制备了不同阳离子掺杂改性的针铁矿,并采用XRD、红外、热重差热分析以及TEM等手段对其进行了表征,结果显示,掺入Mn^(2+)、Cr^(3+)、Al^(3+)后并未明显改变α-FeOOH的晶体结构类型,说明部分阳离子掺杂进入α-FeOOH晶格,从而分别形成因Fe^...制备了不同阳离子掺杂改性的针铁矿,并采用XRD、红外、热重差热分析以及TEM等手段对其进行了表征,结果显示,掺入Mn^(2+)、Cr^(3+)、Al^(3+)后并未明显改变α-FeOOH的晶体结构类型,说明部分阳离子掺杂进入α-FeOOH晶格,从而分别形成因Fe^(3+)被Mn^(2+)、Cr^(3+)、Al^(3+)部分取代的固溶体;红外分析也得到类似结果;热重和差热分析以及TEM观察结果均表明几种金属阳离子没有形成氧化物相,可以确定这些离子已经进入针铁矿的晶格;紫外-可见漫反射光谱分析发现Mn^(2+)、Cr^(3+)掺杂者的能带隙较之纯相针铁矿的稍小,依次为2.18 e V和2.24 e V;而Al^(3+)掺杂者的能带隙与纯相针铁矿相比有所提高,增加至2.34 e V。此外还考查了不同阳离子掺杂及纯相针铁矿与Fe(Ⅱ)构成的复合系统对邻硝基苯酚(2-NP)的还原效果,研究表明,在溶液pH=6和25℃等的条件下,上述还原转化反应符合准一级动力学方程。其中,Fe(Ⅱ)/Al^(3+)掺杂针铁矿复合系统对2-NP的降解效果最好,在120 min时就达到了100%去除率,在一定浓度范围内,随着2-NP浓度的升高,2-NP的还原速率降低。而且,Fe(Ⅱ)/Al^(3+)-针铁矿复合系统速率常数(k)随着溶液的pH值增大而升高。展开更多
Palladium-supported cobalt hydroxide(Co(OH)_(2)-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol.For the preparation of Co(OH)2-Pd,Pd nanoparticles we...Palladium-supported cobalt hydroxide(Co(OH)_(2)-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol.For the preparation of Co(OH)2-Pd,Pd nanoparticles were anchored on the Co(OH)_(2) nanoplates after the reduction of Na;PdCl;by ascorbic acid in the absence of a stabilizer at room temperature.The observations under transmission and scanning electron microscopy reveal that Pd nanoparticles with a size of 2-5 nm are uniformly dispersed on the surface of the Co(OH)_(2) nanoplates.In catalytic test,the conversion of 4-nitrophenol to 4-aminophenol is completed within 6 min in the presence of Co(OH)_(2)-Pd(1000) nanoplates with2.18 at.% Pd,and the corresponding kinetic constant is 0.0089 s;in the first test.The catalyst retains relatively high activity after several cycles.The results demonstrate that the Co(OH)_(2)-Pd(1000) nanoplates exhibit high catalytic activity toward the reduction of 4-nitrophenol in the presence of NaBH;.展开更多
Cu2O@Cu nanocomposite was prepared by a simple high temperature calcination reaction in N2 atmosphere.The as-prepared samples were characterized by XRD,SEM and TEM,which indicated that the product formed by nano-sheet...Cu2O@Cu nanocomposite was prepared by a simple high temperature calcination reaction in N2 atmosphere.The as-prepared samples were characterized by XRD,SEM and TEM,which indicated that the product formed by nano-sheets stacking had a high specific surface area.The as-synthesized material shows efficient catalytic activity for the reduction of organic compound in aqueous medium,in which 4-nitrophenol can be reduced to p-aminophenol and Congo red can be degraded to colorless solution.展开更多
Toward the imperative treatment of the industrial wastewater containing 4-nitrophenol(4-NP)and industrial solid waste red mud(RM),an innovative approach of“Using waste to treat waste”is developed.Valuable element Al...Toward the imperative treatment of the industrial wastewater containing 4-nitrophenol(4-NP)and industrial solid waste red mud(RM),an innovative approach of“Using waste to treat waste”is developed.Valuable element Al is leached from the RM first,the resultant NaAlO_(2) solution is hydrothermally converted toγ-AlOOH hierarchical porous microspheres(RMγ-AlOOH HPMSs,average diameter:2.0μm,SBET:77.81 m^(2) g^(-1),pore volume:0.38 cm^(3) g^(-1))in the presence of urea.The subsequent mild thermal conversion results inγ-Al_(2)O_(3) hierarchical porous microspheres(RMγ-Al_(2)O_(3) HPMSs).Both of the RMγ-AlOOH and RMγ-Al_(2)O_(3) HPMSs are employed as the Pd catalyst support for the catalytic reduction of 4-NP.Particularly,the as-obtained composite Pd/RMγ-AlOOH and Pd/RMγ-Al_(2)O_(3) exhibit excellent catalytic activities with superior knor as 8204.5 and 4831.4 s^(-1) g^(-1),respectively,significantly higher than that of most Pd based catalysts.Moreover,the excellent catalytic stability and durability of the Pd/RMγ-AlOOH and Pd/RMγ-Al_(2)O_(3) within 10 successive cycles of reduction enable the present industrial solid waste RM inducedγ-AlOOH andγ-Al_(2)O_(3) HPMSs as great promising Pd catalyst support for the reduction of the industrial wastewater containing 4-NP.展开更多
