Photocatalytic nitrogen fixation has been explored as a feasible pathway for ammonia synthesis.How-ever,the convenient and efficient preparation of photocatalysts for nitrogen fixation remains a challenge.Meanwhile,th...Photocatalytic nitrogen fixation has been explored as a feasible pathway for ammonia synthesis.How-ever,the convenient and efficient preparation of photocatalysts for nitrogen fixation remains a challenge.Meanwhile,the reaction pathway and mechanism of photocatalytic nitrogen fixation are unclear.Herein,single-atom Fe-porous g-C_(3)N_(4)(FPx)samples were manufactured using a one-step anneal technique via bubble template and direct metal atomization.Characterization results indicate that FPx has a porous structure and single-atom Fe.The porous structure exposed more active centers.Simultaneously,single-atom Fe changes the adsorption mode of N_(2)from physical to chemical and turns the photocatalytic ni-trogen fixation from the associative distal pathway to the associative alternating pathway.Consequently,without any sacrificial agent or cocatalysts,FPx presents a prominent increase in photocatalytic activ-ity,reaching 62.42μmol h^(−1)g^(−1),over fivefold larger than that of bulk g-C_(3)N_(4).This work provides new insights into photocatalytic nitrogen fixation and achieves efficient N_(2)photoreduction by constructing single-atom photocatalysts.展开更多
In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)an...In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)and the Ag_(2)S content were optimized. The best 0.5% Ag_(2)S/KTa_(0.5)Nb_(0.5)O_(3)(KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag_(2)S. Under simulated sunlight, the NH_(3)generation rate of 0.5% Ag_(2)S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0.XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag_(2)S/KTN heterojunction established a type-Ⅱ band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag_(2)S/KTN composite exhibited higher NH3generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.展开更多
The porous few-layer g-C_(3)N_(4)(PFL-g-C_(3)N_(4))is prepared by a simple molecular self-assembly method.Compared with pure g-C_(3)N_(4),the as-prepared PFL-g-C_(3)N_(4) is ultrathin,the surface is rich in pores,and ...The porous few-layer g-C_(3)N_(4)(PFL-g-C_(3)N_(4))is prepared by a simple molecular self-assembly method.Compared with pure g-C_(3)N_(4),the as-prepared PFL-g-C_(3)N_(4) is ultrathin,the surface is rich in pores,and the photocatalytic nitrogen fixation activity is greatly increased to 8.20 mM h^(-1) gCat^(-1).Few-layer and ultrathin nature of PFL-g-C_(3)N_(4) can provide a larger specific surface area,expose more active sites,and reduce the diffusion path of charges and protons from the inside to the surface.In addition,the porous structure can narrow the band gap,thereby increasing the light absorption range and enhancing the light absorption capability.Meanwhile,the presence of nitrogen vacancies causes PFL-g-C_(3)N_(4) to move to a more negative conductive band value.More importantly,the isotopic experiments using ^(15)N_(2) as nitrogen source confirm the ammonia production originating from N2 rather than the decomposition of g-C_(3)N_(4).Therefore,PFL-g-C_(3)N_(4) can greatly improve the efficiency of visible light photocatalytic nitrogen fixation.展开更多
Solar driven nitrogen(N_(2))fixation to synthesize ammonia is a potential alternative for the traditional Haber-Bosch approach to meeting industrial demand,but is largely hampered by the difficulties in the harvesting...Solar driven nitrogen(N_(2))fixation to synthesize ammonia is a potential alternative for the traditional Haber-Bosch approach to meeting industrial demand,but is largely hampered by the difficulties in the harvesting of solar energy and activating inert N_(2).In this work,hollow CeF_(3) nanospheres co-doped with activator Tm^(3+)and sensitizer Yb^(3+)(Yb^(3+):Tm^(3+):CeF_(3))were prepared by microwave hydrothermal method.The product was employed as a catalyst for photo-driven N_(2) fixation by adjusting the molar ratio of Ce^(3+):Yb^(3+):Tm^(3+).Results show that the porous hollow structure enhances the light-harvesting by physical scattering and reflection.In addition,heteroatom doping generates abundant fluorine vacancies(F_(V))which provide abundant active sites for adsorption and activation of N_(2).The sample with molar ratio of CeF_(3):Yb^(3+):Tm^(3+)at 178:20:2 demonstrates the highest utilization of solar energy attributed to the strongest upconversion capability of near-infrared(NIR)light to visible and ultraviolet(UV)light,and the NH_(4)+concentration achieves the highest value of 15.06μmol/(gcat∙h)under simulated sunlight while nearly 6.22μmol/(gcat∙h)under NIR light.Current study offers a promising and sustainable strategy for the fixation of atmospheric N_(2) using full-spectrum solar energy.展开更多
As is known to all, nitrogen not only plays an important role in the industrial development of human society but also plays an important part in the proteins that constitute the essence of life[1]. In 1910, the Haber-...As is known to all, nitrogen not only plays an important role in the industrial development of human society but also plays an important part in the proteins that constitute the essence of life[1]. In 1910, the Haber-Bosch process was first used to synthesize ammonia.展开更多
基金supported by the Jiangxi Provincial Natural Science Foundation(No.20224BAB213016)Jiangxi Province tech-nology innovation guidance project(grant No.20212BDH81036)Science and Technology Project of the Education Department of Jiangxi Province(No.GJJ200457).
