Visible Light Photoactivity Research Articles

Sunlight-driven photocatalytic mineralization of antibiotic chemical and selected enteric bacteria in water via zinc tungstate-imprinted kaolinite

ABSTRACT This study reports the synthesis of sunlight-active zinc oxide-tungstate-kaolinite photocatalytic composite prepared via a green process (solvent-free mechano-thermal process) at an optimum temperature of 500°C for 1 h in a furnace. Electron Paramagnetic Resonance (EPR) study suggests the presence of W5+ defect states in the prepared photocatalytic composite (ZnWK-5), which is responsible for its photoactivity in visible light. Results from further analysis show that hole (h+) and superoxide radical ( . O2 −) are the major contributors to the photocatalytic efficiency of ZnWK-5 photocatalytic composite. This photocatalytic composite was used to treat water containing an antibiotic chemical-ampicillin (AMP) under sunlight. Mass spectrometry analysis of the treated water suggests that the mechanism of photodegradation of AMP is via several bond and ring cleavages, including amide bond, phenyl ring, and β-lactam ring cleavages. These cleavage reactions were followed by subsequent mineralization of ca. 98% after 5 h without the formation of toxic products. The introduction of phosphate and carbonate anions had a serious negative impact on the photocatalytic activity of the composite. However, the photocatalytic composite completely disinfected water contaminated with gram-(−ve) and gram-(+ve) bacteria. Even after five re-use cycles, the photocatalytic composite maintained a 90% photodegradation efficiency of ampicillin in water.

Addressing solar photochemistry durability with an amorphous nickel antimonate photoanode

Renewable generation of fuels using solar energy is a promising technology whose deployment hinges on the discovery of materials with a combination of durability and solar-to-chemical conversion efficiency that has yet to be demonstrated. Stable operation of photoanodes has been demonstrated with wide-gap semiconductors, as well as protected visible gap semiconductors. Visible photoresponse from electrochemically stable materials is quite rare. In this paper, we report the high-throughput discovery of an amorphous Ni-Sb (1:1) oxide photoanode that meets the requirements of operational stability, visible photoresponse, and appreciable photovoltage. X-ray absorption characterization of Ni and Sb establishes a structural connection to rutile NiSb 2 O 6 , guiding electronic structure characterization via X-ray photoelectron experiments and density functional theory. This amorphous photoanode opens avenues for photoelectrode development due to the lack of crystal anisotropy combined with its operational stability, which mitigates the formation of an interphase that disrupts the semiconductor-electrolyte junction. • High-throughput experiments enable the discovery of an amorphous Ni-Sb photoanode • Favorable Pourbaix energetics and amorphous surface provide excellent durability • The broad spectral response stands in contrast to end members Sb 2 O 5 and NiO • Electronic and chemical structure characterization pave the way for future study Harvesting solar energy to sustainably synthesize fuels requires the identification of materials that can operate durably for many years. Inspired by the corrosion resistance of amorphous oxides, Zhou et al. report an amorphous nickel antimonate with visible light photoactivity and lower corrosion than analogous materials, paving a pathway for further technology development.

Enhanced visible light photoactivity of polymeric g-C3N4 by twice exfoliation in the degradation of acetaminophen and ibuprofen

Enhanced visible light photoactivity of polymeric g-C3N4 by twice exfoliation in the degradation of acetaminophen and ibuprofen

Breaking the Limitation of Elevated Coulomb Interaction in Crystalline Carbon Nitride for Visible and Near-Infrared Light Photoactivity.

Most near‐infrared (NIR) light‐responsive photocatalysts inevitably suffer from low charge separation due to the elevated Coulomb interaction between electrons and holes. Here, an n‐type doping strategy of alkaline earth metal ions is proposed in crystalline K+ implanted polymeric carbon nitride (KCN) for visible and NIR photoactivity. The n‐type doping significantly increases the electron densities and activates the n→π* electron transitions, producing NIR light absorption. In addition, the more localized valence band (VB) and the regulation of carrier effective mass and band decomposed charge density, as well as the improved conductivity by 1–2 orders of magnitude facilitate the charge transfer and separation. The proposed n‐type doping strategy improves the carrier mobility and conductivity, activates the n→π* electron transitions for NIR light absorption, and breaks the limitation of poor charge separation caused by the elevated Coulomb interaction.