The development of effective catalysts for the catalytic conversion of the harmful nitrophenol （NP） into the useful aminophenol （AP） has received extensive interest. Herein, we report the easy and large-scale synt...The development of effective catalysts for the catalytic conversion of the harmful nitrophenol （NP） into the useful aminophenol （AP） has received extensive interest. Herein, we report the easy and large-scale synthesis of strongly coupled Ag/TiO2 heterojunctions based on the coordinated action of organic components with a multi-kind metal precursor. The heterojunctions were effective and stable catalysts for the photothermal catalytic reduction of 4-NP to 4-AP. In the synthesis, critic acid, ethylene glycol AgNO3, and tetrabutyl titanate were dissolved and coordinated in water. Under heating, a precursor gel having a uniform distribution of Ag and Ti was gradually formed. Via calcination in air, the Ti precursor was transformed into TiO2, accompanied by the reduction of Ag＋ to Ag nanoparticles. The formation of Ag/TiO2 composites with intimate interface contact benefited from the uniform distribution of different components in the precursor gel. The Ag/TiO2 functioned as an effective catalyst for the reduction of 4-NP, exhibiting higher activity than the many reported Ag-based catalysts. The catalytic reaction over Ag/TiO2 had a small to with good activity and reuse performance. After 10 cycles of reuse, the conversion efficiency exhibited no obvious change. Importantly, the conversion of 4-NP was significantly enhanced under light irradiation provided by a 150-W Xe lamp （the visible light from cutoff have equal function）, but ultraviolet light did not promote the conversion. The conversion time was reduced from 620 to 270 s with light irradiation （15 ~C）. The reaction rate under light irradiation （0.014 s-1） was approximately three times higher than that in the dark at 15 ~C （0.0044 s-1） and even better than that in the dark at 25 ~C （0.01 s-l）. A series of experiments indicated that the light irradiation promoted the conversion of 4-NP because of the localized surface plasmon resonance effect of Ag, which generated hot e- and h~ particles and local heating around the particles via their absorption of the light.展开更多
Catalytic degradation of organic contaminants is at the frontier of water treatment due to its selectivity,energy savings,and ability to convert harmful contaminants into harmless or even valuable chemical products fo...Catalytic degradation of organic contaminants is at the frontier of water treatment due to its selectivity,energy savings,and ability to convert harmful contaminants into harmless or even valuable chemical products for recycling.However,achieving sufficiently high performance in the catalytic removal of organic contaminants for practical application is still extremely challenging.Herein,we report a Pd-decorated TiO_(2)(Pd/TiO_(2))hierarchical vertical array for fast and efficient catalytic water treatment.Such a forest-like Pd/TiO_(2) vertical array demonstrates the following distinct advantages over conventional planar or bulk catalytic systems:1)abundant anchoring sites for nanocrystals loading;2)high sunlight absorption;3)efficient mass transfer channels for the reactants and products.As a proof of concept,the Pd/TiO_(2) array demonstrated rapid and efficient photo-assisted catalytic reduction of high concentrations of 4-nitrophenol wastewater(2 g/L,ca.14.38 mmol/L)and its feasibility for continuous flow wastewater treatment.The turnover frequency(TOF)value of the Pd/TiO_(2) array was up to 8.00 min^(-1),which was approximately 4.2 times that of planar Pd/TiO_(2) film with the same area(1.91 min^(-1)).Our strategy of incorporating nanocatalysts with a hierarchical vertical array provides a promising approach to boosting the catalytic performance of catalysts for different chemical reactions.展开更多
