Single-atom catalysts based on graphitic carbon nitride(g-C_(3)N_(4))show high potential for hydrogen production photocatalytically.However,it is still a challenge to develop single-atom-based g-C_(3)N_(4)due to the c...Single-atom catalysts based on graphitic carbon nitride(g-C_(3)N_(4))show high potential for hydrogen production photocatalytically.However,it is still a challenge to develop single-atom-based g-C_(3)N_(4)due to the complex synthesis procedures,limited active sites,and insufficient mechanistic understanding.Herein,a facile oxygen-tolerant synthesis strategy was developed,which utilizes the nitrogen-rich structure of g-C_(3)N_(4)to capture Fe single atoms from ammonium iron citrate,successfully constructing an efficient photocatalytic composite.The resulting Fe single-atom-modified g-C_(3)N_(4)catalyst exhibited highly improved light absorption,charge carrier separation,and a substantially enhanced rate of H_(2)production photocatalytically under visible light irradiation.Experimental results demonstrated that the optimal sample achieves a H_(2)production rate of 683μmol·h-1·g^(-1),representing a 425% enhancement compared to pristine g-C_(3)N_(4).This study presents a facile oxygen-tolerant approach for metal immobilization using metal-organic precursors,where the nitrogen-rich framework of g-C_(3)N_(4)effectively captures Fe atoms as singular site within the composite.The developed synthesis strategy provides new insights for designing high-performance single-atom photocatalytic materials,potentially advancing the application and development of photocatalysis.展开更多
Propylene,a readily accessible and economically viable light olefin,has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes.The distribution of pro...Propylene,a readily accessible and economically viable light olefin,has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes.The distribution of products is profoundly influenced by the catalyst structure.In this study,Fe_(2)O_(3)-doped NiSO_(4)/Al_(2)O_(3) catalysts have been meticulously developed to facilitate the selective trimerization of propylene under mild conditions.Significantly,the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst demonstrates an enhanced reaction rate(48.5 mmol_(C3)/(g_(cat).·h)),alongside a high yield of C9(~32.2%),significantly surpassing the performance of the NiSO_(4)/Al_(2)O_(3) catalyst(C9:~24.1%).The incorporation of Fe_(2)O_(3) modifies the migration process of sulfate ions,altering the Lewis acidity of the electron-deficient Ni and Fe sites on the catalyst and resulting a shift in product distribution from a Schulz-Flory distribution to a Poisson distribution.This shift is primarily ascribed to the heightened energy barrier for theβ-H elimination reaction in the C6 alkyl intermediates on the doped catalyst,further promoting polymerization to yield a greater quantity of Type II C9.Furthermore,the validation of the Cossee-Arlman mechanism within the reaction pathway has been confirmed.It is noteworthy that the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst exhibits remarkable stability exceeding 80 h in the selective trimerization of propylene.These research findings significantly enhance our understanding of the mechanisms underlying olefin oligomerization reactions and provide invaluable insights for the development of more effective catalysts.展开更多
为探讨堆肥初始物料对腐熟堆肥溶解性有机质(DOM)的Fe^(3+)生物还原强化效应的影响,本研究提取了不同物料腐熟堆肥(包括猪粪PM、鸡粪CM、蚕沙SE、木薯渣CR、厨余垃圾KW、污泥SS)及泥炭土(PS)的DOM,分析其光谱特征(紫外光谱、红外光谱和...为探讨堆肥初始物料对腐熟堆肥溶解性有机质(DOM)的Fe^(3+)生物还原强化效应的影响,本研究提取了不同物料腐熟堆肥(包括猪粪PM、鸡粪CM、蚕沙SE、木薯渣CR、厨余垃圾KW、污泥SS)及泥炭土(PS)的DOM,分析其光谱特征(紫外光谱、红外光谱和三维荧光光谱)、电子转移能力(ETC)及Fe^(3+)生物还原强化效果。结果表明:PM、CM、SE和SS中DOM含有更多的芳香结构、醌基官能团和更少的类木质素含量;CR中DOM含有更多的微生物类腐殖质组分(C2),CM和SS中DOM含有更多的类色氨酸组分(C4);6种物料堆肥DOM的电子转移能力总体略低于PS(EAC+EDC,628.42~720.57µmol·g^(-1)vs 710.37µmol·g^(-1)),其中SE>PM>CR>KW>CM>SS;SS、CM和SE中DOM在0~2 d内对Fe^(3+)的还原速率有显著的促进作用,相比于空白处理组分别提高了31.57、25.39倍和22.60倍;相关性分析表明,SUVA_(254)×C4、SUVA_(436)×C4指标与0~2 d Fe^(3+)还原速率呈显著性正相关(P=0.05),而类木质素含量与之呈显著负相关。SS、CM和SE物料的腐熟堆肥具有较多醌类结构的类色氨酸组分,使其具有较高的在Fe^(3+)/Fe^(2+)和希瓦氏菌MR-1之间的电子转移能力,从而提高Fe^(3+)生物还原强化效应。展开更多
基金financially supported by the National Natural Science Foundation of China(No.22272159)the Chinese Academy of Sciences(No.KFJ-XCZX-202304).
