The incorporation of cocatalyst cobalt sulfide into graphitic carbon nitride:Boosted photocatalytic hydrogen evolution performance and mechanism explorationOA

2D-layered graphitic carbon nitride(g-C₃N₄ ) is regarded as a great prospect as a photocatalyst for H₂ generation.However, g-C₃N₄’s photocatalytic hydrogen evolution(HER) activity is significantly restricted by the recombination of photocarriers. We find that cobalt sulfide(CoS₂) as a cocatalyst can promote g-C₃N₄ nanosheets(NSs) to realize very efficient photocatalytic H₂ generation. The prepared ...     

Boosting photocatalytic hydrogen evolution of g-C3N4 catalyst via lowering the Fermi level of co-catalyst

The photocatalytic performances are highly dependent on the charge separation and surface reaction kinetics of photocatalysts.Aiming at figuring out the effects of co-catalyst with the lower Fermi level on photocatalytic activity,we tuned the Fermi level of Pt nanoparticles on g-C₃N₄(GCN)by introducing Co atom.Experimental results show that lowering the Fermi level of co-catalyst does not alter light absorption of GCN due to the invariable structure.Besides,Pt₃Co with a lower Fermi level contributes less positive influence on charge separation in GCN due to an opposite effect from the stronger electron-trap ability of Pt₃Co and increased band bending in GCN-Pt₃Co.The density functional theory(DFT)calculations indicate that GCN-Pt₃Co has faster surface reaction kinetics than GCN-Pt,owing to easier dissociation of H₂O molecules and faster desorption of H^*on Pt₃Co.Consequently,GCN-Pt₃Co exhibits an excellent H₂ evolution rate with 2.91 mmol g^-1·h^-1,which 2.67 times that of GCN-Pt.     

Facile synthesis of C3N4-supported metal catalysts for efficient CO2 photoreduction

Facile synthesis of photocatalysts with highly dispersed metal centers is a high-priority target yet still a significant challenge.In this work,a series of Co-C₃N₄ photocatalysts with different Co contents atomically dispersed on g-CaN4 have been prepared via one-step thermal treatment of cobalt-based metal-organic frameworks(MOFs)and urea in the air.Thanks to the highly dispersed and rich exposed Co sites,as well as good charge separation efficiency and abundant mesopores,the optimal 25-Co-C₃N₄,in the absence of noble metal catalysts/sensitizers,exhibits excellent performance for photocatalytic C0₂ reduction to CO under visible.light irradiation,with a high CO evolution rate of 394.4μmol·g^-1·h^-1,over 80 times higher than that of pure g-C₃N₄(4.9μmol·g^-1·h^-1).In:addition,by this facile synthesis strategy,the atomically dispersed Fe and Mn anchoring on g-C₃N₄(Fe-C₃N₄ and Mn-C₃N₄)have been also obtained,indicating the reliability and universality of this strategy in synthesizing photocatalysts with highly dispersed metal centers.This work paves a new way to develop cost-effective photocatalysts for photocatalytic C0₂ reduction.     

Developing high photocatalytic antibacterial Zn electrodeposited coatings through Schottky junction with Fe3+-doped alkalized g-C3N4 photocatalystsOA

Pure Zn coatings easily lose their protective performance after biofouling because they have no antibacterial effect under visible light. In this study, we fabricate a new antibacterial Zn composite coating using electrodeposition to couple Fe³⁺-doped alkalized g-C₃N₄(AKCN-Fe) into an existing Zn coating and show that the AKCN-Fe enhances antibacterial property of the Zn coating under visible light. We attribute this enhancement to the high photocatalytic perform...     

Earth-Abundant CaCO3-Based Photocatalyst for Enhanced ROS Production,Toxic By-Product Suppression,and Efficient NO Removal

Photoinduced reactive oxygen species(ROS)-based pollutant removal is one of the ideal solutions to achieve the conversion of solar energy into chemical energy and thus to address environmental pollution. Here, earthabundant CaCO₃-decorated g-C₃N₄ (g-C₃N₄ labeled as CN, CaCO₃-decorated g-C₃N₄ sample labeled as CN-CCO) has been constructed by a facile thermal polymerization method for safe and efficient photoca...     