In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion metho...In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion method,a green alternative to the traditional preparative routes.The catalyst was characterized using XRD,FTIR,SEM,EDX,XPS and TEM techniques.The synergistic effect of the composite CeO2/g-C3 N4/Ag was tested for catalytic reduction of 4-nitrophenol in the prese nce of sodium borohydride.The reaction was carried out at room tempe rature without any light source or exte rnal stirring.The individual and combined effects of four parameters,viz.,concentration of 4-NP,amount of catalyst,amount of NaBH4 and time for the reduction of reduction 4-NP were investigated using Box-Behnken design of response surface methodology(RSM).This statistical model was used to optimize the reaction conditions for maximum reduction of 4-NP.The optimum conditions for the reduction reaction are found to be 0.01 mmol/L 4-NP,15 mg catalyst,20 mg NaBH4 and 13.7 min time interval.展开更多
Here,Ag2S nanoparticles on reduced graphene oxide（Ag2S NPs/RGO） nanocomposites with relatively good distribution are synthesized for the first time by conversing Ag NPs/RGO to Ag2S NPs/RGO via a facile hydrothermal ...Here,Ag2S nanoparticles on reduced graphene oxide（Ag2S NPs/RGO） nanocomposites with relatively good distribution are synthesized for the first time by conversing Ag NPs/RGO to Ag2S NPs/RGO via a facile hydrothermal sulfurization method.As an noval catalyst for the reduction of 4-nitrophenol（4-NP）,it only takes 5 min for Ag2S NPs/RGO to reduce 98% of 4-NP,and the rate constant of the composites is almost 13 times higher than that of Ag NPs/RGO composites.The high catalytic activity of Ag2S NPs/RGO can be attributed to the following three reasons：（1） Like metal complex catalysts,the Ag2S NPs is also rich with metal center Ag（δ^＋）,with pendant base S（δ） close to it,and thus the Ag and basic S function as the electron-acceptor and proton-acceptor centers,respectively,which facilitates the catalyst reaction;（2）RGO features the high adsorption ability toward 4-NP which provides a high concentration of 4-NP near the Ag2S NPs;and（3） electron transfer from RGO to Ag2S NPs,facilitating the uptake of electrons by 4-NP molecules.展开更多
We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed ...We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed by an Ag17 core with C3 symmetry and the remaining 15 Ag atoms bond to each other and coordinate with the 24 surface ligands.When applied as electrocatalyst for CO_(2) reduction reaction(CO_(2)RR),Ag_(32) exhibited the highest Faradaic efficiency(FE)of CO up to 96.44%at−0.8 V with hydrogen evolution being significantly suppressed in a wide potential range,meanwhile it has a reaction rate constant of 0.242 min−1 at room temperature and an activation energy of 45.21 kJ·mol−1 in catalyzing the reduction of 4-nitrophenol,both markedly superior than the thiolate and phosphine ligand co-protected Ag_(32) nanocluster.Such strong ligand effect was further understood by density functional theory(DFT)calculations,as it revealed that,one single ligand stripping off from the intact cluster can create the undercoordinated Ag atom as the catalytically active site for both clusters,but alkynyl-protected Ag_(32) nanocluster possesses a smaller energy barrier for forming the key*COOH intermediate in CO_(2)RR,and favors the adsorption of 4-nitrophenol.This study not only discovers a new member of homoleptic alkynyl-protected Ag nanocluster,but also highlights the great potentials of employing alkynyl-protected Ag nanoclusters as bifunctional catalysts toward various reactions.展开更多
