentration and melting duration prolongs with further GMC addition. In conclusion, the proposed NFPCMs exhibiting a lower subcooling, improved nucleation behavior and accelerated mode of charging shows great potential for CTES applications.

Continuous Gas–Liquid–Solid Slug Flow for Sustainable Heterogeneously Catalyzed PET-RAFT Polymerization

Gas-liquid-solid (G-L-S) three-phase slug flow provides an efficient pathway to utilize solid catalysts in continuous flow and was adopted in the mesoporous graphite carbon nitride (mpg-C3N4)-catalyzed photoinduced electron/energy transfer reversible addition-fragmentation chain transfer (PET-RAFT) polymerization of methyl methacrylate (MMA) in this work. Kinetic studies and chain extension experiments illustrated the realization of reversible deactivation radical polymerization (RDRP) and the to scale upadvantage of a continuous-flow reactor as compared to its batch counterpart. The light intensity played an important role on the PET-RAFT polymerization. An increasing amount of photocatalyst favored the monomer conversion within a limited range due to higher light blockage, and the monomer conversion reached a stable level at a lower catalyst concentration when higher light power was applied. When compared with fully continuous flow, the G-L-S slug flow was beneficial to the PET-RAFT polymerization due to the intensified swirling strength and narrower velocity field. Decreasing the gas-To-slurry ratio also led to narrower velocity distribution, which favored the polymerization as well. Moreover, the polymerization rates remained stable in multiple recycles, demonstrating that the present G-L-S slug flow was a reliable and easy processing approach for utilizing the solid catalyst.

Mono lacunary phosphomolybdate supported on mesoporous graphitic carbon nitride: An eco-friendly and efficient catalyst for oxidative desulfurization of the model and real fuels

In recent years, one of the most important environmental researchers' subjects has been introduced appropriate and effective methods for desulfurization from fossil fuels and prevent the release of sulfur compounds obtained from combustion into the environment. In this study, sulfur oxidation of refractory organosulfur compounds supported on graphitic carbon nitride (g-C3N4) was examined ‎utilizing‎ a novel catalyst comprising monolacunary phosphomolybdate (PMo11). The optimized reaction ‎conditions, which encompass the loading amount of PMo11 on g-C3N4, the dosage of catalyst, reaction time, ‎reaction temperature, the proportion of O/S, initial DBT ‎concentration, and type of model fuel, have been explored. This catalytic system's superiority has been shown by obtaining 98.6% conversion of DBT in the model fuel and 93.7% sulfur ‎removal from real fuel.

Highly efficient photocatalytic degradation of organic pollutants by mesoporous graphitic carbon nitride bonded with cyano groups

Constructing high-performance visible-light responsive photocatalyst to remediate organic pollutants from wastewater is of great challenge in recent years. In this study, by using SiO2 clusters as a template, mesoporous graphitic carbon nitride nano-clusters (NC MCN) were fabricated as a high-activity photocatalyst. The confined growth of carbon nitride in the presence of SiO2 clusters introduced extra structural defects to the carbon nitride framework including nitrogen vacancies and cyano groups, which was confirmed by employing different characterization analyses. These structural defects created midgap states below the conduction band, which improved light-harvesting efficiency and suppressed electron-hole recombination. Thus, NC MCN showed high photocatalytic activity toward degradation of both tetracycline and rhodamine B under visible light irradiation. Complete degradation of 15 mL solution of 15 ppm tetracycline was achieved in 30 min compared to the bulk catalyst (taking more than 3 h). Furthermore, NC MCN demonstrated high stability after reusing for 8 consecutive photodegradation cycles. The total organic carbon concentration at different reaction time showed a rising and falling trend, which illustrate photodegradation process, i.e. adsorption, photodegradation, and mineralization. By liquid chromatography-mass spectroscopy analysis, the produced intermediates during the tetracycline degradation were proposed, which showed the formation of smaller molecules in just 15 min. The toxicity of the intermediates was analyzed using quantitative structure–activity relationship estimation and the outcomes exhibited that the toxicity of the solution reduced as the reaction time increased. This comprehensive study from photodegradation process to mineralization of TC demonstrated NC MCN as a promising photocatalyst for sustainable treatment of wastewater.

Mesoporous g-C3N4 nanosheets with improved photocatalytic performance for hydrogen evolution

Mesoporous graphitic carbon nitride (g-C3N4) nanosheets are fabricated by ultrasonically exfoliating the bulk g-C3N4 in sulfuric acid aqueous solution. In comparison with the bulk counterpart, the as-prepared g-C3N4 nanosheets have a higher specific surface area, narrower bandgap, better light response and lower charge transfer resistance. Consequently, the mesoporous g-C3N4 nanosheets exhibit a 3.3-fold photocatalytic hydrogen evolution when irradiated with visible light. The improved photocatalytic performance of the g-C3N4 nanosheets is mainly because of the increased specific surface area, abundant mesopores and narrowed bandgap, which would increase the reactive sites, shorten carriers transfer paths and improve their light absorption ability as well.