The application of modified nano-TiO2 photocatalyst for wastewater treatment: A review

ABSTRACT Because of the ever-growing world population and the burgeoning of economic advancements, solving both environmental and energy-driven challenges are of prime concern. In the view of the current scenario, photocatalyst as an environmentally friendly method has rapidly emerged due to its prominent function in the conversion of solar energy for overcoming two aforementioned serious challenges. Recently, numerous attempts have been carried out for enhancing the visible-light photoactivity by application of TiO2 as photocatalyst because of its extensive scope of employment in both environmental-related and energy regions. Nevertheless, the photocatalytic performance of TiO2 under visible-light illumination is seriously restricted by the absorption edge in the ultra-violet range and the rapid electron–hole recombination. Extensive research has been dedicated to bypassing the shortcomings of titanium dioxide and hence improving its photoactivity under visible light. To be more specific, some approaches for modification of TiO2 properties include tetragonal BaTiO3 nanoparticles, ultrasound-assisted preparation of rGO/TiO2 nanocomposite, BaTiO3/ZnO heterostructured photocatalyst, Sol pH-induced ZnO-TiO2 multi-phase composite, BaTiO3/g-C3N4 heterojunction, TiO2-zeolite nanocomposite, etc., were explored and developed. Moreover, in this review paper, the authors briefly evaluated various nano-TiO2 synthesis methods, such as sol-gel, hydrothermal, solvothermal, and mixed ones. Despite the excellent achievements and the improvements in this area, the probability of nano-TiO2 modification for highly efficacious photocatalyst systems has not been completely explored and its commercialisation still is problematic. As a result, still, intensive research efforts require to effectively overcome those challenges for reaching a bright future in the wastewater treatment process with minimum environmental adverse effects.

Enhanced photo-fenton and photoelectrochemical activities in nitrogen doped brownmillerite KBiFe2O5

Visible-light-driven photo-fenton-like catalytic activity and photoelectrochemical (PEC) performance of nitrogen-doped brownmillerite KBiFe2O5 (KBFO) are investigated. The effective optical bandgap of KBFO reduces from 1.67 to 1.60 eV post N-doping, enabling both enhancement of visible light absorption and photoactivity. The photo-fenton activity of KBFO and N-doped KBFO samples were analysed by degrading effluents like Methylene Blue (MB), Bisphenol-A (BPA) and antibiotics such as Norfloxacin (NOX) and Doxycycline (DOX). 20 mmol of Nitrogen-doped KBFO (20N-KBFO) exhibits enhanced catalytic activity while degrading MB. 20N-KBFO sample is further tested for degradation of Bisphenol-A and antibiotics in the presence of H2O2 and chelating agent L-cysteine. Under optimum conditions, MB, BPA, and NOX, and DOX are degraded by 99.5% (0.042 min-1), 83% (0.016 min-1), 72% (0.011 min-1) and 95% (0.026 min-1) of its initial concentration respectively. Photocurrent density of 20N-KBFO improves to 8.83 mA/cm2 from 4.31 mA/cm2 for pure KBFO. Photocatalytic and photoelectrochemical (PEC) properties of N-doped KBFO make it a promising candidate for energy and environmental applications.

Rationally designed tetra (4-carboxyphenyl) porphyrin/graphene quantum dots/bismuth molybdate Z-scheme heterojunction for tetracycline degradation and Cr(VI) reduction: Performance, mechanism, intermediate toxicity appraisement

Constructing novel Z-scheme heterojunctions is an effective strategy for obtaining high-performance photocatalysts. Herein, tetra (4-carboxyphenyl) porphyrin (TCPP) and graphene quantum dots (GQDs) were loaded on the surface of Bi2MoO6 (BMO) to fabricate novel Z-scheme heterojunctions of TCPP/G/BMO. Especially, TCPP/G/BMO-2 showed an exceptional visible-light photoactivity for tetracycline (TC) degradation (81.0%, 40 min) and Cr(VI) reduction (90.7%, 60 min), respectively by 2.38 folds and 2.96 folds enhancement compared to sole Bi2MoO6. The substantial enhancement of activity is attributed to the synergy effect of the Z-scheme charge transfer mechanism and the improved light absorption. The degradation pathways of TC were inferred by determining the generated intermediates using high performance liquid chromatography-mass spectrometry (HPLC-MS), and the toxicity of the transformation products was assessed by Toxicity Estimation Software Tool (T.E.S.T). Overall, on the basis of trapping experiments and electron spin resonance spectra (ESR) analysis, the photocatalytic mechanisms of Cr(VI) reduction and TC degradation by the TCPP/G/BMO Z-scheme heterojunction was proposed. This work indicates TCPP/G/BMO could be a promising photocatalyst for wastewater treatment.

