Exfoliation Strategy Research Articles

Thermal Exfoliation and Phosphorus Doping in Graphitic Carbon Nitride for Efficient Photocatalytic Hydrogen Production.

Photocatalytic H2 evolution has been regarded as a promising technology to alleviate the energy crisis. Designing graphitic carbon nitride materials with a large surface area, short diffusion paths for electrons, and more exposed reactive sites are beneficial for hydrogen evolution. In this study, a facile method was proposed to dope P into a graphitic carbon nitride framework by calcining melamine with 2-aminoethylphosphonic acid. Meanwhile, PCN nanosheets (PCNSs) were obtained through a thermal exfoliation strategy. Under visible light, the PCNS sample displayed a hydrogen evolution rate of 700 μmol·g-1·h-1, which was 43.8-fold higher than that of pure g-C3N4. In addition, the PCNS photocatalyst also displayed good photostability for four consecutive cycles, with a total reaction time of 12 h. Its outstanding photocatalytic performance was attributed to the higher surface area exposing more reactive sites and the enlarged band edge for photoreduction potentials. This work provides a facile strategy to regulate catalytic structures, which may attract great research interest in the field of catalysis.

Efficient fabrication of high-quality graphene via alternating-current co-intercalation and microwave-assisted expansion

To facilitate the transformation of inexpensive and abundant graphite resources into two-dimensional graphene materials with promising applications, the development of efficient, cost-effective, and scalable technologies for large-scale production of high-quality graphene is crucial. Here, we propose an effective electrochemical dual-electrode co-intercalation exfoliation strategy. During the process, precise control of the electrochemical intercalation is achieved by adjusting the working bias and alternating current (AC) cycle, while ensuring the ion insertion rate through gradual voltage escalation. Repeated insertion of cations and anions under AC accelerates the graphite exfoliation. Following complete ion inserting, suitable microwave processing was employed to achieve rapid graphite expansion. Ultimately, ultra-sonication in NMP is employed to achieve final exfoliation between graphite layers. The resulting few-layer graphene (2–3 layers) exhibited minimal defects (ID/IG = 0.0405), low oxygen content (C/O = 44.62), high yield (95.3 %), and excellent conductivity (625 S/cm), enabling its potential commercialization and large-scale application. This outcome also serves as a significant reference for the commercial production of environmentally friendly and cost-effective graphene.

Liquid-Metal-Based Spin-Coating Exfoliation for Atomically Thin Metal Oxide Synthesis.

Two-dimensional (2D) semiconductors possess exceptional electronic, optical, and magnetic properties, making them highly desirable for widespread applications. However, conventional mechanical exfoliation and epitaxial growth methods are insufficient in meeting the demand for atomically thin films covering large areas while maintaining high quality. Herein, leveraging liquid metal oxidation reaction, we propose a motorized spin-coating exfoliation strategy to efficiently produce large-area 2D metal oxide (2DMO) semiconductors with high crystallinity, atomically thin thickness, and flat surfaces on diverse substrates. Moreover, we realized a 2D gallium oxide-based deep ultraviolet solar-blind photodetector featuring a metal-semiconductor-metal structure, showcasing high responsivity (8.24 A W-1) at 254 nm and excellent sensitivity (4.3 × 1012 cm Hz1/2 W-1). This novel liquid-metal-based spin-coating exfoliation strategy offers great potential for synthesizing atomically thin 2D semiconductors, opening new avenues for future functional electronic and optical applications.

UV to NIR Broadband Flexible Photodetector Based on Solution‐Processed MoS2/PDPP3T Inorganic–Organic Hybrid Heterostructures

AbstractMolybdenum disulfide (MoS2) is a 2D material with excellent electrical and optical properties, and developing a universal technology for the preparation of high‐performance MoS2‐based photodetector is extremely desirable. Here, a UV to NIR broadband flexible photodetector based on MoS2/(PDPP3T) inorganic–organic hybrid heterostructures is reported. In the experiment, high crystalline 2H‐phase few‐layer MoS2 nanoflakes are first prepared by optimized electrochemical intercalation of tetraheptylammonium cation (THA+) and ultrasound‐assisted exfoliation strategy. Thereafter, a narrow bandgap organic semiconductor PDPP3T is introduced to construct the MoS2/Poly(diketopyrrolopyrrolothiophrn) (PDPP3T) heterojunction. Experimental results reveal that the photodetector can have broadband photo response from 380 to 980 nm. Meanwhile, excellent responsivities and detectivity of 12.4 mA W−1, 2.2 × 1010 Jones at 380 nm and 0.1 mA W−1 and 5 × 108 Jones at 980 nm are achieved, which are ≈10 (UV band)/100 (NIR band) times high than that obtained on the pure MoS2‐based detector. Moreover, the flexibility of the device is investigated by conformal covering the device on a curved surface (R = 5 and 2.5 mm), it shows that the photo response remains almost the same as that measured on the planar substrate, indicating the possible application in the wearable electronics.