Titanium dioxide （TiO2） nanoparticles were prepared by sol gel route. The preparation parameters were optimized in the removal of 4-nitropbenol （4-NP）. All catalysts were analyzed by X-ray diffraction （XRD） and ...Titanium dioxide （TiO2） nanoparticles were prepared by sol gel route. The preparation parameters were optimized in the removal of 4-nitropbenol （4-NP）. All catalysts were analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. An artificial neural network model （ANN） was developed to predict the photocatalytic removal of 4-NP in the presence of TiOz nanoparticles prepared under desired conditions. The comparison between the predicted results by designed ANN model and the experimental data proved that modeling of the removal process of 4-NP using artificial neural network was a precise method to predict the extent of 4-NP removal under different conditions.展开更多
A novel technique of immobilizing indicator dyes by electrostatic adsorption and covalent bonding to fabricate optical sensors was developed.3-Amino-9-ethylcarbazole(AEC)was attached to the outmost surface of quartz g...A novel technique of immobilizing indicator dyes by electrostatic adsorption and covalent bonding to fabricate optical sensors was developed.3-Amino-9-ethylcarbazole(AEC)was attached to the outmost surface of quartz glass slide via aminosilanizing the slide,crosslinking chitosan,adsorbing Au nanoparticle,self-assembling HS(CH2)11OH,and coupling AEC.Thus, an AEC-immobilized optical sensor was obtained.The sensor exhibits a wide linear response range from 7.0×10- 7to 1.0×10 -4 mol/L and a correlation coefficient of 0.995 9 for the detection of 2-nitrophenol.The detection limit and response time of the sensor are 1.0×10- 7mol/L and less than 10 s,respectively.The fluorescence intensity of the used sensor can be restored to the blank value by simply rinsing with blank buffer.A very effective matrix for immobilizing indicator dye is provided by the proposed technique, which is adaptable to other indicator dyes with amino groups besides AEC.展开更多
文摘制备了不同阳离子掺杂改性的针铁矿,并采用XRD、红外、热重差热分析以及TEM等手段对其进行了表征,结果显示,掺入Mn^(2+)、Cr^(3+)、Al^(3+)后并未明显改变α-FeOOH的晶体结构类型,说明部分阳离子掺杂进入α-FeOOH晶格,从而分别形成因Fe^(3+)被Mn^(2+)、Cr^(3+)、Al^(3+)部分取代的固溶体;红外分析也得到类似结果;热重和差热分析以及TEM观察结果均表明几种金属阳离子没有形成氧化物相,可以确定这些离子已经进入针铁矿的晶格;紫外-可见漫反射光谱分析发现Mn^(2+)、Cr^(3+)掺杂者的能带隙较之纯相针铁矿的稍小,依次为2.18 e V和2.24 e V;而Al^(3+)掺杂者的能带隙与纯相针铁矿相比有所提高,增加至2.34 e V。此外还考查了不同阳离子掺杂及纯相针铁矿与Fe(Ⅱ)构成的复合系统对邻硝基苯酚(2-NP)的还原效果,研究表明,在溶液pH=6和25℃等的条件下,上述还原转化反应符合准一级动力学方程。其中,Fe(Ⅱ)/Al^(3+)掺杂针铁矿复合系统对2-NP的降解效果最好,在120 min时就达到了100%去除率,在一定浓度范围内,随着2-NP浓度的升高,2-NP的还原速率降低。而且,Fe(Ⅱ)/Al^(3+)-针铁矿复合系统速率常数(k)随着溶液的pH值增大而升高。
基金the financial supports from the National Natural Science Foundation of China (Nos. 51974116, 51874128)the Science Foundation of Hunan Province, China (Nos. 2020JJ4273, 2020JJ5130)。
文摘Palladium-supported cobalt hydroxide(Co(OH)_(2)-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol.For the preparation of Co(OH)2-Pd,Pd nanoparticles were anchored on the Co(OH)_(2) nanoplates after the reduction of Na;PdCl;by ascorbic acid in the absence of a stabilizer at room temperature.The observations under transmission and scanning electron microscopy reveal that Pd nanoparticles with a size of 2-5 nm are uniformly dispersed on the surface of the Co(OH)_(2) nanoplates.In catalytic test,the conversion of 4-nitrophenol to 4-aminophenol is completed within 6 min in the presence of Co(OH)_(2)-Pd(1000) nanoplates with2.18 at.% Pd,and the corresponding kinetic constant is 0.0089 s;in the first test.The catalyst retains relatively high activity after several cycles.The results demonstrate that the Co(OH)_(2)-Pd(1000) nanoplates exhibit high catalytic activity toward the reduction of 4-nitrophenol in the presence of NaBH;.