Facile Synthesis of Porous g-C3N4 with Enhanced Visible-Light Photoactivity.

Porous graphitic carbon nitride (g-C3N4) was prepared by dicyandiamide and urea via the pyrolysis method, which possessed enhanced visible-light-driven photocatalytic performance. Its surface area was increased from 17.12 to 48.00 m2/g. The porous structure not only enhanced the light capture capacity, but also accelerated the mass transfer ability. The Di (Dicyandiamide)/Ur (Urea) composite possessed better photocatalytic activity for Rhodamine B in visible light than that of g-C3N4. Moreover, the Di/Ur-4:5 composite showed the best photoactivity, which was almost 5.8 times that of g-C3N4. The enhanced photocatalytic activity showed that holes and superoxide radical played a key role in the process of photodegradation, which was ascribed to the enhanced separation of photogenerated carriers. The efficient separation of photogenerated electron-hole pairs may be owing to the higher surface area, O dopant, and pore volumes, which can not only improve the trapping opportunities of charge carriers but also the retarded charge carrier recombination. Therefore, it is expected that the composite would be a promising candidate material for organic pollutant degradation.

Degradation of Tetracycline on SiO2-TiO2-C Aerogel Photocatalysts under Visible Light.

SiO2-TiO2-C aerogel photocatalysts with different carbon loadings were synthesized by using sol-gel chemistry. The anatase crystal and nonmetal carbon dopant were introduced during the sol preparation and formed by hydrothermal treatment, which can simultaneously enhance the adsorption ability and visible light photo-activity. A high surface area (759 g cm−3) SiO2-TiO2-C aerogel composite can remove up to 80% tetracycline hydrochloride within 180 min under visible light. The characterization of the gel structures shows that the homogeneous dispersion of O, Si, Ti and C in the skeleton, indicating that hydrothermal synthesis could provide a very feasible way for the preparation of composite materials. n(C):n(Ti) molar ratio of 3.5 gives the best catalytic performance of the hybrid aerogel, and the cyclic test still confirms over 60% degradation activity after seven use cycles. All catalysis reaction followed the pseudo-first-order rate reaction with high correlation coefficient. The electrons and holes in the compound could be effectively restrained with doping proper amount of C, and ESR results indicate that the oxidation process was dominated by the hydroxyl radical (•OH) and superoxide radical (•O2−) generated in the system.

One-step synthesis of F-TiO2/g-C3N4 heterojunction as highly efficient visible-light-active catalysts for tetrabromobisphenol A and sulfamethazine degradation

In order to achieve excellent visible light photoactivity of TiO2, it is still urgently required to extend their optical absorption ability and improve the potential of charge separation and migration. Here we synthesized highly efficient visible-light-active catalysts F-TiO2/g-C3N4 via a one-step-calcination method. Due to the synergic effect of ≡Ti−F, ≡Ti:F−H and the heterojunction, the obtained catalysts possess promising properties as highly efficient separation and migration of photoelectron-hole pairs. The prepared F-TiO2/g-C3N4 heterojunction can be successfully applied to degrade the widely used flame retardants and antibiotics. More than 95% of tetrabromobisphenol A (TBBPA) was decomposed after light illumination for 120 min, and 98% of sulfamethazine (SMZ) was degraded for 60 min by F-TiO2/g-C3N4. Furthermore, a reasonable catalytic mechanism for the F-TiO2/g-C3N4 catalysts was proposed. It could be seen that the active species •O2−, •OH, and h+ played important roles in the photocatalytic process under visible light illumination.

Shed light on defect induced enhanced visible-light photocatalysis activity of rutile TiO2 nanoparticles: effects of annealing on blue-gray to light–gray transition

Preparation of the defective TiO2 nanoparticles (NPs) have been recently in particular interest for its outstanding applications in visible-light active photocatalysis. In order to make TiO2 visible-light absorber, optical band gap should be modified especially via introducing structural defects like oxygen vacancies as an effective pathway. In this research, we prepared defective rutile TiO2 NPs with highly efficient photocatalytic activity under visible light. The NPs were synthesized by electric arc discharge in water as a cost-effective and environmentally friendly method with capability of defect formation which followed by heat treatment. The photocatalytic activity improvement mechanisms based on oxygen vacancies were supported by TEM, XPS, XRD, PL and optical spectroscopy characterizations. Spherical TiO2 NPs with average size of 23, 28, 38, and 50 nm were obtained for pristine, and annealed samples at 300, 500 and 700 °C respectively. The optical band gaps of NPs decreased from 2.9 to 2.0 eV with annealing temperature, and a concurrent color change from blue-gray to light-gray. The XPS results confirm the presence of vacant oxygen and surface OH defects in all TiO2 samples. The results reveal that concentration of surface defects and mostly the oxygen vacancies play a crucial role in visible light photoactivity of gray TiO2 nanostructures. In the synthesized TiO2 NPs, the sample with the lowest concentration of non-lattice oxygen exhibit better degradation efficiency than other samples. The results provide a flexible method for synthesis of defective rutile TiO2 as a highly efficient visible active photocatalyst nanomaterial.