MXene Ti3C2 decorated g-C3N4/ZnO photocatalysts with improved photocatalytic performance for CO2 reductionOA

Photocatalytic reduction of CO₂ is considered as a kind of promising technologies for solving the greenhouse effect. Herein, a novel hybrid structure of g-C₃N₄/ZnO/Ti₃C₂ photocatalysts was designed and fabricated to investigate their abilities for CO₂ reduction. As demonstration, heterojunction of g-C₃N₄/ZnO can improve photogenerated carriers’ separation, the addition of Ti₃C₂ fragments...     

Surface disorder engineering in ZnCdS for cocatalyst free visible light driven hydrogen production

Metal chalcogenide solid solution,especially ZnCdS,has been intensively investigated in photocatalytic H₂ generation due to their cost-effective synthetic procedure and adjustable band structures.In this work,we report on the defect engineering of ZnCdS with surface disorder layer by simple room temperature Li-ethylenediamine(Li-EDA)treatment.Experimental results confirm the formation of unusual Zn and S dual vacancies,where rich S vacancies(Vs)served as electron trapping sites,meanwhile Zn vacancies(Vzn)served as hole trapping sites.The refined structure significantly facilitates the photo charge carrier transfer and improves photocatalytic properties of ZnCdS.The disordered ZnCdS shows a highest photocatalytic H₂ production rate of 33.6 mmol·g^-1·h^-1 under visible light with superior photocatalytic stabilities,which is 7.3 times higher than pristine ZnCdS and 7 times of Pt(1 wt.%)loaded ZnCdS.     

Hetero-phase MoC-Mo2C nanoparticles for enhanced photocatalytic H2-production activity of TiO2

Hexagonal molybdenum carbide(Mo₂C)as an effective non-noble cocatalyst is intensively researched in the photocatalytic H₂-evolution field owing to its Pt-like H⁺-adsorption ability and good conductivity.However,hexagonal Mo₂C-modified photocatalysts possess a limited H₂-evolution rate because of the weak H-desorption ability.Tofurther improve the activity,cubic MoC was introduced into Mo₂C toform the carbon-modified MoC-Mo₂C nanoparticles(MoC-Mo₂C@C)by a calcination method.The resultant MoC-Mo₂C@C(ca.5 nm)was eventually coupled with Ti0₂to acquire high-efficiency Ti0₂/MoC-Mo₂C@C by electrostatic self-assembly.The highest H₂-generation rate of Ti0₂/MoC-Mo₂C@C reached of 918μmol·h^-1·g^-1which was 91.8,2.7,and 1.5 times than that of the Ti0₂,TiO₂/MoC@C,and Ti0₂/Mo₂C@C,respectively.The enhanced rate of Ti0₂attributes to the carbon layer as cocatalyst to transmit electrons and the hetero-phase MoC-Mo₂C as H₂-generation active sites to boost H₂-evolution reaction.This research offers a novel insight to design photocatalytic materials for energy applications.     

New design concept for stable α-silicon nitride based on the initial oxidation evolution at the atomic and molecular levels

As the dominated composition of Si₃N₄ceramics, α-silicon nitride(α-Si₃N₄) can satisfy the strength and fracture toughness demand in the applications. However, α-Si₃N₄is oxygen-sensitive at high temperatures, which limits its high-temperature performance. To improve the oxidation resistance of α-Si₃N₄ceramics, it is necessary to shed light on the oxidation mechanism. Herein, the initial oxidation of α-Si_3...     

