Boosting the polysulfide confinement in B/N–codoped hierarchically porous carbon nanosheets via Lewis acid–base interaction for stable Li–S batteries

Carbon materials have shown remarkable usefulness in facilitating the performance of insulating sulfur cathode for lithium–sulfur batteries owing to their excellent conductivity and porous structure. However,the anxiety is the poor affinity toward polar polysulfides due to the intrinsic nonpolar surface of carbon.Herein, we report a direct pyrolysis of the mixture urea and boric acid to synthesize B/N–codoped hierarchically porous carbon nanosheets(B–N–CSs) as efficient sulfur host for lithium–sulfur battery. The graphene–like B–N–CSs provides high specific surface area and porous structure with abundant micropores(1.1 nm) and low–range mesopores(2.3 nm), thereby constraining the sulfur active materials within the pores. More importantly, the codoped B/N elements can further enhance the polysulfide confinement through strong Li–N and B–S interaction based on the Lewis acid–base theory. These structural superiorities significantly suppress the shuttle effect by both physical confinement and chemical interaction, and promote the redox kinetics of polysulfide conversion. When evaluated as the cathode host, the S/B–N–CSs composite displays the excellent performance with a high reversible capacity up to 772 m A h g–1 at 0.5 C and a low fading rate of ^0.09% per cycle averaged upon 500 cycles. In particular, remarkable stability with a high capacity retention of 87.1% can be realized when augmenting the sulfur loading in the cathode up to 4.6 mg cm^(-2).

Visible light-driven oxidant-free dehydrogenation of alcohols in water using porous ultrathin g-C_(3)N_(4)nanosheets

Graphitic carbon nitride(g-C_(3)N_(4)) is a fascinating photocatalyst for solar energy utilization in photo-catalysis.Nevertheless,it often suffers from moderate photo-catalytic activity due to its low specific surface area and fast recombination rate of photogenerated electrons upon photo-excitation.Herein,we overcome the bottlenecks by constructing a porous g-C_(3)N_(4) nanosheet(PCNS)through a simple thermal oxidation etching method.Benefited from its porous layer structure,the obtained PCNS exhibits large specific surface area,efficient separation of photogenerated charge carriers,as well as high exposure of active sites.As a result,it is robust and universal in visible light-driven dehydrogenation of alcohols in water under oxidant-free condition.Almost quantitative yields(>99%)of various valuable carbonyl compounds were obtained over PCNS,while bulk g-C_(3)N_(4) was far less efficient.Moreover,the photo-catalyst was highly stable and could be facilely recovered from the aqueous system for efficient reuse.The easy preparation and excellent performance made PCNS a promising and competitive photocatalyst for the solar applications.

Highly sensitive electrochemical determination of rutin based on the synergistic effect of 3D porous carbon and cobalt tungstate nanosheets

Rutin,a flavonoid found in fruits and vegetables,is a potential anticancer compound with strong anticancer activity.Therefore,electrochemical sensor was developed for the detection of rutin.In this study,CoWO_(4) nanosheets were synthesized via a hydrothermal method,and porous carbon(PC)was prepared via high-temperature pyrolysis.Successful preparation of the materials was confirmed,and characterization was performed by transmission electron microscopy,scanning electron microscopy,and X-ray photoelectron spectroscopy.A mixture of PC and CoWO_(4) nanosheets was used as an electrode modifier to fabricate the electrochemical sensor for the electrochemical determination of rutin.The 3D CoWO_(4) nanosheets exhibited high electrocatalytic activity and good stability.PC has a high surface-to-volume ratio and superior conductivity.Moreover,the hydrophobicity of PC allows large amounts of rutin to be adsorbed,thereby increasing the concentration of rutin at the electrode surface.Owing to the synergistic effect of the 3D CoWO_(4) nanosheets and PC,the developed electrochemical sensor was employed to quantitively determine rutin with high stability and sensitivity.The sensor showed a good linear range(5-5000 ng/mL)with a detection limit of 0.45 ng/mL.The developed sensor was successfully applied to the determination of rutin in crushed tablets and human serum samples.