基金Supported by the Natural Science Foundation of Fujian Province(No.2017J01420)Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry(FJKL_FBCM201803)
文摘Cu2O@Cu nanocomposite was prepared by a simple high temperature calcination reaction in N2 atmosphere.The as-prepared samples were characterized by XRD,SEM and TEM,which indicated that the product formed by nano-sheets stacking had a high specific surface area.The as-synthesized material shows efficient catalytic activity for the reduction of organic compound in aqueous medium,in which 4-nitrophenol can be reduced to p-aminophenol and Congo red can be degraded to colorless solution.
基金supported by the State Key Laboratory of Organic-Inorganic Composites (No.oic-202101009)State Key Laboratory of Chemical Engineering (No.SKL-ChE-21A02),China。
文摘Toward the imperative treatment of the industrial wastewater containing 4-nitrophenol(4-NP)and industrial solid waste red mud(RM),an innovative approach of“Using waste to treat waste”is developed.Valuable element Al is leached from the RM first,the resultant NaAlO_(2) solution is hydrothermally converted toγ-AlOOH hierarchical porous microspheres(RMγ-AlOOH HPMSs,average diameter:2.0μm,SBET:77.81 m^(2) g^(-1),pore volume:0.38 cm^(3) g^(-1))in the presence of urea.The subsequent mild thermal conversion results inγ-Al_(2)O_(3) hierarchical porous microspheres(RMγ-Al_(2)O_(3) HPMSs).Both of the RMγ-AlOOH and RMγ-Al_(2)O_(3) HPMSs are employed as the Pd catalyst support for the catalytic reduction of 4-NP.Particularly,the as-obtained composite Pd/RMγ-AlOOH and Pd/RMγ-Al_(2)O_(3) exhibit excellent catalytic activities with superior knor as 8204.5 and 4831.4 s^(-1) g^(-1),respectively,significantly higher than that of most Pd based catalysts.Moreover,the excellent catalytic stability and durability of the Pd/RMγ-AlOOH and Pd/RMγ-Al_(2)O_(3) within 10 successive cycles of reduction enable the present industrial solid waste RM inducedγ-AlOOH andγ-Al_(2)O_(3) HPMSs as great promising Pd catalyst support for the reduction of the industrial wastewater containing 4-NP.
文摘The development of effective catalysts for the catalytic conversion of the harmful nitrophenol （NP） into the useful aminophenol （AP） has received extensive interest. Herein, we report the easy and large-scale synthesis of strongly coupled Ag/TiO2 heterojunctions based on the coordinated action of organic components with a multi-kind metal precursor. The heterojunctions were effective and stable catalysts for the photothermal catalytic reduction of 4-NP to 4-AP. In the synthesis, critic acid, ethylene glycol AgNO3, and tetrabutyl titanate were dissolved and coordinated in water. Under heating, a precursor gel having a uniform distribution of Ag and Ti was gradually formed. Via calcination in air, the Ti precursor was transformed into TiO2, accompanied by the reduction of Ag＋ to Ag nanoparticles. The formation of Ag/TiO2 composites with intimate interface contact benefited from the uniform distribution of different components in the precursor gel. The Ag/TiO2 functioned as an effective catalyst for the reduction of 4-NP, exhibiting higher activity than the many reported Ag-based catalysts. The catalytic reaction over Ag/TiO2 had a small to with good activity and reuse performance. After 10 cycles of reuse, the conversion efficiency exhibited no obvious change. Importantly, the conversion of 4-NP was significantly enhanced under light irradiation provided by a 150-W Xe lamp （the visible light from cutoff have equal function）, but ultraviolet light did not promote the conversion. The conversion time was reduced from 620 to 270 s with light irradiation （15 ~C）. The reaction rate under light irradiation （0.014 s-1） was approximately three times higher than that in the dark at 15 ~C （0.0044 s-1） and even better than that in the dark at 25 ~C （0.01 s-l）. A series of experiments indicated that the light irradiation promoted the conversion of 4-NP because of the localized surface plasmon resonance effect of Ag, which generated hot e- and h~ particles and local heating around the particles via their absorption of the light.