In-situ exfoliation of hexagonal boron nitride during the forced flow of highly elastic polylactide to fabricate electrospun fibrous film with high thermal conductivity and low dielectric loss

Boron nitride nanosheets (BNNS) have promising applications in thermal management materials, due to their high thermal conductivity and low dielectric loss. However, it is still challenging to fabricate BNNS with large lateral size and structural integrity via solvent-free methods. Here, we report a novel processing method for in-situ exfoliation of hexagonal boron nitride (h-BN) to fabricate BNNS with an average lateral size of 1.45 μm, average thickness of 4.88 nm and few lattice defects during the forced flow of polylactide (PLA) in a highly elastic state. We further fabricate flexible and bio-degradable PLA/BNNS electrospun fibrous film for electronic devices to replace petroleum-based composites. The PLA/BNNS fibrous film exhibits an in-plane thermal conductivity of 4.9 W/(m·K) at the BNNS loading of 20 wt%. Moreover, the fibrous film also has a low dielectric loss (0.007 at 1 kHz) and good electrical insulation. The in-situ exfoliation strategy is simple, economical and environmentally friendly, providing an effective route to design thermal management materials with high thermal conductivity and low dielectric loss in the future of electronic devices.

In situ construction of efficient electromagnetic function Graphene/PES composites based on liquid phase exfoliation strategy

Although graphene nanosheets (GNs) with huge specific surface area and exceptional electrical properties exhibit attractive practical prospect in the realm of electromagnetic function materials, how to optimize the distribution states of GNs in matrix is still a challenge. In this work, the suspension of GNs was prepared directly via an efficient liquid-phase exfoliation (LPE) process in N-octyl-2-pyrrolidone (NOP). Thanks to the dissolution of polyether sulfone (PES) in NMP and NOP solvent, the GNs/PES composites were in-situ prepared via a facile solution blending in combination with evaporation process. The “function units” of the mesoscopic micro-cluster structure assembled by GNs during the solvent evaporation process contribute to optimized impedance matching characteristics and loss capabilities as well as excellent electromagnetic wave (EMW) absorbing performance of the as-constructed GNs/PES electromagnetic composites. Particularly, the as-prepared sample G-P-9 with a graphene content of as low as 9.0 wt% exhibits outstanding EMW absorbing performance in the whole ranges of tested frequency (8.2–12.4 GHz) and temperature (293–453 K) with a minimum reflection loss (RL) of −52.7 dB. Besides, the in-situ self-assemble GNs/single-walled carbon nanotubes (GNs/SWCNT) film with pre-constructed three-dimensional interpenetrating conductive network exhibits excellent electromagnetic interference (EMI) shielding effectiveness (SE) of about 5.1 × 104 dB cm2 g−1. The present approach would be applicable to construct high-performance electromagnetic functional materials and broaden the application prospect of high-integrity graphene nanosheets.

2D Ferromagnetic M3GeTe2 (M = Ni/Fe) for Boosting Intermediates Adsorption toward Faster Water Oxidation.

In this work, 2D ferromagnetic M3GeTe2 (MGT, M = Ni/Fe) nanosheets with rich atomic Te vacancies (2D-MGTv) are demonstrated as efficient OER electrocatalyst via a general mechanical exfoliation strategy. X-ray absorption spectra (XAS) and scanning transmission electron microscope (STEM) results validate the dominant presence of metal-O moieties and rich Te vacancies, respectively. The formed Te vacancies are active for the adsorption of OH* and O* species while the metal-O moieties promote the O* and OOH* adsorption, contributing synergistically to the faster oxygen evolution kinetics. Consequently, 2D-Ni3GeTe2v exhibits superior OER activity with only 370mV overpotential to reach the current density of 100mA cm-2 and turnover frequency (TOF) value of 101.6 s-1 at the overpotential of 200mV in alkaline media. Furthermore, a 2D-Ni3GeTe2v-based anion-exchange membrane (AEM) water electrolysis cell (1 cm2) delivers a current density of 1.02 and 1.32 A cm-2 at the voltage of 3V feeding with 0.1 and 1m KOH solution, respectively. The demonstrated metal-O coordination with abundant atomic vacancies for ferromagnetic M3GeTe2 and the easily extended preparation strategy would enlighten the rational design and fabrication of other ferromagnetic materials for wider electrocatalytic applications.