Strongly Coupled Ag/Sn-SnO_(2)Nanosheets Toward CO_(2)Electroreduction to Pure HCOOH Solutions at Ampere‑Level Current

Electrocatalytic reduction of CO_(2) converts intermittent renewable electricity into value-added liquid products with an enticing prospect,but its practical application is hampered due to the lack of high-performance electrocatalysts.Herein,we elaborately design and develop strongly coupled nanosheets composed of Ag nanoparticles and Sn-SnO_(2) grains,designated as Ag/Sn-SnO_(2) nanosheets(NSs),which possess optimized electronic structure,high electrical conductivity,and more accessible sites.As a result,such a catalyst exhibits unprecedented catalytic performance toward CO_(2)-to-formate conversion with near-unity faradaic efficiency(≥90%),ultrahigh partial current density(2,000 mA cm^(−2)),and superior long-term stability(200 mA cm^(−2),200 h),surpassing the reported catalysts of CO_(2) electroreduction to formate.Additionally,in situ attenuated total reflection-infrared spectra combined with theoretical calculations revealed that electron-enriched Sn sites on Ag/Sn-SnO_(2)NSs not only promote the formation of*OCHO and alleviate the energy barriers of*OCHO to*HCOOH,but also impede the desorption of H*.Notably,the Ag/Sn-SnO_(2)NSs as the cathode in a membrane electrode assembly with porous solid electrolyte layer reactor can continuously produce~0.12 M pure HCOOH solution at 100 mA cm^(−2)over 200 h.This work may inspire further development of advanced electrocatalysts and innovative device systems for promoting practical application of producing liquid fuels from CO_(2).

Freestanding Pt nanosheets with high porosity and improved electrocatalytic performance toward the oxygen reduction reaction

Because of the intriguing electronic properties, high specific surface areas and confinement effect, two-dimensional(2D) noble metal nanosheets usually exhibit fascinating physicochemical properties and thus hold great promises in fuel cell devices and beyond. Herein, 2D porous Pt nanosheets composed by interweaved ultrathin nanowires are successfully fabricated via a facile NaCl-templated process. Controlled experiments demonstrate that the adoption of NaCl and appropriate ratio of NaCl and Pt precursor are indispensable for the formation of porous Pt nanosheets. Impressively, the cost-effective NaCl template can be recyclable through a simple recrystallization procedure, which may greatly reduce the synthetic cost. By virtue of their structural merits, including high porosity, 2D anisotropy and abundant defects, the resultant porous Pt nanosheets exhibit superior activity and enhanced stability towards the oxygen reduction reaction(ORR) compared to the commercial Pt black in alkaline medium. The present study not only offers a high-performance electrocatalyst for fuel cell devices, but also provides a new perspective toward the rational synthesis of 2D noble metal nanosheets with high porosity and diverse functionalities.

Advanced membrane separation based on two-dimensional porous nanosheets

Two-dimensional porous nanosheets such as metal-organic frameworks,covalent organic frameworks,fluorides of light lanthanide,and perforated graphene oxide are a class of nanomaterials with sheet-like morphologies and defined pore structures.Due to their porous structure and large lateral sizes,these materials exhibit excellent molecular transport properties in separation processes.This review focuses on the pore formation strategies for two-dimensional porous nanosheets and applications of these nanosheets and their constructed membranes in gas separation processes and separation processes applicable to water treatment and the humidity control of gas permeation.A brief discussion of challenges and future developments of separation applications with two-dimensional porous nanosheets and their constructed membranes is included in this review.

