The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Shifu Chen - One of the best experts on this subject based on the ideXlab platform.
-
Simultaneous dehydrogenation and hydrogenolysis of Aromatic Alcohols in one reaction system via visible-light-driven heterogeneous photocatalysis
Journal of Catalysis, 2020Co-Authors: Sugang Meng, Xianliang Fu, Xiangju Ye, Xiaofeng Ning, Susheng Chang, Shifu ChenAbstract:Abstract Photocatalytic selective organic transformation using photoexcited holes and electrons has attracted worldwide interest. Although extensive studies have made significant progress in dehydrogenation of Alcohols, hydrogenolysis of Alcohols using photoexcited electrons directly constitutes a challenge. Here, photocatalytic selective dehydrogenation and hydrogenolysis of Aromatic Alcohols into corresponding alkanes/ethers and aldehydes has been achieved by direct use of photoexcited electrons and holes over CdS under visible light irradiation. Compared with other popular visible-light-driven photocatalysts, Sb 2 S 3 , Bi 2 O 3 , N-doped TiO 2 , Zn 3 In 2 S 6 , g-C 3 N 4 , and Ce 2 S 3 , the sum of the yields of alkanes and aldehydes over the as-prepared CdS could reach up to 94% after reaction for 4 h. The high photoactivity and stability of CdS toward dehydrogenation and hydrogenolysis of Aromatic Alcohols can be ascribed to its appropriate band potentials and effective charge separation–transportation. The optimum positions are that the valence band position should be located between oxidation potentials of alcohol/aldehyde and aldehyde/oxidized aldehyde, and the conduction band position should be more slightly negative than reduction potential of alkane/alcohol. During this reaction, the dehydrogenation reaction consumes two holes and produces two protons; the hydrogenolysis process depletes two electrons and two protons. Therefore, a cooperative, cyclical, and efficient reaction system was established.
-
Self-Assembly of CdS/CdIn2S4 Heterostructure with Enhanced Photocascade Synthesis of Schiff Base Compounds in an Aromatic Alcohols and Nitrobenzene System with Visible Light.
ACS Applied Materials & Interfaces, 2019Co-Authors: Qiaoqiao Zhang, Xiangju Ye, Jinxin Wang, Longqiang Ye, Xuchun Wang, Shifu ChenAbstract:A series of novel CdS/CdIn2S4 composite materials were prepared via a one-pot solvothermal process. The as-obtained photocatalysts were characterized by several techniques and the photocatalytic properties of CdS/CdIn2S4 photocatalysts were studied by photocascade synthesis of Schiff base compounds in a photocatalytic reaction system of Aromatic Alcohols and nitrobenzene irradiated with visible light. The results reveal that the resulting CdS/CdIn2S4 heterostructure samples show outstanding photocatalytic activities toward the photocascade production of Schiff base compounds in an Aromatic Alcohols and nitrobenzene reaction system irradiated with visible light. An optimized 50.0% CdS/CdIn2S4 heterostructure sample shows the highest Schiff base yield of 42.0% irradiated with visible light for 4 h, which is approximately 19.1 and 1.54 times higher than those of sole CdS and CdIn2S4 samples, respectively. The fabrication of heterogeneous structure improves the spatial separation and migration of photoinduced...