Oriented electron tunneling transport in hierarchical Ag/SiO2/TiO2 nanobowl arrays for plasmonic solar water splitting

Hierarchical Ag/SiO₂/TiO₂ nanobowl(NB)arrays were fabricated for use as plasmonic photoanodes for solar-hydrogen conversion.The nanobowls had large pore size and were composed of an upper TiO₂ nanoring and a lower TiO₂ nanohole.A thin SiO₂ inter-layer was introduced as an electron transmission channel to change the mechanism of hot electron transport.Simulations were performed to characterize the variation of electron concentration in Ag/SiO₂/TiO₂ NB arrays,taking into account both the optical transition of photogenerated electrons,and electron tunneling.The multiphysics coupling function of COMSOL software provided the light source for optical transition of photogenerated electrons,and a Wentzel-Kramers-Brillouin model was employed to represent the tunneling.The results demonstrate that the TiO₂ nanoring was a transporter,which transmitted electrons downward to the nanohole.The SiO₂ layer replaces the Schottky barrier to become a bridge for tunneling of hot electrons in high-and low-energy states into TiO₂.Moreover,the coverage of the SiO₂ layer helped increase the light absorption of TiO₂,it also reduced the near electric field coupling between Ag and TiO₂.Accordingly,under AM 1.5 light irradiation,the photocurrent density and average hydrogen evolution rate of Ag/SiO₂/TiO₂ were 1.8 and 2.2 times higher,respectively,than those of pure TiO₂,implying far more efficient migration of carriers.     

Dielectric,Electromagnetic Interference Shielding and Absorption Properties of Si3N4-PyC Composite Ceramics

Pyrolytic carbon（PyC） was infiltrated into silicon nitride（Si₃N₄） ceramics by precursor infiltration and pyrolysis （PIP） of phenolic resin,and Ni nanoparticles were added into the phenolic resin to change the electric conductivity of Si₃N₄-PyC composite ceramics.Dielectric permittivity,electromagnetic interference（EMI） shielding and absorption properties of Si₃N₄—PyC composite ceramics were studied as a function of Ni content at 8.2—12.4 GHz（X-band）.When Ni nanoparticles were added into phenolic resin,the electric conductivity of the prepared composite ceramics decreased with increasing Ni content,which was attributed to the decrease of graphitization degree of PyC.The decrease in electric conductivity led to the decrease in both permittivity and EMI shielding effectiveness.Since too high permittivity is harmful to the impendence match and results in the strong reflection,the electromagnetic wave absorption property of Si₃N₄—PyC composite ceramics increases with increasing Ni content.When the content of Ni nanoparticles added into phenolic resin was 2 wt%,the composite ceramics possessed the lowest electric conductivity and displayed the most excellent absorption property with a minimum reflection loss as low as -28.9 dB.     

Construction of oxygen vacancy on Bi12O17Cl2 nanosheets by heat-treatment in H2O vapor for photocatalytic NO oxidation

Oxygen-vacancies(OVs) play significant roles in semiconductor-based photocatalysis,such as elevating light absorption property,photogenerated carries separation efficiency,molecular activation,and photocatalytic activity.However,heat-treatment of semiconductors in dangerous H₂ atmosphere is usually indispensable for OVs formation.In this work,C-doped Bi₁₂O₁₇C₁₂ nanosheets were facially heat-treated in H₂O vapor(～2.3 vol%) mixed with Ar at 30...     

碳纳米球复合g-C3N4提升光催化降解酸性橙Ⅱ性能

基于g-C₃N₄构建的异质结光催化材料在降解有毒有害污染物方面体现出优良的效果。本研究通过水热法制备了一系列不同碳纳米球(Carbon nanospheres,CS)添加量的x-CS/g-C₃N₄ (x=4wt%、5wt%和7wt%)复合光催化剂,以氙灯光源模拟可见光,探究了x-CS/g-C₃N₄对酸性橙Ⅱ的光催化降解性能。结果表明:5wt% CS/g-C₃N₄的光催化活性最高,光催化反应150 min,酸性橙Ⅱ的降解率达到95%。表征结果表明,g-C₃N₄与CS具有类似的π-π共轭结构,易发生π-π堆积相互作用而有利于电子跃迁。二者复合后能有效增强g-C₃N₄对可见光的吸收效率,降低其表面/界面处的电荷转移电阻,显著增强载流子的传输能力。x-CS/g-C₃N₄可作为一种有效的可见光催化剂应用于有机染料降解,具有应用前景。      