Stacking MoS_(2) flower-like microspheres on pomelo peels-derived porous carbon nanosheets for high-efficient X-band electromagnetic wave absorption

The key to solve increasingly severe electromagnetic(EM)pollution is to explore sustainable,easily prepared,and cost-effective EM wave absorption materials with exceptional absorption capability.Herein,instead of anchoring on carbon materials in single layer,MoS_(2) flower-like microspheres were stacked on the surface of pomelo peels-derived porous carbon nanosheets(C)to fabricate MoS_(2)@C nanocomposites by a facile solvothermal process.EM wave absorption performances of MoS_(2)@C nanocomposites in X-band were systematically investigated,indicating the minimum reflection loss(RLmin)of-62.3 dB(thickness of 2.88 mm)and effective absorption bandwidth(EAB)almost covering the whole X-band(thickness of 2.63 mm)with the filler loading of only 20 wt.%.Superior EM wave absorption performances of MoS_(2)@C nanocomposites could be attributed to the excellent impedance matching characteristic and dielectric loss capacity(conduction loss and polarization loss).This study revealed that the as-prepared MoS_(2)@C nanocomposites would be a novel prospective candidate for the sustainable EM absorbents with superior EM wave absorption performances.

Modulating nanograin size and oxygen vacancy of porous ZnO nanosheets by highly concentrated Fe-doping effect for durable visible photocatalytic disinfection

Visible light-driven environmentally friendly ZnO semiconductor for durable photocatalytic disinfection and purification of drinking water is very promising.However,the high requirement in ultraviolet absorption and rapid recombination velocity of the photogenerated electron-hole severely hamper the sustainable implementation of ZnO in photocatalysis.Herein,by one"two birds with one stone"strategy,Fe-doping ZnO porous nanosheets(Fe-ZnOPN)composed of ultrafine nanoparticles can be constructed by hydrothermal synthesis of basic zinc carbonate and controlled low-temperature pyrolytic methods.By highly concentrated Fe-doping effect(>7 wt%),the tailoring ZnO nanograin size(~10 nm)and rich oxygen vacancy of catalyst were accessed by ion/vacancy diffusion and nanocrystal rearrangement,superior to the ZnO porous nanosheets(~37 nm).The obtained Fe-ZnOPN were endowed with a larger specific surface area,improved visible light harvesting ability,light response and separation of charge carriers.Such characters allowed the resulting catalyst to afford a 100%bactericidal efficiency against Pseudomonas aeruginosa and Staphylococcus aureus under visible light irradiation(>420 nm).Impressively,the Fe-ZnOPN could show practical disinfection ability in different water resources and multiple reuse ability.The mechanism study revealed that excellent photocatalytic disinfection performance of Fe-ZnOPN correlated with the in situ generated active oxidative substances,destruction of bacterial biofilm and resulting nucleic acids leakage,thereby causing irreversible physical damage.This study provided a new reference for designing environmentally friendly photocatalytic sterilization materials and disinfectants,which can be used in the practical disinfection of drinking water.

Fe nanoclusters anchored in biomass waste-derived porous carbon nanosheets for high-performance supercapacitor

Metal-nanocluster materials have gradually become a promising electrode candidate for supercapaci-tor application.The high-efficient and rational architecture of these metal-nanocluster electrode mate-rials with satisfied supercapacitive performance are full of challenges.Herein,Fe-nanocluster anchored porous carbon(FAPC)nanosheets were constructed through a facile and low-cost impregnation-activation strategy.Various characterization methods documented that FAPC nanosheets possessed a mesopore-dominated structure with large surface area and abundant Fe-N4 active sites,which are crucial for su-percapacitive energy storage.The optimal FAPC electrode exhibited a high specific capacitance of 378 F/g at a specific current of 1 A/g and an excellent rate capability(271 F/g at 10 A/g),which are comparable or even superior to that of most reported carbon candidates.Furthermore,the FAPC-based device achieved a desired specific energy of 14.8 Wh/kg at a specific power of 700 W/kg.This work opens a new avenue to design metal-nanocluster materials for high-performance biomass waste-based supercapacitors.