-
Effective use of photogenerated electrons and holes in a system: Photocatalytic selective oxidation of Aromatic Alcohols to aldehydes and hydrogen production
Journal of Catalysis, 2018Co-Authors: Sugang Meng, Xianliang Fu, Jinghu Zhang, Xiangju Ye, Shifu ChenAbstract:Abstract Effective utilization of photogenerated electrons and holes in a system is always a research hotspot. Photocatalysis has been identified as a promising solution to tackle the current environmental and energy issues. However, photogenerated holes or electrons were wasted in the traditional photocatalytic process. In the paper, a dual-function photocatalytic reaction system was constructed using dispersed Ptx-modified 2D-3D Zn3In2S6 hierarchical structures (x = 1–4). In the system, Aromatic Alcohols were photocatalytically selectively oxidated into aldehydes and protons were reduced to hydrogen by photogenerated holes and electrons, respectively. In the reaction process, one Aromatic alcohol is first dehydrogenated into Aromatic aldehyde and two H+ via the corresponding carbon-centered radical by consuming of two holes, and then two H+ ions dehydrogenated from OH group and α C H of alcohol are evolved into H2 by depleting of two electrons. Atomically dispersed Ptx could offer the maximum atom efficiency and significantly promote visible light absorption and separation of photogenerated electron-hole pairs. The cooperative photoredox system exhibits remarkable photocatalytic activity for visible light-driven splitting of Aromatic Alcohols. Under visible light irradiation for 6 h, The H2 output over 2.14% Pt/Zn3In2S6 reaches up to 950 μmol, which is around 7.5, 5.3 and 3.8 times higher than that over Zn3In2S6, Pt-nanoparticle/Zn3In2S6 and MoS2/Zn3In2S6, respectively. The apparent quantum efficiency (AQE) of 2.14% Pt/Zn3In2S6 at 400 nm is about 4.6%. The utilization rate of photogenerated electrons to holes could be achieved 98.2%. Moreover, Pt/Zn3In2S6 hybrid shows high stability even when Zn3In2S6 was stored for 12 months. Compared with two half-reactions: the photocatalytic selective organics transformation under O2 atmosphere and the water splitting with sacrificial reagents, such designed dual-purpose photocatalytic reaction not only could effective use of photogenerated electrons and holes for organics transformation and hydrogen production simultaneously but also shows much higher photocatalytic activity than two half-reactions. At the same time, the work also expands the research field of photocatalysis, such as N2 fixation and CO2 reduction by using of the as-produced H+.
-
Photocatalytic organic transformations: Simultaneous oxidation of Aromatic Alcohols and reduction of nitroarenes on CdLa2S4 in one reaction system
Applied Catalysis B-environmental, 2018Co-Authors: Sujuan Zhang, Sugang Meng, Xianliang Fu, Xiangju Ye, Weixin Huang, Xiuzhen Zheng, Shifu ChenAbstract:Abstract Photocatalytic selective organic transformations (SOTs) with sunlight offer a “green” route for synthesis of fine chemicals. In this work, a bare ternary chalcogenide CdLa2S4 photocatalyst was fabricated to couple the selective oxidation (SO) of Aromatic Alcohols to aldehydes and selective reduction (SR) of nitroarenes to anilines in one reaction system. The photocatalyst showed a high stability and a good generality for the conversions due to the well–matched band structure and the high separation efficiency of photoinduced electrons (e–) and holes (h+). For p–substituted Aromatic Alcohols, the selectivities to the corresponding aldehydes are as high as ca. 90%. The electro–donating substituent in the para position benefits the SO reactions, which are triggered by h+ via a successive deprotonation; while for p–substituted nitroarenes, the SR to the corresponding anilines is vulnerable to the electro–withdrawing groups and the steric hindrance of the substituent and the selectivities to anilines are substantially lower than that of the SO conversions. H+ deprotonated in the SO of Aromatic Alcohols is indispensable for the SR of nitroarenes as they are achieved by a H+–coupled six e– reduction process, which leads to the low conversion efficiencies. The half conversions not only be coupled by the photoinduced e– and h+, but also collaborate with each other through H+. Our results clearly demonstrate the emerging concept of a coupled reaction system for sunlight–driven synthesis of fine chemicals and reveal the underlying mechanism.
-
Ultra-low content of Pt modified CdS nanorods: Preparation, characterization, and application for photocatalytic selective oxidation of Aromatic Alcohols and reduction of nitroarenes in one reaction system
Journal of Hazardous Materials, 2018Co-Authors: Sujuan Zhang, Sugang Meng, Xianliang Fu, Weixin Huang, Gaoli Chen, Shifu ChenAbstract:Abstract A series of Pt nanoparticles (with size of 3–4 nm) decorated CdS nanorods were prepared via a simple solvothermal method. The samples were then used for photocatalytic selective oxidation (SO) of Aromatic Alcohols and reduction (SR) of nitroarenes in one reaction system. The platinized samples showed enhanced activity for the conversions than pristine CdS as Pt can serve as e− trapping and reaction sites, by which the recombination of photoinduced charge carriers can be suppressed and the adsorption of reactants and the SR of nitroarenes can be promoted. The sample loaded with only of 0.03% Pt showed the highest performance and, after irradiation for 4 h, the conversions of p-methoxybenzyl alcohol and nitrobenzene are as high as 92.7% and 94.8%, while the yields of p-methoxybenzaldehyde and aniline are 80.5% and 36.0%. The activities are about 2.0 times higher than that of CdS. The coupling reaction mechanism for the SO of Aromatic Alcohols to aldehydes and SR of nitroarenes to anilines in the reaction system was finally proposed.