Efficient interfacial charge transfer of BiOCl-In2O3 step-scheme heterojunction for boosted photocatalytic degradation of ciprofloxacin

BiOCl as a representative layered bismuth-based photocatalyst with Sillén-structure has aroused wide public concern on photocatalytic degradation. However, the photocatalytic efficiency of pristine BiOCl is currently restricted by its low optical absorption and charge separation efficiency. Herein, step-scheme (S-scheme) heterojunctions of In₂O₃nanoparticle and BiOCl micron-sheet were constructed by a convenient molten salt method by using a LiNO₃-KNO₃...     

Study on mechanism of low-temperature oxidation of n-hexanal catalysed by 2D ultrathin Co3O4 nanosheets

Achieving high catalytic performance with lower possible cost and higher energetic efficiency is critical for catalytic oxidation of volatile organic compounds(VOCs).However,traditional thermocatalysts generally undergo low catalytic activity and fewer active sites.Herein,this paper synthesizes nearly all-surface-atomic,ultrathin two-dimensional(2D)Co₃O₄ nanosheets to address these problems through offering a numerous active sites and high electron mobility.The 2D Co₃O₄ nanosheets(1.70 nm)exhibit catalyzation to the total oxidation of n-hexanal at the lower temperature of r90%=202℃,and at the space velocity of 5.0×10⁴ h^-1.It is over 1.2 and 6 times higher catalytic activity than that of 2D CoO nanosheets(1.71 nm)and bulk Co₃O₄ counterpart,respectively.Transient absorption spectroscopy analysis shows that the oxygen vacancy defect traps electrons,thereby preventing the recombination with holes,increasing the lifetime of electrons,and making electron-holes reach a nondynamic equilibrium.The longer the electron lifetime is,the easier the oxygen vacancy defects capture electrons.Furthermore,the defects combine with oxygen to form active oxygen components.Compared with the lattice oxygen involved in the reaction of bulk Co₃O₄,the nanosheets change the catalytic reaction path,which effectively reduces the activation energy barrier from 34.07 to 27.15 kJ/mol.The changed surface disorder,the numerous coordinatively-unsaturated Co atoms and the high ratio of O_ads/O_lat on the surface of 2D Co₃O₄ nanosheets are responsible for the catalytic performance.     

Plasmonic TiN nanobelts assisted broad spectrum photocatalytic H2 generation

The conversion of solar energy in a wide spectrum region to clean fuel, H₂, remains a challenge in the field of photocatalysis. Herein, plasmonic Ti N nanobelts, as a novel cocatalyst, were coupled with Cd S nanoparticles to construct a 0D/1D CdS/TiN heterojunction. Utilization of the localized surface plasmon resonance(LSPR) effect generated from TiN nanobelts was effective in promoting light absorption in the near-infrared region, accelerating charge separation, and generating hot e...     

Light-responsive color switching of self-doped TiO2-x/WO3·0.33H2O hetero-nanoparticles for highly efficient rewritable paper