Integrating single Ni site and PtNi alloy on two-dimensional porous carbon nanosheet for efficient catalysis in fuel cell

The performance of catalyst depends on the intrinsic activity of active sites and the structural characteristics of the support.Here,we simultaneously integrate single nickel(Ni)sites and platinum-nickel(PtNi)alloy nanoparticles(NPs)on a two-dimensional(2D)porous carbon nanosheet,demonstrating remarkable catalytic performance in the oxygen reduction reaction(ORR).The single Ni sites can activate the oxygen molecules into key oxygen-containing intermediate that is further efficiently transferred to the adjacent PtNi alloy NPs and rapidly reduced to H_(2)O,which establishes a relay catalysis between active sites.The porous structure on the carbon nanosheet support promotes the transfer of active intermediates between these active sites,which assists the relay catalysis by improving mass diffusion.Remarkably,the obtained catalyst demonstrates a half-wave potential of up to 0.942 V,a high mass activity of 0.54 A·mgPt^(−1),and negligible decay of activity after 30,000 cycles,which are all superior to the commercial Pt/C catalysts with comparable loading of Pt.The theoretical calculation results reveal that the obtained catalyst with defect structure of carbon support presents enhanced relay catalytic effect of PtNi alloy NPs and single Ni sites,ultimately realizing improved catalytic performance.This work provides valuable inspiration for developing low platinum loading catalyst,integrating single atoms and alloy with outstanding performance in fuel cell.

Spinel MnCo2O4 nanoparticles cross-linked with two-dimensional porous carbon nanosheets as a high-efficiency oxygen reduction electrocatalyst

Catalysts for the oxygen reduction reaction （ORR） play an important role in fuel cells. Alternative non-precious metal catalysts with comparable ORR activity to Pt-based catalysts are highly desirable for the development of fuel cells. In this work, we report for the first time a spinel MnC0204/C ORR catalyst consisting of uniform MnC0204 nanoparticles cross-linked with two-dimensional （2D） porous carbon nanosheets （abbreviated as porous MnC0204/C nanosheets）, in which glucose is used as the carbon source and NaC1 as the template. The obtained porous MnCo204/C nanosheets present the combined properties of an interconnected porous architecture and a large surface area （175.3 m2-g-1）, as well as good electrical conductivity （1.15 x 102 S.cm-1）. Thus, the as-prepared MnC0204/C nanosheets efficiently facilitate electrolyte diffusion and offer an expedite transport path for reactants and electrons during the ORR. As a result, the as-prepared porous MnC0204/C nanosheet catalyst exhibits enhanced ORR activity with a higher onset potential and current density than those of its counterparts, including pure MnC0204, carbon nanosheets, and Vulcan XC-72R carbon. More importantly, the porous MnC0204/C nanosheets exhibit a com- parable electrocatalytic activity but superior stability and tolerance toward methanol crossover effects than a high-performance Pt/C catalyst in alkaline medium. The synthetic strategy outlined here can be extended to other non- precious metal catalysts for application in electrochemical energy conversion.

Surface density of synthetically tuned spinel oxides of Co^(3+) and Ni^(3+) with enhanced catalytic activity for methane oxidation

Spinel oxides containing Co and Ni are a promising substitute as a noble metal catalyst for methane combustion.Achieving a complete oxidation of methane under 400°C remains challenging,andhydrothermal 60 h NiClittle impact on activity,especially at high space velocities due to the long hydrothermal time with less absorbed oxygen species and crystal defects.Overall,these results help clarify methane activa-tion mechanisms and aid the development of more efficient low-cost catalysts.