Distinct role of hexagonal tungsten in tungsten/ceria heterojunction in efficient utilization of visible flux

Mixed phase metal oxide photocatalysts at optimised phase ratio are known to perform better than their monophasic counterpart in visible spectrum. In tungsten oxide (WO3) too high visible activity is seen in multi-phasic systemhaving dominant hexagonal phase and is attributable to its superior photon harvesting characteristicsthan other phases. In a hetero-composite with ceria due to suitable band edge position further enhancement in the photoactivity is seen mainly with its monoclinic(m-WO3) phase. In this work, h-WO3/Ce3+/Ce4+based hetero-composites have been realized with different molar ratio of W/Ce.While h-WO3 dominates all the systems,m-WO3appears in the system at low concentration of Ce and disappears at higher concentrations. The resultant sharp increase (13.66X) in the visible photocatalytic performance of mixed phase-WO3/ceria composite compared to pristine h-WO3 shows a further jump (44X) in the monophasic-WO3/ceria composite with the highest concentration of ceria synthesized. The characterization by X-ray diffraction (XRD), UV-VIS spectroscopy (UV-VIS DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, transmission electronmicroscopy(TEM), and scanning electron microscopy(SEM) with energy dispersive x-ray analysis (EDX) reveal the complex role distinct phase junctions of homo-/hetero-composites. The mixed-phase h-WO3/m-WO3homojunction, h-WO3/Ce3+ composite heterojunction and h-WO3/Ce3+/Ce2+ with both hetero-composite (h-WO3/Ce3+ and h-WO3/Ce2+) and homo-composite(Ce3+/Ce4+) heterojunction in the samples has been identified, and their roles have been analyzed to correlate with their respective visible light photoactivity.

INVESTIGATION OF Pd@g-C3N4/TiO2 NANOPARTICLES AS PHOTOCATALYST IN THE DEGRADATION OF METHYLENE BLUE UNDER VISIBLE LIGHT IRRADIATION

In the present study, the efficiency of Pd@g-C3N4/TiO2 NPs as photocatalyst on degradation of organic pollutant methylene blue (MB) dye under visible light has been investigated. A traditional one-step impregnation-reduction method was used for the preparation of photocatalysts. Pd@g-C3N4/TiO2 NPs were characterized by several techniques such as FT-IR, DR/UV-Vis, SEM-EDX, TEM, P-XRD, and XPS analyses. The photocatalytic performance of Pd@g-C3N4/TiO2 NPs was evaluated for the degradation of MB dye under visible light irradiation. Among different loadings of Pd(0.3, 0.5, and 0.7 %), the 0.5% loading Pd@ g-C3N4/TiO2 NPs showed the highest catalytic activity. The results revealed an enhancement in the visible light photocatalytic activity of g-C3N4/TiO2 when it was coupled with Pd in the composite. Compared with pure g-C3N4/TiO2, the Pd@ g-C3N4/TiO2 hybrid photocatalyst exhibited enhanced visible light photoactivity, which was approximately three times higher than that of pure g-C3N4/TiO2.

Rationally designed Sb2S3/PDI composites with enhanced visible light photoactivity

Constructing organic-inorganic semiconductor heterojunctions is an efficient way to inhibit the recombination of photogenerated charge carriers and enhance photocatalytic performance of semiconductor. Herein, a novel heterojunction antimony sulfide-perylene diimides (Sb2S3-PDI) heterojunction has been fabricated through a facile hydrothermal method. Compared with bare Sb2S3 and PDI, the Sb2S3-PDI hybrid has showed significantly superior activity in photocatalytic reduction of Cr (VI). The superior photocatalytic performance of Sb2S3-PDI hybrid is due to the formation of type-I heterojunction, which leads to a more efficient separation and migration of photogenerated electron-hole pairs. This work is expected to promote continued interest in the construction of organic-inorganic semiconductor composites with enhanced photocatalytic performance.

