Modification of nickel sulfide cocatalysts is considered to be a promising approach for efficient enhancement of the photocatalytic hydrogen production performance of g-C3N4.Providing more NiS cocatalyst to function a...Modification of nickel sulfide cocatalysts is considered to be a promising approach for efficient enhancement of the photocatalytic hydrogen production performance of g-C3N4.Providing more NiS cocatalyst to function as active sites of g-C3N4 is still highly desirable.To realize this goal,in this work,a facile sulfur-mediated photodeposition approach was developed.Specifically,photogenerated electrons excited by visible light reduce the S molecules absorbed on g-C3N4 surface to S^2‒,and subsequently NiS cocatalyst is formed in situ on the g-C3N4 surface by a combination of Ni2+and S2‒due to their small solubility product constant(Ksp=3.2×10^‒19).This approach has several advantages.The NiS cocatalyst is clearly in situ deposited on the photogenerated electron transfer sites of g-C3N4,and thus provides more active sites for H2 production.In addition,this method utilizes solar energy with mild reaction conditions at room temperature.Consequently,the synthesized NiS/g-C3N4 photocatalyst achieves excellent hydrogen generation performance with the performance of the optimal sample(244μmol h^‒1 g^‒1)close to that of 1 wt%Pt/g-C3N4(316μmol h^‒1 g^‒1,a well-known excellent photocatalyst).More importantly,the present sulfur-mediated photodeposition route is versatile and facile and can be used to deposit various metal sulfides such as CoSx,CuSx and AgSx on the g-C3N4 surface,and all the resulting metal sulfide-modified g-C3N4 photocatalysts exhibit improved H2-production performance.Our study offers a novel insight for the synthesis of high-efficiency photocatalysts.展开更多
The ternary plasmonic Ag Cl/Ag/g-C_3N_4 photocatalysts were successfully fabricated by a modified deposition–precipitation method, through which Ag/Ag Cl nanoparticles(5–15 nm in size) were evenly dispersed on the s...The ternary plasmonic Ag Cl/Ag/g-C_3N_4 photocatalysts were successfully fabricated by a modified deposition–precipitation method, through which Ag/Ag Cl nanoparticles(5–15 nm in size) were evenly dispersed on the surface of g-C_3N_4. The Ag Cl/Ag/g-C_3N_4 composites exhibited higher photocatalytic activity than Ag/Ag Cl and g-C_3N_4. The enhanced photocatalytic performance could be attributed to an efficient separation of electron–hole pairs through a Z-scheme mechanism, in which Ag nanoparticles acted as charge separation centers.展开更多
Bi_2WO_6 was modified by two-dimensional g-C_3N_4(2D g-C_3N_4)via a hydrothermal method.The structure,morphology,optical and electronic properties were investigated by multiple techniques,including X-ray diffraction(X...Bi_2WO_6 was modified by two-dimensional g-C_3N_4(2D g-C_3N_4)via a hydrothermal method.The structure,morphology,optical and electronic properties were investigated by multiple techniques,including X-ray diffraction(XRD),X-ray photoelectron spectroscopy spectra(XPS),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Ultravioletvisible diffuse reflection spectroscopy(DRS),photocurrent and electrochemical impedance spectroscopy(EIS),electron spin resonance(ESR),respectively.Rhodamine B(Rh B)was used as the target organic pollutant to research the photocatalytic performance of as-prepared composites.The Bi_2WO_6/2D g-C_3N_4exhibited a remarkable improvement compared with the pure Bi_2WO_6.The enhanced photocatalytic activity was because the photogenerated electrons and holes can quickly separate by Z-Scheme passageway in composites.The photocatalytic mechanism was also researched in detail through ESR analysis.展开更多
Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as ...Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.展开更多
采用浸渍法制备不同负载量NiFe_2O_4的负载型光催化剂NiFe_2O_4/g-C_3N_4,利用XRD、FT-IR、N_2-adsorption、ICP-OES、TEM及XPS等手段表征NiFe_2O_4/g-C_3N_4样品,并考察其对甲基橙的可见光催化降解性能。结果表明,与NiFe_2O_4和g-C3N4...采用浸渍法制备不同负载量NiFe_2O_4的负载型光催化剂NiFe_2O_4/g-C_3N_4,利用XRD、FT-IR、N_2-adsorption、ICP-OES、TEM及XPS等手段表征NiFe_2O_4/g-C_3N_4样品,并考察其对甲基橙的可见光催化降解性能。结果表明,与NiFe_2O_4和g-C3N4样品相比,负载型NiFe_2O_4/g-C_3N_4样品对甲基橙具有更好的光催化降解活性,且催化活性随着NiFe_2O_4负载量增大(0.5~5.0wt%)而呈现先增大再减小的趋势。NiFe_2O_4负载量2.0wt%的样品2-Ni Fe/CN在可见光照射下对浓度5 mg·L^(-1)的甲基橙表现出最好的降解活性和稳定性。这是因为能带宽度小(1.5 e V)的NiFe_2O_4与能带宽度大(2.7 e V)的g-C_3N_4形成的异质结催化剂NiFe_2O_4/g-C_3N_4,有效地促进光生载流子在二者界面快速传递和光生电子-空穴对的有效分离。展开更多
文摘Modification of nickel sulfide cocatalysts is considered to be a promising approach for efficient enhancement of the photocatalytic hydrogen production performance of g-C3N4.Providing more NiS cocatalyst to function as active sites of g-C3N4 is still highly desirable.To realize this goal,in this work,a facile sulfur-mediated photodeposition approach was developed.Specifically,photogenerated electrons excited by visible light reduce the S molecules absorbed on g-C3N4 surface to S^2‒,and subsequently NiS cocatalyst is formed in situ on the g-C3N4 surface by a combination of Ni2+and S2‒due to their small solubility product constant(Ksp=3.2×10^‒19).This approach has several advantages.The NiS cocatalyst is clearly in situ deposited on the photogenerated electron transfer sites of g-C3N4,and thus provides more active sites for H2 production.In addition,this method utilizes solar energy with mild reaction conditions at room temperature.Consequently,the synthesized NiS/g-C3N4 photocatalyst achieves excellent hydrogen generation performance with the performance of the optimal sample(244μmol h^‒1 g^‒1)close to that of 1 wt%Pt/g-C3N4(316μmol h^‒1 g^‒1,a well-known excellent photocatalyst).More importantly,the present sulfur-mediated photodeposition route is versatile and facile and can be used to deposit various metal sulfides such as CoSx,CuSx and AgSx on the g-C3N4 surface,and all the resulting metal sulfide-modified g-C3N4 photocatalysts exhibit improved H2-production performance.Our study offers a novel insight for the synthesis of high-efficiency photocatalysts.