Embedding tin disulfide nanoparticles in twodimensional porous carbon nanosheet interlayers for fast-charging lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have attracted significant attention for their high specific capacity,non-toxic and harmless advantages.However,the shuttle effect limits their development.In this work,small-sized tin disulfide(SnS_(2))nanoparticles are embedded between interlayers of twodimensional porous carbon nanosheets(PCNs),forming a multi-functional nanocomposite(PCN-SnS_(2))as a cathode carrier for Li-S batteries.The graphitized carbon nanosheets improve the overall conductivity of the electrode,and the abundant pores not only facilitate ion transfer and electrolyte permeation,but also buffer the volume change during the charge and discharge process to ensure the integrity of the electrode material.More importantly,the physical confinement of PCN,as well as the strong chemical adsorption and catalytic reaction of small SnS_(2)nanoparticles,synergistically reduce the shuttle effect of polysulfides.The interaction between a porous layered structure and physical-chemical confinement gives the PCN-SnS_(2)-S electrode high electrochemical performance.Even at a high rate of 2 C,a discharge capacity of 650 mA h g^(-1)is maintained after 150 cycles,underscoring the positive results of SnS_(2)-based materials for Li-S batteries.The galvanostatic intermittent titration technique results further confirm that the PCN-SnS_(2)-S electrode has a high Li+transmission rate,which reduces the activation barrier and improves the electrochemical reaction kinetics.This work provides strong evidence that reducing the size of SnS_(2)nanostructures is beneficial for capturing and reacting with polysulfides to alleviate their shuttle effect in Li-S batteries.

Sulfur-doped g-C3N4/rGO porous nanosheets for highly efficient photocatalytic degradation of refractory contaminants

Graphitic carbon nitride(g-C3N4,CN)has attracted increasing interests in the field of photocatalysis due to its high visible-light-response.However,its photocatalytic activity is still lower for degradation of refractory contaminants such as Cr(Ⅵ)and Rhodamine B(RhB)etc.Herein,we report a facile method to synthesize a novel sulfur(S)-doped CN/reduced graphene oxide(rGO)porous nanosheet(S-CN/rGO PNs)via a supramolecular self-assembling followed by a solvothermal treatment.The as-prepared porous SCN/rGO PNs are stable with high specific surface area^188.5 m2 g-1 and exhibit a significantly enhanced photocatalytic activity of^17-fold and 15-fold higher than that of bulk CN for the degradation of RhB and Cr(Ⅵ)under visible light irradiation,respectively.Typically,50 mL of 15 mg/mL RhB can be degraded within 20 min by 10 mg S-CN/rGO PNs.The mechanism can be explained by the synergistic effect of S doping and porous structure which can effectively reduce the band gap of CN and increase the specific surface area to promote the separation and transfer of photo-generated charge carriers.The results have provided a new way to significantly enhance the photocatalytic activity of g-C3N4 for degradation of refractory contaminants.

Improved triethylamine sensing properties of fish-scale-like porous SnO_(2) nanosheets by decorating with Ag nanoparticles

Three dimensional(3D)porous nanostructures assembled by low-dimensional nanomaterials are widely applied in gas sensor according to porous structure which can facilitate the transport of gas molecules.In this work,fish-scale-like porous SnO 2 nanomaterials assembled from ultrathin nanosheets with thick-ness of 16.8 nm were synthesized by a facile hydrothermal route.Then Ag nanoparticles were decorated on the surface of SnO_(2) nanosheets via one-step method to improve their gas-sensing performances.The sensing properties of pristine SnO_(2) and Ag/SnO_(2) nanosheets were investigated intensively.After deco-rating with Ag nanoparticles,the characteristics of SnO_(2) based sensor for triethylamine detection were significantly improved.Especially,the Ag/SnO_(2) based sensor with Ag content of 2 at%exhibited the highest triethylamine sensing sensitivity at optimum work temperature of 170?C.The improved sensing properties of Ag/SnO_(2) sensors were attributed to the sensitizing actions of Ag nanoparticles as well as the unique hierarchical porous architecture.