基金supported by the National Natural Science Foundation of China(Nos.22072104 and 21822202)the“Nano Frontier”Key Special Project of the National Key R&D Program of China(Nos.2022YFA1200129,2022YFA1205303 and 2022YFA1205300)+1 种基金the Project of the Suzhou Key Laboratory of Surface and Interface of Intelligent Matter,China(No.SZS_(2)022011)the Project Funded by CIC and the 111 Project.
文摘Catalytic degradation of organic contaminants is at the frontier of water treatment due to its selectivity,energy savings,and ability to convert harmful contaminants into harmless or even valuable chemical products for recycling.However,achieving sufficiently high performance in the catalytic removal of organic contaminants for practical application is still extremely challenging.Herein,we report a Pd-decorated TiO_(2)(Pd/TiO_(2))hierarchical vertical array for fast and efficient catalytic water treatment.Such a forest-like Pd/TiO_(2) vertical array demonstrates the following distinct advantages over conventional planar or bulk catalytic systems:1)abundant anchoring sites for nanocrystals loading;2)high sunlight absorption;3)efficient mass transfer channels for the reactants and products.As a proof of concept,the Pd/TiO_(2) array demonstrated rapid and efficient photo-assisted catalytic reduction of high concentrations of 4-nitrophenol wastewater(2 g/L,ca.14.38 mmol/L)and its feasibility for continuous flow wastewater treatment.The turnover frequency(TOF)value of the Pd/TiO_(2) array was up to 8.00 min^(-1),which was approximately 4.2 times that of planar Pd/TiO_(2) film with the same area(1.91 min^(-1)).Our strategy of incorporating nanocatalysts with a hierarchical vertical array provides a promising approach to boosting the catalytic performance of catalysts for different chemical reactions.
文摘In this study,the enhancement of catalytic activity of ceria when modified with co-catalysts such as graphitic carbon nitride and silver was establishe d.The material was synthe sized using phytogenic combustion method,a green alternative to the traditional preparative routes.The catalyst was characterized using XRD,FTIR,SEM,EDX,XPS and TEM techniques.The synergistic effect of the composite CeO2/g-C3 N4/Ag was tested for catalytic reduction of 4-nitrophenol in the prese nce of sodium borohydride.The reaction was carried out at room tempe rature without any light source or exte rnal stirring.The individual and combined effects of four parameters,viz.,concentration of 4-NP,amount of catalyst,amount of NaBH4 and time for the reduction of reduction 4-NP were investigated using Box-Behnken design of response surface methodology(RSM).This statistical model was used to optimize the reaction conditions for maximum reduction of 4-NP.The optimum conditions for the reduction reaction are found to be 0.01 mmol/L 4-NP,15 mg catalyst,20 mg NaBH4 and 13.7 min time interval.
文摘Here,Ag2S nanoparticles on reduced graphene oxide（Ag2S NPs/RGO） nanocomposites with relatively good distribution are synthesized for the first time by conversing Ag NPs/RGO to Ag2S NPs/RGO via a facile hydrothermal sulfurization method.As an noval catalyst for the reduction of 4-nitrophenol（4-NP）,it only takes 5 min for Ag2S NPs/RGO to reduce 98% of 4-NP,and the rate constant of the composites is almost 13 times higher than that of Ag NPs/RGO composites.The high catalytic activity of Ag2S NPs/RGO can be attributed to the following three reasons：（1） Like metal complex catalysts,the Ag2S NPs is also rich with metal center Ag（δ^＋）,with pendant base S（δ） close to it,and thus the Ag and basic S function as the electron-acceptor and proton-acceptor centers,respectively,which facilitates the catalyst reaction;（2）RGO features the high adsorption ability toward 4-NP which provides a high concentration of 4-NP near the Ag2S NPs;and（3） electron transfer from RGO to Ag2S NPs,facilitating the uptake of electrons by 4-NP molecules.