Thiol ligand-mediated exfoliation of bulk sulfur to nanosheets and nanodots: applications in antibacterial activity.

Reducing bulk materials to layers or dots results in profound alterations in their physiochemical and optoelectronic properties, leading to a wide array of applications, spanning from device manufacturing to biomedicine. In this regard, the preparation of sulfur nanomaterials has garnered significant attention due to their low toxicity. Traditional methods for sulfur nanomaterial synthesis often involve harsh reaction conditions, leaving a gap for convenient approaches to create nanomaterials, such as nanosheets (NSs) and nanodots (NDs). Herein, the mechanical exfoliation of bulk sulfur using a surfactant thiol ligand with probe sonication is reported, making a unique contribution to existing methods. In the reported method, the thiol group binds to sulfur surfaces, facilitating exfoliation and stabilization, while the hydrophilic ends provide functional groups for exfoliated nanomaterials. Exfoliation can yield either nanosheets or nanodots, depending on the thiol ligand and exfoliation time. This approach offers the opportunity to exfoliate bulk sulfur using bioactive thiol ligands. With this goal in mind, bulk sulfur was exfoliated with 4-mercaptophenylboronic acid (BA) to target Gram-positive bacteria. This innovative exfoliation strategy of bulk sulfur using thiol ligands holds immense promise for synthesizing functionalized sulfur nanomaterials with wide-ranging applications, particularly in biomedicine.

Novel 2D MXene Cobalt Ferrite (CoF@Ti3C2) Composite: A Promising Photothermal Anticancer In Vitro Study.

In search of materials with superior capability of light-to-heat (photothermal) conversion, biocompatibility, and confinement of active photothermal materials within the cells, novel magnetic MXene-based nanocomposites are found to possess all of these criteria. The CoF@Ti3C2 composite is fabricated by a simple two-step method, including an exfoliation strategy followed by sonochemical method. MXene composite has been modified with polyvinylpyrrolidone (PVP) to improve the stability in physiological conditions. The synthesized composite was characterized with multiple analytical tools. In vitro photothermal conversion efficiency of composite was determined by the time constant method and achieved η = 34.2% with an NIR 808 nm laser. In vitro, cytotoxicity studies conducted on human malignant melanoma (Ht144) and cells validated the photothermal property of the CoF@Ti3C2-PVP composite in the presence of an NIR laser (808 nm, 1.0 W cm-2), with significantly increased cytotoxicity. Calculated IC50 values were 86 μg/mL with laser, compared to 226 μg/mL without the presence of NIR laser. Microscopic results demonstrated increased apoptosis in the presence of NIR laser. Additionally, hemolysis assay confirmed biocompatibility of CoF@Ti3C2-PVP composite for intravenous applications at the IC50 concentration. The research described in this work expands the potential applications of MXene-based nanoplatforms in the biomedical field, particularly in photothermal therapy (PTT). Furthermore, the addition of cobalt ferrite serves as a magnetic nanocomposite, which eventually helps to confine therapeutic photothermal materials inside the cells, provides enhanced photothermal conversion efficiency, and creates externally controlled theranostic nanoplatforms for cancer therapy.

Tandem molecular intercalation exfoliated TiSe2 nanosheets for enhanced sodium-ion storage