Ruthenium-modified porous NiCo2O4 nanosheets boost overall water splitting in alkaline solution

Exploring efficient oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)electrocatalysts is crucial for developing water splitting devices.The composition and structure of catalysts are of great importance for catalytic performance.In this work,a heterogeneous Ru modified strategy is engineered to improve the catalytic performance of porous NiCo_(2)O_(4)nanosheets(NSs).Profiting from favorable elements composition and optimized structure property of decreased charge transfer barrier,more accessible active sites and increased oxygen vacancy concentration,the Ru-NiCo_(2)O_(4)NSs exhibits excellent OER activity with a low overpotential of 230 mV to reach the current density of 10 mA/cm^(2)and decent durability.Furthermore,Ru-NiCo_(2)O_(4)NSs show superior HER activity than the pristine NiCo_(2)O_(4)NSs,as well.When assembling Ru-NiCo_(2)O_(4)NSs couple as an alkaline water electrolyzer,a cell voltage of 1.60 V can deliver the current density of 10 mA/cm^(2).This work provides feasible guidance for improving the catalytic performance of spinel-based oxides.

Few-layered MoS_(2)anchored on 2D porous C_(3)N_(4)nanosheets for Ptfree photocatalytic hydrogen evolution

The Pt-free photocatalytic hydrogen evolution(PHE)has been the focus in the photocatalytic field.The catalytic system with the large accessible surface and good mass-transfer ability,as well as the intimate combination of co-catalyst with semiconductor is promising for the promotion of the application.Here,we have reported the design of the two-dimensional(2D)porous C_(3)N_(4)nanosheets(PCN NS)intimately combined with few-layered MoS_(2)for the high-effective Pt-free PHE.The PCN NS were synthesized based on peeling the melamine–cyanuric acid precursor(MC precursor)by the triphenylphosphine(TP)molecular followed by the calcination,mainly due to the matched size of the(100)plane distance of the precursor(0.8 nm)and the height of TP molecular.The porous structure is favorable for the mass-transfer and the 2D structure having large accessible surface,both of which are positive to promote the photocatalytic ability.The few-layered MoS_(2)are grown on PCN to give 2D MoS_(2)/PCN composites based on anchoring phosphomolybdic acid(PMo_(12))cluster on polyetherimide(PEI)-modified PCN followed by the vulcanization.The few-layered MoS_(2)have abundant edge active sites,and its intimate combination with porous PCN NS is favorable for the faster transfer and separation of the electrons.The characterization together with the advantage of 2D porous structure can largely promote the photocatalytic ability.The MoS_(2)/PCN showed good PHE activity with the high hydrogen production activity of 4,270.8μmol·h^(−1)·g^(−1)under the simulated sunlight condition(AM1.5),which was 7.9 times of the corresponding MoS_(2)/bulk C_(3)N_(4)and 12.7 times of the 1 wt.%Pt/bulk C_(3)N_(4).The study is potentially meaningful for the synthesis of PCN-based catalytic systems.

Large-scale multirole Zn(Ⅱ) programmed synthesis of ultrathin hierarchically porous carbon nanosheets

ZIF-derived carbon structures are considered as desired electrode materials for supercapacitors due to their high surface area,high conductivity, and porous structure. However, the most reported ratio of 2-methylimidazole and Zn(II) is 4:1 to 20:1, which limits commercial applications due to the increasing cost. In this paper, a multirole Zn(II)-assisted method is presented from Zn(II) solution, Zn O, Zn O/ZIF-8 core-shell nanostructure, to 3 D hierarchical micro-meso-macroporous carbon structures with a1:1 ratio of 2-methylimidazole and Zn(II). The hierarchically porous carbon has a high surface area of 1800 m2 g^(-1) due to the synergistic effect of multirole Zn(II). The unique carbon-based half-cell delivers the specific capacitances of 377 and 221 F g^(-1) at the current densities of 1.0 and 50 A g^(-1), respectively. As a 2.5 V symmetrical supercapacitor, the device reveals a high doublelayer capacitance of 24.4 F g^(-1), a power density of 62.5 k W kg^(-1), and more than 85.8% capacitance can be retained over 10000 cycles at 10 A g^(-1). More importantly, the low-cost hierarchically porous carbon could be easily produced on a large scale and almost all chemicals can be reused in the sustainable method.