基金financial aid from the National Natural Science Foundation of China(NSFC No.51472133)
文摘The ternary plasmonic Ag Cl/Ag/g-C_3N_4 photocatalysts were successfully fabricated by a modified deposition–precipitation method, through which Ag/Ag Cl nanoparticles(5–15 nm in size) were evenly dispersed on the surface of g-C_3N_4. The Ag Cl/Ag/g-C_3N_4 composites exhibited higher photocatalytic activity than Ag/Ag Cl and g-C_3N_4. The enhanced photocatalytic performance could be attributed to an efficient separation of electron–hole pairs through a Z-scheme mechanism, in which Ag nanoparticles acted as charge separation centers.
基金supported by National Nature Science Foundation of China (21476097, 21776118)Six talent peaks project in Jiangsu Province (2014-JNHB-014)Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Bi_2WO_6 was modified by two-dimensional g-C_3N_4(2D g-C_3N_4)via a hydrothermal method.The structure,morphology,optical and electronic properties were investigated by multiple techniques,including X-ray diffraction(XRD),X-ray photoelectron spectroscopy spectra(XPS),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Ultravioletvisible diffuse reflection spectroscopy(DRS),photocurrent and electrochemical impedance spectroscopy(EIS),electron spin resonance(ESR),respectively.Rhodamine B(Rh B)was used as the target organic pollutant to research the photocatalytic performance of as-prepared composites.The Bi_2WO_6/2D g-C_3N_4exhibited a remarkable improvement compared with the pure Bi_2WO_6.The enhanced photocatalytic activity was because the photogenerated electrons and holes can quickly separate by Z-Scheme passageway in composites.The photocatalytic mechanism was also researched in detail through ESR analysis.
基金supported by the National Natural Science Foundation of China (51672089)the Industry and Research Collaborative Innovation Major Projects of Guangzhou (201508020098)+1 种基金the State Key Laboratory of Advanced Technology for Material Synthesis and Processing (Wuhan University of Technology) (2015-KF-7)the Hunan Key Laboratory of Applied Environmental Photocatalysis (Changsha University) (CCSU-XT-04)~~
文摘Novel WO3/g-C3N4/Ni（OH）x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition.Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation.The loading of WO3 and Ni（OH）x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4.WO3/g-C3N4/Ni（OH）x with 20 wt%defective WO3 and 4.8 wt%Ni（OH）x showed the highest hydrogen production rate of 576 μmol/（g·h）,which was 5.7,10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni（OH）x,20 wt%WO3/C3N4 and g-C3N4 photocatalysts,respectively.The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction（WO3/g-C3N4） and loaded cocatalysts（Ni（OH）x）,which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics.The electron spin resonance spectra of ·O2^- and ·OH radicals provided evidence for the Z-scheme charge separation mechanism.The loading of easily available Ni（OH）x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.
文摘采用浸渍法制备不同负载量NiFe_2O_4的负载型光催化剂NiFe_2O_4/g-C_3N_4,利用XRD、FT-IR、N_2-adsorption、ICP-OES、TEM及XPS等手段表征NiFe_2O_4/g-C_3N_4样品,并考察其对甲基橙的可见光催化降解性能。结果表明,与NiFe_2O_4和g-C3N4样品相比,负载型NiFe_2O_4/g-C_3N_4样品对甲基橙具有更好的光催化降解活性,且催化活性随着NiFe_2O_4负载量增大(0.5~5.0wt%)而呈现先增大再减小的趋势。NiFe_2O_4负载量2.0wt%的样品2-Ni Fe/CN在可见光照射下对浓度5 mg·L^(-1)的甲基橙表现出最好的降解活性和稳定性。这是因为能带宽度小(1.5 e V)的NiFe_2O_4与能带宽度大(2.7 e V)的g-C_3N_4形成的异质结催化剂NiFe_2O_4/g-C_3N_4,有效地促进光生载流子在二者界面快速传递和光生电子-空穴对的有效分离。