Interaction of levofloxacin with reverse micelle sol-gel synthesized TiO2 nanoparticles: Revealing ligand-to-metal charge transfer (LMCT) mechanism enhances photodegradation of antibiotics under visible light

Synthesis of TiO2 through reverse micelle sol–gel (RMS) route showed 18 nm mean diameter with homogeneous particle size distribution (PDI = 0.11). TiO2 nanomaterial with a bandgap of 3.15 eV exhibited degradation efficiency of 83% towards levofloxacin (LFX) aqueous pollutant of 50 mg/L under 6H of the visible LED light. Visible light photoactivity ascribed to ligand to metal charge transfer (LMCT) process between the targeted antibiotic pollutant and titania photocatalyst. At neutral pH, photocatalytic degradation performance of TiO2 was observed higher due to adsorption of LFX through N of piperazinyl ring causing LMCT. The basic pH encouraged adsorption of LFX through the carboxylate group, which showed comparatively lesser activity. In acidic pH conditions, the lowest photoactivity resulted from the synergetic effect of lower adsorption and participation of the ketone-carboxyl adsorption site of LFX with TiO2.

Composition-dependent activity of ZnxCd1-xSe solid solution coupled with Ni2P nanosheets for visible-light-driven photocatalytic H2 generation

Metal selenide semiconductors have been rarely used for photocatalytic water splitting because of their poor stability and severe photocorrosion properties. Hence, designing stable metal selenides with suitable bandgap energies has considerable practical significance in photocatalytic H2 evolution. In this work, a novel series of ZnxCd1-xSe (x = 0 ∼ 1) with tunable band structure were fabricated through a simple solvothermal method. Impressively, the ZnSe exhibited a maximum H2 production rate of 1056 µmol g−1h−1, which was higher than that of CdSe and ZnxCd1-xSe solid solutions. Such visible-light photoactivity for water reduction to H2 was attained even after 6 cycling photocatalytic experiments. Moreover, the two-dimensional (2D) Ni2P nanosheets act as a high-efficiency cocatalyst integrated with ZnxCd1-xSe semiconductor to boost photocatalytic H2 generation performance. The optimal 8% Ni2P/ZnSe composites displayed excellent cycling stability and superior photocatalytic H2 evolution performance (4336 µmol g−1h−1), which was about 4.1 times that of pure ZnSe under visible light irradiation. Photoelectrochemical (PEC), photoluminescence (PL), and time-resolved photoluminescence (TRPL) measurements reveal that the improved photoactivity Ni2P/ZnSe photocatalysts were ascribed to the effective separation and migration of photoinduced carriers. The present work paves a pathway to explore the fabrication of ZnxCd1-xSe solid solutions and the hybridization of 2D transition metal phosphides nanosheets toward photocatalytic applications.

Preparation of magnetically retrievable flower-like AgBr/BiOBr/NiFe2O4 direct Z-scheme heterojunction photocatalyst with enhanced visible-light photoactivity

The rapid recombination of electrons and holes is the main reason affecting the performance of photocatalyst, and the difficulty in recovery of photocatalyst also impedes its practical application. Herein, the magnetically recoverable flower-like AgBr/BiOBr/NiFe2O4 (AB/BOB/NFO) ternary heterojunction photocatalyst was successfully constructed. The phase composition, morphology, the absorption of visible light of the samples, and the surface chemical environment of samples were tested by XRD, SEM, UV–vis, and XPS, respectively. Compared with pure BiOBr and BiOBr/NFO, AB/BOB/NFO showed improved photocatalytic degradation effect for RhB. 25% AB/BOB/NFO showed the best degradation performance of 100% in 90 min, which was about 3.6 times that of pure BOB. The enhanced photoactivity of AB/BOB/NFO heterojunction photocatalyst can be ascribed to the wider absorption range of visible light and the inhibited recombination of photogenerated electros and holes. Additionally, the flower-like morphology assembled by nanosheets provides more active sites and improve light absorption through reflecting multiple times and plays roles in improving the photocatalytic performance. It was also found that the AB/BOB/NFO heterojunction photocatalyst has excellent magnetic recovery ability under the action of external magnetic field. The photostability of AB/BOB/NFO heterojunction photocatalyst was also investigated, and a direct Z - type electron hole transfer mechanism was proposed according to the energy band structure. These advances provide a new way to improve the photoactivity of magnetic recyclable photocatalysts, and the as-synthesized flower-like AB/BOB/NFO has broad promising application in water environment remediation.