基金supported by the Open Fund of Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications(No.2021A07)support from Guangdong Natural Science Funds(No.2022A1515011840)+2 种基金the National Natural Science Foundation of China(No.21805170)the National Natural Science Foundation of China(No.21903008)the Chongqing Science and Technology Commission(No.cstc2020jcyj-msxmX0382).
文摘We report a superatomic homoleptic alkynyl-protected Ag_(32)L_(24)(L=3,5-bis(trifluoromethylbenzene)acetylide,Ag_(32) for short)nanocluster with atomic precision,which possesses eight free electrons.Ag_(32) is formed by an Ag17 core with C3 symmetry and the remaining 15 Ag atoms bond to each other and coordinate with the 24 surface ligands.When applied as electrocatalyst for CO_(2) reduction reaction(CO_(2)RR),Ag_(32) exhibited the highest Faradaic efficiency(FE)of CO up to 96.44%at−0.8 V with hydrogen evolution being significantly suppressed in a wide potential range,meanwhile it has a reaction rate constant of 0.242 min−1 at room temperature and an activation energy of 45.21 kJ·mol−1 in catalyzing the reduction of 4-nitrophenol,both markedly superior than the thiolate and phosphine ligand co-protected Ag_(32) nanocluster.Such strong ligand effect was further understood by density functional theory(DFT)calculations,as it revealed that,one single ligand stripping off from the intact cluster can create the undercoordinated Ag atom as the catalytically active site for both clusters,but alkynyl-protected Ag_(32) nanocluster possesses a smaller energy barrier for forming the key*COOH intermediate in CO_(2)RR,and favors the adsorption of 4-nitrophenol.This study not only discovers a new member of homoleptic alkynyl-protected Ag nanocluster,but also highlights the great potentials of employing alkynyl-protected Ag nanoclusters as bifunctional catalysts toward various reactions.
文摘Titanium dioxide （TiO2） nanoparticles were prepared by sol gel route. The preparation parameters were optimized in the removal of 4-nitropbenol （4-NP）. All catalysts were analyzed by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. An artificial neural network model （ANN） was developed to predict the photocatalytic removal of 4-NP in the presence of TiOz nanoparticles prepared under desired conditions. The comparison between the predicted results by designed ANN model and the experimental data proved that modeling of the removal process of 4-NP using artificial neural network was a precise method to predict the extent of 4-NP removal under different conditions.
基金Project(20775010)supported by the National Natural Science Foundation of ChinaProject(208095)supported by the Key Project ofMinistry of Education,China+1 种基金Project(07A006)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(07JJ3020)supported by Hunan Provincial Natural Science Foundation of China
文摘A novel technique of immobilizing indicator dyes by electrostatic adsorption and covalent bonding to fabricate optical sensors was developed.3-Amino-9-ethylcarbazole(AEC)was attached to the outmost surface of quartz glass slide via aminosilanizing the slide,crosslinking chitosan,adsorbing Au nanoparticle,self-assembling HS(CH2)11OH,and coupling AEC.Thus, an AEC-immobilized optical sensor was obtained.The sensor exhibits a wide linear response range from 7.0×10- 7to 1.0×10 -4 mol/L and a correlation coefficient of 0.995 9 for the detection of 2-nitrophenol.The detection limit and response time of the sensor are 1.0×10- 7mol/L and less than 10 s,respectively.The fluorescence intensity of the used sensor can be restored to the blank value by simply rinsing with blank buffer.A very effective matrix for immobilizing indicator dye is provided by the proposed technique, which is adaptable to other indicator dyes with amino groups besides AEC.