Although layered transition metal dichalcogenides (TMDs) possess relatively high electrical and moderate ionic conductivities, their inclination to stack layered structure inevitably leads to a sluggish ion diffusion and limited cyclic life when used as anode materials. Therefore, the realization of few-layered structure with widened layer distance would facilitate the ion migration and thus help TMDs to gain enhanced performance. In this study, tandem molecular intercalation method was applied to fabricate few-layered TiSe2 nanosheets (ef-TiSe2) with pronounced expanded layer spacing (∼10 Å) using propylamine and hexylamine as intercalators. Density functional theory calculations disclose that there is a continuous charge accumulation between the TiSe2 interlayers, which enables Na+ to exhibit a strong adsorption tendency, thus forming a certain Coulombic force. Furthermore, the lowest Na+ diffusion barrier between interlayers guarantees TiSe2 to achieve rapid reaction kinetics. The effective exfoliation strategy renders the obtained ef-TiSe2 rich exposed reaction active sites, sufficient electrolyte penetration, shortened diffusion distance of ion/electron, suppressed stress caused by structural changes, and increased effective utilization of the material. Interestingly, compared with bulk TiSe2, few-layered ef-TiSe2 nanosheets exhibited a shorter activation cycling period, lower reaction polarization, and expedited reaction kinetics, therefore providing a high specific capacity (417 mA h g−1 at 1 A g−1) and cyclic stability (with a high-capacity retention of 95.36 % after 2000 cycles at 5 A g−1). In addition, the combined mechanism of intercalation and conversion in TiSe2 was closely elucidated by in situ X-ray diffraction and in situ electrochemical impedance spectroscopy.

2D-Material-Assisted GaN Growth on GaN Template by MOCVD and Its Exfoliation Strategy.

The production of freestanding membranes using two-dimensional (2D) materials often involves techniques such as van der Waals (vdW) epitaxy, quasi-vdW epitaxy, and remote epitaxy. However, a challenge arises when attempting to manufacture freestanding GaN by using these 2D-material-assisted growth techniques. The issue lies in securing stability, as high-temperature growth conditions under metal-organic chemical vapor deposition (MOCVD) can cause damage to the 2D materials due to GaN decomposition of the substrate. Even when GaN is successfully grown using this method, damage to the 2D material leads to direct bonding with the substrate, making the exfoliation of the grown GaN nearly impossible. This study introduces an approach for GaN growth and exfoliation on 2D material/GaN templates. First, graphene and hexagonal boron nitride (h-BN) were transferred onto the GaN template, creating stable conditions under high temperatures and various gases in MOCVD. GaN was grown in a two-step process at 750 and 900 °C, ensuring exfoliation in cases where the 2D materials remained intact. Essentially, while it is challenging to grow GaN on 2D material/GaN using only MOCVD, this study demonstrates that with effective protection of the 2D material, the grown GaN can endure high temperatures and still be exfoliated. Furthermore, these results support that vdW epitaxy and remote epitaxy principle are not only possible with specific equipment but also applicable generally.

Highly Efficient Liquid-Phase Exfoliation of Layered Perovskite-like Titanates HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd) into Nanosheets

Nanosheets of layered perovskite-like oxides attract researchers as building blocks for the creation of a wide range of demanded nanomaterials. However, Ruddlesden–Popper phases are difficult to separate into nanosheets quantitatively via the conventional liquid-phase exfoliation procedure in aqueous solutions of bulky organic bases. The present study has considered systematically a relatively novel and efficient approach to a high-yield preparation of concentrated suspensions of perovskite nanosheets. For this, the Ruddlesden–Popper titanates HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd) have been intercalated by n-alkylamines with various chain lengths, exposed to sonication in aqueous tetrabutylammonium hydroxide (TBAOH) and centrifuged to separate the nanosheet-containing supernatant. The experiments included variations of a wide range of conditions, which allowed for the achievement of impressive nanosheet concentrations in suspensions up to 2.1 g/L and yields up to 95%. The latter were found to strongly depend on the length of intercalated n-alkylamines. Despite the less expanded interlayer space, the titanates modified with short-chain amines demonstrated a much higher completeness of liquid-phase exfoliation as compared to those with long-chain ones. It was also shown that the exfoliation efficiency depends more on the sample stirring time in the TBAOH solution than on the sonication duration. Analysis of the titanate nanosheets obtained by means of dynamic light scattering, electron and atomic force microscopy revealed their lateral sizes of 30–250 nm and thickness of 2–4 nm. The investigated exfoliation strategy appears to be convenient for the high-yield production of perovskite nanosheet-based materials for photocatalytic hydrogen production, environmental remediation and other applications.