Hydrogenated Amorphous TiO2-x and Its High Visible Light Photoactivity.

Hydrogenated crystalline TiO2 with oxygen vacancy (OV) defect has been broadly investigated in recent years. Different from crystalline TiO2, hydrogenated amorphous TiO2−x for advanced photocatalytic applications is scarcely reported. In this work, we prepared hydrogenated amorphous TiO2−x (HA-TiO2−x) using a unique liquid plasma hydrogenation strategy, and demonstrated its highly visible-light photoactivity. Density functional theory combined with comprehensive analyses was to gain fundamental understanding of the correlation among the OV concentration, electronic band structure, photon capturing, reactive oxygen species (ROS) generation, and photocatalytic activity. One important finding was that the narrower the bandgap HA-TiO2−x possessed, the higher photocatalytic efficiency it exhibited. Given the narrow bandgap and extraordinary visible-light absorption, HA-TiO2−x showed excellent visible-light photodegradation in rhodamine B (98.7%), methylene blue (99.85%), and theophylline (99.87) within two hours, as well as long-term stability. The total organic carbon (TOC) removal rates of rhodamine B, methylene blue, and theophylline were measured to 55%, 61.8%, and 50.7%, respectively, which indicated that HA-TiO2−x exhibited high wastewater purification performance. This study provided a direct and effective hydrogenation method to produce reduced amorphous TiO2−x which has great potential in practical environmental remediation.

Enhancing the visible-light photoactivity of silica-supported TiO2 for the photocatalytic treatment of pharmaceuticals in water.

Catalyst samples based on SiO2-supported TiO2 were prepared with the incorporation of Ag (metal), S (nonmetal), and ZnO@S (semiconductor and nonmetal). The materials were evaluated regarding their morphological, optical, and crystalline properties as well as their photoactivity under visible and ultraviolet light toward the degradation rate of a model emerging pollutant, acetaminophen (ACT). All modified materials exhibited improved performance over the undoped catalyst. The Ag-doped catalyst achieved the largest degradation under visible radiation (about 30% in 120 min), whereas under ultraviolet irradiation, the ZnO@S-doped sample exhibited the best performance (about 62% in 120 min). A Doehlert design was carried out to evaluate the influence of pH and temperature on the photoactivity of Ag-TiO2/SiO2. In addition, the role of each reactive species in the photodegradation reaction was investigated by radical scavenger experiments, and the superoxide radical anion O2•- was shown to be the predominant reactive species. The stability of the Ag-TiO2/SiO2 material under ultraviolet and visible light was confirmed after five successive operation cycles, showing a reasonable (about 50%) loss of activity under visible irradiation and a slight improvement (about 13%) under UV light, as a result of the photo-reduction of Ag+. Lastly, the effect of the initial pollutant concentration showed that ACT degradation using Ag-TiO2/SiO2 follows the Langmuir-Hinshelwood kinetics, with intrinsic reaction rate k = 2.71 × 10-4 mmol L-1 min-1under visible-light radiation.

Exfoliation method matters: The microstructure-dependent photoactivity of g-C3N4 nanosheets for water purification

Exfoliation of carbon nitride (g-C3N4) into an ultrathin nanostructure significantly improves its photoactivity. However, the effects of the exfoliation method on the microstructure and photocatalytic performance of g-C3N4 nanosheets remain largely unknown. Herein, several typical strategies, such as thermal, chemical, ultrasonic and one-step exfoliation, were applied to exfoliate g-C3N4 nanosheets for photocatalytic applications. A procedure capable of controlling the morphology, microstructure, light-absorption property, and visible light photoactivity of g-C3N4 nanosheets was attempted. We found that nanosheets prepared from one-step exfoliation present superior photocatalytic efficiency under visible light than those fabricated by thermal exfoliation and ultrasonic exfoliation. The kinetic constants for bisphenol A (BPA) photodegradation over these samples were determined to be 6.5, 4.5 and 2.3 times higher than bulk g-C3N4, respectively. For chemical exfoliation, excessive oxidation by H2SO4 can lead to the structural defects and deactivation of urea-derived g-C3N4 nanosheets. Carbon nitride nanosheets synthesized by one-step exfoliation exhibited high specific surface area, optimal band gap energy structure, and high charge separation efficiency, thereby increasing visible-light photoactivity. Enabling cost-effective production of ultrathin and robust g-C3N4 nanosheets, one-step exfoliation offers a potential strategy to exploit high-performance g-C3N4 for water purification applications.