文摘Single-atom catalysts based on graphitic carbon nitride(g-C_(3)N_(4))show high potential for hydrogen production photocatalytically.However,it is still a challenge to develop single-atom-based g-C_(3)N_(4)due to the complex synthesis procedures,limited active sites,and insufficient mechanistic understanding.Herein,a facile oxygen-tolerant synthesis strategy was developed,which utilizes the nitrogen-rich structure of g-C_(3)N_(4)to capture Fe single atoms from ammonium iron citrate,successfully constructing an efficient photocatalytic composite.The resulting Fe single-atom-modified g-C_(3)N_(4)catalyst exhibited highly improved light absorption,charge carrier separation,and a substantially enhanced rate of H_(2)production photocatalytically under visible light irradiation.Experimental results demonstrated that the optimal sample achieves a H_(2)production rate of 683μmol·h-1·g^(-1),representing a 425% enhancement compared to pristine g-C_(3)N_(4).This study presents a facile oxygen-tolerant approach for metal immobilization using metal-organic precursors,where the nitrogen-rich framework of g-C_(3)N_(4)effectively captures Fe atoms as singular site within the composite.The developed synthesis strategy provides new insights for designing high-performance single-atom photocatalytic materials,potentially advancing the application and development of photocatalysis.
文摘Propylene,a readily accessible and economically viable light olefin,has garnered substantial interest for its potential conversion into valuable higher olefins through oligomerization processes.The distribution of products is profoundly influenced by the catalyst structure.In this study,Fe_(2)O_(3)-doped NiSO_(4)/Al_(2)O_(3) catalysts have been meticulously developed to facilitate the selective trimerization of propylene under mild conditions.Significantly,the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst demonstrates an enhanced reaction rate(48.5 mmol_(C3)/(g_(cat).·h)),alongside a high yield of C9(~32.2%),significantly surpassing the performance of the NiSO_(4)/Al_(2)O_(3) catalyst(C9:~24.1%).The incorporation of Fe_(2)O_(3) modifies the migration process of sulfate ions,altering the Lewis acidity of the electron-deficient Ni and Fe sites on the catalyst and resulting a shift in product distribution from a Schulz-Flory distribution to a Poisson distribution.This shift is primarily ascribed to the heightened energy barrier for theβ-H elimination reaction in the C6 alkyl intermediates on the doped catalyst,further promoting polymerization to yield a greater quantity of Type II C9.Furthermore,the validation of the Cossee-Arlman mechanism within the reaction pathway has been confirmed.It is noteworthy that the 0.25Fe_(2)O_(3)-NiSO_(4)/Al_(2)O_(3) catalyst exhibits remarkable stability exceeding 80 h in the selective trimerization of propylene.These research findings significantly enhance our understanding of the mechanisms underlying olefin oligomerization reactions and provide invaluable insights for the development of more effective catalysts.
文摘为探讨堆肥初始物料对腐熟堆肥溶解性有机质(DOM)的Fe^(3+)生物还原强化效应的影响,本研究提取了不同物料腐熟堆肥(包括猪粪PM、鸡粪CM、蚕沙SE、木薯渣CR、厨余垃圾KW、污泥SS)及泥炭土(PS)的DOM,分析其光谱特征(紫外光谱、红外光谱和三维荧光光谱)、电子转移能力(ETC)及Fe^(3+)生物还原强化效果。结果表明:PM、CM、SE和SS中DOM含有更多的芳香结构、醌基官能团和更少的类木质素含量;CR中DOM含有更多的微生物类腐殖质组分(C2),CM和SS中DOM含有更多的类色氨酸组分(C4);6种物料堆肥DOM的电子转移能力总体略低于PS(EAC+EDC,628.42~720.57µmol·g^(-1)vs 710.37µmol·g^(-1)),其中SE>PM>CR>KW>CM>SS;SS、CM和SE中DOM在0~2 d内对Fe^(3+)的还原速率有显著的促进作用,相比于空白处理组分别提高了31.57、25.39倍和22.60倍;相关性分析表明,SUVA_(254)×C4、SUVA_(436)×C4指标与0~2 d Fe^(3+)还原速率呈显著性正相关(P=0.05),而类木质素含量与之呈显著负相关。SS、CM和SE物料的腐熟堆肥具有较多醌类结构的类色氨酸组分,使其具有较高的在Fe^(3+)/Fe^(2+)和希瓦氏菌MR-1之间的电子转移能力,从而提高Fe^(3+)生物还原强化效应。