TiO_(2)bunchy hierarchical structure with effective enhancement in sodium storage behaviors

Bronze phase TiO_(2)[TiO_(2)(B)]has great research potential for sodium storage since it has a higher theoretical capacity and ion mobility compared with other phases of TiO_(2).In this case,preparing porous TiO_(2)(B)nanosheets,which can provide abundant sodium insertion channels,is the most effective way to improve transport kinetics.Here,we use the strong one-dimensional TiO_(2)nanowires as the matrix for stringing these nanosheets together through a simple solvothermal method to build a bunchy hierarchical structure[TiO_(2)(B)-BH],which has fast pseudocapacitance behavior,high structural stability,and effective ion/electron transport.With the superiorities of this structure design,TiO_(2)(B)-BH has a higher capacity(131 vs.70 mAh g^(−1)[TiO_(2)-NWs]at 0.5 C).And it is worth mentioning that the reversible capacity of up to 500 cycles can still be maintained at 85 mAh g^(−1)at a high rate of 10 C.Meanwhile,we also further analyzed the sodium storage mechanism through the ex-situ X-ray powder diffraction test,which proved the high structural stability of TiO_(2)(B)-BH in the process of sodiumization/de-sodiumization.This strategy of uniformly integrating nanosheets into a matrix can also be extended to preparing electrode material structures of other energy devices.

Boosted charge transfer and photocatalytic CO_(2) reduction over sulfurdoped C_(3)N_(4) porous nanosheets with embedded SnS_(2)-SnO_(2) nanojunctions

Two-dimensional porous nanosheet heterostructure materials,which combine the advantages of both architecture and components,are expected to feature a significant photocatalytic performance toward CO_(2) conversion into useful fuels.Herein,we provide a facile strategy for fabricating sulfur-doped C_(3)N_(4) porous nanosheets with embedded SnO_(2)-SnS_(2) nanojunctions(S-C_(3)N_(4)/SnO_(2)-SnS_(2))via liquid impregnation-pyrolysis and subsequent sulfidation treatment using a layered supramolecular structure as the precursor of C_(3)N_(4).A hexagonal layered supramolecular structure was first prepared as the precursor of C_(3)N_(4).Then Sn^(4+) ions were intercalated into the supramolecular interlayers through the liquid impregnation method.The subsequent annealing treatment in air simultaneously realized the fabrication and efficient exfoliation of layered C_(3)N_(4) porous nanosheets.Moreover,SnO_(2) nanoparticles were formed and embedded in situ in the porous C_(3)N_(4) nanosheets.In the following sulfidation process under a nitrogen atmosphere,sulfur powder can react with SnO_(2) nanoparticles to form SnO_(2)-SnS_(2) nanojunctions.As expected,the exfoliation of sulfur-doped C_(3)N_(4) porous nanosheets and ternary heterostructure construction could be simultaneously achieved in this work.Sulfur-doped C_(3)N_(4) porous nanosheets with embedded SnO_(2)-SnS_(2) nanojunctions featured abundant active sites,enhanced visible light absorption,and efficient interfacial charge transfer.As expected,the optimized S-C_(3)N_(4)/SnO_(2)-SnS_(2) achieved a much higher gas-phase photocatalytic CO_(2) reduction performance with high yields of CO(21.68μmol g^(−1)h^(−1))and CH_(4)(22.09μmol g^(−1)h^(−1))compared with the control C_(3)N_(4),C_(3)N_(4)/SnO_(2),and S-C_(3)N_(4)/SnS_(2) photocatalysts.The selectivity of CH_(4) reached 80.30%.Such a promising synthetic strategy can be expected to inspire the design of other robust C_(3)N_(4)-based porous nanosheet heterostructures for a broad range of applications.