文摘Photocatalytic nitrogen fixation has been explored as a feasible pathway for ammonia synthesis.How-ever,the convenient and efficient preparation of photocatalysts for nitrogen fixation remains a challenge.Meanwhile,the reaction pathway and mechanism of photocatalytic nitrogen fixation are unclear.Herein,single-atom Fe-porous g-C_(3)N_(4)(FPx)samples were manufactured using a one-step anneal technique via bubble template and direct metal atomization.Characterization results indicate that FPx has a porous structure and single-atom Fe.The porous structure exposed more active centers.Simultaneously,single-atom Fe changes the adsorption mode of N_(2)from physical to chemical and turns the photocatalytic ni-trogen fixation from the associative distal pathway to the associative alternating pathway.Consequently,without any sacrificial agent or cocatalysts,FPx presents a prominent increase in photocatalytic activ-ity,reaching 62.42μmol h^(−1)g^(−1),over fivefold larger than that of bulk g-C_(3)N_(4).This work provides new insights into photocatalytic nitrogen fixation and achieves efficient N_(2)photoreduction by constructing single-atom photocatalysts.
基金financially supported by National Natural Science Foundation of China (Grant No. 22172144)Nature Science Foundation of Zhejiang Province (Grant No. LY20B030004)。
文摘In this work, a novel heterojunction composite Ag_(2)S/KTa_(x)Nb_(1-x)O_(3)was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTa_(x)Nb_(1-x)O_(3)and the Ag_(2)S content were optimized. The best 0.5% Ag_(2)S/KTa_(0.5)Nb_(0.5)O_(3)(KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag_(2)S. Under simulated sunlight, the NH_(3)generation rate of 0.5% Ag_(2)S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0.XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag_(2)S/KTN heterojunction established a type-Ⅱ band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag_(2)S/KTN composite exhibited higher NH3generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.
基金fundings from the National Natural Science Foundation of China(No.51872173 and 51772167)Taishan Scholarship of Young Scholars(No.tsqn201812068)+3 种基金Taishan Scholarship of Climbing Plan(No.tspd20161006)Key Research and Development Program of Shandong Province(No.2018GGX102028)Natural Science Foundation of Shandong Province(No.ZR2017JL020)Higher School Youth Innovation Team of Shandong Province(No.2019KJA013).
文摘The porous few-layer g-C_(3)N_(4)(PFL-g-C_(3)N_(4))is prepared by a simple molecular self-assembly method.Compared with pure g-C_(3)N_(4),the as-prepared PFL-g-C_(3)N_(4) is ultrathin,the surface is rich in pores,and the photocatalytic nitrogen fixation activity is greatly increased to 8.20 mM h^(-1) gCat^(-1).Few-layer and ultrathin nature of PFL-g-C_(3)N_(4) can provide a larger specific surface area,expose more active sites,and reduce the diffusion path of charges and protons from the inside to the surface.In addition,the porous structure can narrow the band gap,thereby increasing the light absorption range and enhancing the light absorption capability.Meanwhile,the presence of nitrogen vacancies causes PFL-g-C_(3)N_(4) to move to a more negative conductive band value.More importantly,the isotopic experiments using ^(15)N_(2) as nitrogen source confirm the ammonia production originating from N2 rather than the decomposition of g-C_(3)N_(4).Therefore,PFL-g-C_(3)N_(4) can greatly improve the efficiency of visible light photocatalytic nitrogen fixation.
基金Project supported by the National Natural Science Foundation of China (51674043,51702026)。
文摘Solar driven nitrogen(N_(2))fixation to synthesize ammonia is a potential alternative for the traditional Haber-Bosch approach to meeting industrial demand,but is largely hampered by the difficulties in the harvesting of solar energy and activating inert N_(2).In this work,hollow CeF_(3) nanospheres co-doped with activator Tm^(3+)and sensitizer Yb^(3+)(Yb^(3+):Tm^(3+):CeF_(3))were prepared by microwave hydrothermal method.The product was employed as a catalyst for photo-driven N_(2) fixation by adjusting the molar ratio of Ce^(3+):Yb^(3+):Tm^(3+).Results show that the porous hollow structure enhances the light-harvesting by physical scattering and reflection.In addition,heteroatom doping generates abundant fluorine vacancies(F_(V))which provide abundant active sites for adsorption and activation of N_(2).The sample with molar ratio of CeF_(3):Yb^(3+):Tm^(3+)at 178:20:2 demonstrates the highest utilization of solar energy attributed to the strongest upconversion capability of near-infrared(NIR)light to visible and ultraviolet(UV)light,and the NH_(4)+concentration achieves the highest value of 15.06μmol/(gcat∙h)under simulated sunlight while nearly 6.22μmol/(gcat∙h)under NIR light.Current study offers a promising and sustainable strategy for the fixation of atmospheric N_(2) using full-spectrum solar energy.
基金supported by the National Key R&D Program of China(2017YFA0208300 and 2017YFA0700104)the National Natural Science Foundation of China(21671180 and 21406184)+2 种基金the Chengdu International Science and Technology Cooperation Fund(2020GH0200069HZ)the funding support from CAS Fujian Institute of Innovationfinancially supported by the DNL Cooperation Fund(DNL201918)。
文摘As is known to all, nitrogen not only plays an important role in the industrial development of human society but also plays an important part in the proteins that constitute the essence of life[1]. In 1910, the Haber-Bosch process was first used to synthesize ammonia.