Modified Molten Salt Assisted Exfoliation of Large‐Size 2D Materials

Abstract2D materials hold great promise for numerous applications, and the physical properties of individual 2D materials depend strongly on their thickness and lateral size. Currently, there is a lack of a straightforward method to produce 2D materials with both high‐quality and ultra‐high aspect ratios. Herein, a modified molten salt‐assisted exfoliation (MMSAE) strategy is proposed to prepare high‐quality 2D materials with large sizes and controllable thickness. The MMSAE approach involves using high‐frequency disturbance to create a shear force that peels off the layers of the intercalated material (e.g., graphene, MoS2, WS2, and clays), resulting in the successful and efficient exfoliation of 2D material. Taking h‐BN for example, the MMSAE approach achieves the preparation of 2D h‐BN with an average lateral size of 6.30 µm, thickness of 2.34 nm, and a high aspect ratio of 2692.

Quartz Nonadherent and Clean Exfoliation of the Heteroatom-Doped Bulk Carbon Nanotubes Array.

Vertically aligned carbon nanotubes array offers unique properties for various applications. Detaching them from the growth substrate, while preserving their vertical structure, is essential. Quartz, a cost-effective alternative to silicon wafers and metal-based substrates, can serve as both a reaction chamber and a growth substrate. However, the strong adhesive interaction with the quartz substrate remains an obstacle for further applications. Herein, we presented a simple and well-controlled exfoliation strategy assisted by the introduction of heteroatoms at root ends of a carbon nanotubes array. This strategy forms lower surface polarity of the carbon fragment to significantly reduce adhesion to the quartz substrate, which contributes to the effortless exfoliation. Furthermore, this scalable approach enables potential mass production on recyclable quartz substrates, enhancing the cost-effectiveness and efficiency. This work can establish a solid foundation for cost-competitive carbon nanotube-based technologies, offering a promising avenue for their widespread applications.

Two-dimensional perovskite NdNb2O7 for high-performance UV photodetectors by a general exfoliation and assembly strategy

Two-dimensional (2D) oxide perovskites show great promise as candidates for future optoelectronic devices. For the first time, we have successfully exfoliated 2D perovskite NdNb2O7 (NNO) nanosheets by a solid-state calcination and liquid-phase exfoliation method. The individual NNO nanosheet photodetector (PD) demonstrates outstanding performance in detecting UV light (260 nm, 3 V), including high responsivity (62 AW−1), high detectivity (6.7 *1012 Jones), high spectral selectivity (R260/R400= 9000), fast response speed (0.1/7.8 ms) and long-term stability. Furthermore, through a simple interface self-assembly technique, we have successfully achieved orderly and flat films of NNO nanosheets. The resulting film exhibits high transparency (>75 %) in the visible light range. The NNO film device demonstrates excellent performance after undergoing numerous bending tests. This work not only presents a new candidate for high-performance and high-stability UV photodetectors but also introduces a general exfoliation and assembly strategy.

Facet-dependent adsorption of heavy metal ions on Janus clay nanosheets

Understanding the facet-dependent adsorption behavior and mechanism of heavy metal ions (HMs) on two-dimensional (2D) Janus nanoclays has important implications for the environment and ecosystem but still remains elusive. Herein, ultrathin Janus serpentene (2D serpentine) nanosheets were fabricated via a facile, nontoxic, and residue-free exfoliation strategy. Fabricated serpentene nanosheets exhibited promising Cd(II) and Pb(II) adsorption capacities due to their high surface areas and abundant active sites, approximately four times higher than those of bulk serpentine powders. Interestingly, Cd(II) and Pb(II) adsorption on serpentene nanosheets exhibited a facet-dependent feature, with the adsorption amount on the Mg–OH plane considerably higher than that on the Si–O plane. This facet-dependent adsorption behavior was mainly attributed to the difference in the interaction mechanisms of HMs with the Mg–OH (monodentate inner-sphere complexation) and Si–O (outer-sphere complexation) planes, which was further confirmed via density functional theory calculations. The Cd(II) adsorption on serpentene nanosheets was limited by strong kinetic restrictions (e.g., stronger electrostatic repulsion and higher dehydration energy barrier than that for Pb(II) adsorption). This study provides insights into the facet-dependent adsorption mechanisms of HMs on Janus serpentene nanosheets, which can be extended to other nanoclays used in wastewater treatment and many environmental processes.