Smart materials that reversibly change color upon light illumination are widely explored for diverse appealing applications.However,light-responsive color switching materials are mainly limited to organic molecules.The synthesis of inorganic counterparts has remained a significant challenge because of their slow light response and poor reversibility.Here,we report a seeded growth strategy for the synthesis of TiO_2-x/WO₃·0.33H₂Ohetero-nanoparticles(HNPs)with networked wire-like structure of?10 nm in diameters that enable the highly reversible light-responsive color switching properties.For the TiO_2-x/WO₃·0.33H₂OHNPs,T P species self-doped in TiO_2-xnanoparticles(NPs)act as efficient sacrificial electron donors(SEDs)and Ti-O-W linkages formed between TiO2-x and WO30.33H2O NPs ensure the nanoscale interfacial contact,endowing the HNPs enhanced photoreductive activity and efficient interfacial charge transfer upon ultraviolet(UV)illumination to achieve highly efficient color switching.The TiO_2-x/WO₃·0.33H₂OHNPs exhibits rapid light response(<15 s)and long reversible color switching cycles(>180 times).We further demonstrate the applications of TiO_2-x/WO₃·0.33H₂O HNPs in ink-free,light-printable rewritable paper that can be written on freehand or printed on through a photomask using UV light.This work opens an avenue for designing inorganic light-responsive color switching nanomaterials and their smart applications.     

白光g-C3N4/CaMoO4∶Eu3+荧光粉的合成及发光性能研究

采用高温固相法合成CaMoO₄∶Eu³⁺红色荧光粉，采用热解法制备g-C₃N₄蓝色荧光粉，并制备复合荧光粉g-C₃N₄/CaMoO₄∶Eu³⁺。利用X射线衍射、荧光光谱分析、热猝灭分析对荧光粉进行了表征。结果表明，CaMoO₄∶Eu³⁺红色荧光和复合荧光粉g-C₃N₄/CaMoO₄∶Eu³的衍射峰与CaMoO₄粉末标准卡PDF#85-1267的衍射峰相匹配。在393nm的激发下，g-C₃N₄在462nm处发蓝绿色光，CaMoO₄∶Eu³⁺在616nm处发红色光。通过改变g-C₃N₄与CaMoO₄∶Eu^...     

Photothermy-strengthened photocatalytic activity of polydopamine-modified metal-organic frameworks for rapid therapy of bacteria-infected wounds

Herein,a metal-organic framework(MOF)was modified using polydopamine(PDA)to develop the MOFPDA as a photoresponsive bacteria-killing agent under 660 nm light irradiation.The modification using PDA led to the production of not only more heat,but also much more~1O₂.This is because the PDA could interact with the porphyrin ring of the MOF throughπ-πinteraction and the charge transfer between PDA and the MOFs decreases the ene rgy of the band of hybrid nanoparticles.In addition,greater levels of hyperthermia induced by PDA modification accelerated the charge trans fe r,which significantly strengthened the photocatalytic perfo rmance of MO F-PDA.Furthermore,after modification,the light abso rbance and water dispersibility of nanoparticles were both enhanced;both are important for the improvement of photocatalytic and photothermal properties.Consequently,MOF-PDA exhibited the highly effective antibacterial efficacy of 99.62%and 99.97%against Staphylococcus aureus and Escherichia coli,respectively,under 20 min 660 nm light irradiation.     

Formation of willow leaf-like structures composed of NH2-MIL68(In) on a multifunctional multiwalled carbon nanotube backbone for enhanced photocatalytic reduction of Cr(VI)

Efficient separation and transfer of photogenerated electron/hole as well as enhanced visible light absorption play essential roles in photocatalytic reactions.To promote the photocatalytic reduction of Cr(Ⅵ),a toxic heavy metal ion,multiwalled carbon nanotube (MWCNT) was introduced as an electron acceptor into NH2-MIL-68(In).This led to the growth of a willow leaf-like metal-organic framework (MOF) on an MWCNT backbone forming MWCNT/NH2-MIL-68(In)(PL-1),which showed a highly efficient transfer of photogenerated carriers.Moreover,MWCNT incorporation introduced more mesopores for Cr(Ⅵ) diffusion and enhanced the visible light adsorption without lowering the conduction band position.As a result,the photocatalytic kinetic constant of PL-1 was found to be almost three times higher than that of the parent NH2-MIL-68(In).Thus,growing MOFs on MWCNTs provides a facile and promising solution for effective remediation of environmental pollution by utilizing solar energy.This work provides the first example of using MWCNT/MOF composites for photocatalytic reactions.