Facile synthesis of a Z-scheme CeO2/C3N4 heterojunction with enhanced charge transfer for CO2 photoreduction

Using solar energy to convert CO2 into value-added fuel is crucial for the goal of global carbon neutrality. Effective separation of photogenerated charges is important for improving photocatalytic CO2 reduction efficiency. Herein, we report a facile in situ exfoliation and conversion strategy to synthesize a novel CeO2/C3N4 heterostructure by uniformly distributing CeO2 nanoparticles onto ultrathin porous C3N4 nanosheets. The ultrathin porous structure of C3N4 not only increases the specific surface area to provide more active sites but also effectively shortens the migration distance of photogenerated electron holes to avoid their recombination. In addition, the well-dispersed CeO2 on C3N4 shows an intimate interface contact, which allows more charges to be transferred through the increased interface surface area. The as-synthesized CeO2/C3N4 heterojunction with well-matched band gaps and a Z-scheme structure prolongs the lifetime of photo-induced charge carriers and maximizes the redox ability of the photocatalyst. Without a noble metal cocatalyst or a sacrificial agent, the CO2 photoreduction performance of the CeO2/C3N4 heterojunction is approximately 5-fold enhanced compared with that of bulk C3N4. This study provides a facile strategy for the design and practical application of direct Z-scheme pho-tocatalysts for sustainable energy conversion.

Efficient photocatalytic water disinfection by a novel BP/BiOBr S-scheme heterojunction photocatalyst

With the ever-growing threat posed by pathogenic microorganisms, the development of high-performance photocatalysts for energy-efficient and rapid water disinfection is urgently required. In this study, an S-scheme heterojunction involving black phosphorus (BP) and bismuth oxybromide (BiOBr) is designed by a facile exfoliation strategy. The BP/BiOBr with 0.75% of BP (0.75 %BP/BiOBr) exhibits an outstanding photocatalytic disinfection activity, with the total 7 log killing of E. coli cells in only 7.5 min under visible-light illumination, which is 2 times higher than that of pure BiOBr. And the similar performance was observed for the tap water and river water under real sunlight. The enhanced disinfection efficiency of BP/BiOBr arises from the high yield of the ·O2− and ·OH resulting from the formation of S-scheme heterojunction. Then the ·O2− and ·OH damaged the cell membrane of the bacterial, leading to their death finally. This research sheds lights on the design and application of S-scheme heterojunction photocatalysts in water disinfection.

High‐Yield Exfoliation of Large MXene with Flake Sizes over 10 µm Using Edge‐Anchored Carbon Nanotubes

AbstractThe exceptional properties of 2D transition metal carbides and nitrides (MXene) have led to numerous promising applications. However, the performance of MXene is often dependent on the size of the flakes, and obtaining large‐sized, high‐quality MXene flakes remains challenging. Herein, a carbon nanotube (CNT)‐assisted exfoliation strategy is introduced, which significantly improves the yield of large‐flake MXene while entirely transforming the centrifugation residues into small‐flake MXene, resulting in waste‐free synthesis of MXene. The average size of the obtained MXene flakes can reach over 10 and 0.7 µm for the two populations, respectively. Additionally, the capacitive performance of MXene can be greatly enhanced with a small amount of CNTs. As a proof of concept, a planar interdigital micro‐supercapacitor with heterogeneous layers assembled by large‐ and small‐flake MXene simultaneously exhibits outstanding synergistic enhancement in volumetric capacitance (1072 F cm⁻3) and energy density (53.5 mWh cm⁻3). This CNT‐assisted method provides explicit directions for achieving the ideal utilization of MXene, improving the yield of large flakes while making judicious use of waste, to meet specific application needs.

Easy three steps gC3N4 exfoliation for excellent photocatalytic activity – An in-depth comparison with conventional approaches

Producing an ultrathin nanostructure through exfoliation of carbon nitride (gC3N4) significantly enhances the photoactivity of the material. However, the influence of the exfoliation method on the properties and photocatalytic activity of gC3N4 nanosheets is still poorly understood. In this study, conventional methods such as thermal, chemical and ultrasonic exfoliation of gC3N4 nanosheets have been compared with a three-step exfoliation method. The three-step exfoliation strategy allows the control of the microstructure, light absorption property, morphology and visible light photoactivity of gC3N4 nanosheets. Products show a superior photocatalytic efficiency under simulated sunlight compared to gC3N4 nanosheets obtained with conventional exfoliation methods. Degradation kinetics of this material are also superior. gC3N4 nanosheets prepared by three-step exfoliation exhibit a high specific surface area, optimal band gap energy structure, higher electron density and more efficient charge separation than products of conventional exfoliation methods. This new three-step exfoliation strategy is an easy way for obtaining high performance gC3N4 nanosheets for water purification.