Zhaohui Li - One of the best experts on this subject based on the ideXlab platform.
-
Bi-functional NH2-MIL-101(Fe) for one-pot tandem photo-oxidation/Knoevenagel condensation between Aromatic Alcohols and active methylene compounds
Catalysis Science & Technology, 2020Co-Authors: Dengke Wang, Zhaohui LiAbstract:Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH2-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between Aromatic Alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH2-MIL-101(Fe) acts as a photocatalyst for the oxidation of Aromatic Alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH2-MIL-101(Fe) and another two MOFs (NH2-UiO-66(Zr) and NH2-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.
-
bi functional nh2 mil 101 fe for one pot tandem photo oxidation knoevenagel condensation between Aromatic Alcohols and active methylene compounds
Catalysis Science & Technology, 2015Co-Authors: Dengke Wang, Zhaohui LiAbstract:Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH2-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between Aromatic Alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH2-MIL-101(Fe) acts as a photocatalyst for the oxidation of Aromatic Alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH2-MIL-101(Fe) and another two MOFs (NH2-UiO-66(Zr) and NH2-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.
Sedat Yurdakal - One of the best experts on this subject based on the ideXlab platform.
-
Photocatalytic oxidation of Aromatic Alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide
Applied Catalysis A: General, 2020Co-Authors: Vincenzo Augugliaro, Giovanni Palmisano, Vittorio Loddo, Leonardo Palmisano, Horst Kisch, María José López-muñoz, Carlos Márquez-Álvarez, Francesco Parrino, Sedat YurdakalAbstract:Oxygenated aqueous suspensions of home-prepared (HP) and commercial TiO2 catalysts were used in a batch photoreactor for carrying out the oxidation of benzyl alcohol (BA) and 4-methoxybenzyl alcohol (MBA) under different operative conditions. HP catalysts were synthesized from TiCl4 and underwent a hydrolysis treatment of different times under mild conditions. The textural characterisation of catalysts was carried out with XRD, SEM observations, BET surface area and porosity measurements. For both Alcohols the main oxidation products were the corresponding Aromatic aldehydes and CO2. The HP catalysts exhibited selectivity values towards the aldehyde production up to 28% (BA conversion: 50%) and 41% (MBA conversion: 65%), about four times higher than those of commercial TiO2. The addition of an aliphatic alcohol (methanol, ethanol, 2-propanol or tert-butanol) in small amounts with respect to water decreased the overall oxidation rate of Aromatic Alcohols but enhanced the selectivity for aldehyde formation up to 1.5 times. The reactivity results suggest that: (i) the Aromatic alcohol molecules interact with the TiO2 surface in different ways that eventually determine two parallel reaction pathways (partial oxidation or mineralization); and (ii) the aliphatic Alcohols preferentially compete with Aromatic Alcohols for the mineralizing pathway
-
Partial oxidation of Aromatic Alcohols via TiO2 photocatalysis: the influence of substituent groups on the activity and selectivity
RSC Advances, 2012Co-Authors: Sedat Yurdakal, Vincenzo AugugliaroAbstract:Aromatic Alcohols with substituent groups in different positions have been partially oxidised to the corresponding aldehydes in a photocatalytic system in order to investigate the influence of the substituents on reactivity and selectivity to aldehyde. To this aim benzyl alcohol, 2-methoxybenzyl alcohol, 3-methoxybenzyl alcohol, 4-methoxybenzyl alcohol, 2,4-dimethoxybenzyl alcohol, 4-hydroxybenzyl alcohol and 4-hydroxy-3-methoxybenzyl alcohol have been photocatalytically oxidised to their corresponding aldehydes in aqueous TiO2 suspensions under near-UV irradiation. Home-made and commercial rutile TiO2 samples were used as photocatalysts. The catalysts were characterized by XRD, BET, SEM, TEM and TGA measurements. For all the used substrates the main oxidation products were the corresponding aldehydes and CO2. The Aromatic Alcohols showed selectivity values decreasing with the substituent position on the Aromatic ring according the following order: para > ortho > meta. In the presence of two substituent groups, the overall oxidation rate increased while the selectivity decreased. The home-made catalyst generally showed selectivity higher but activity lower than those of the commercial one. The results showed that the reaction rate and selectivity were dependent not only on the catalyst properties such as crystallinity and hydrophilicity but also on the kind and position of the substituent groups of the Aromatic Alcohols.
-
selective photocatalytic oxidation of 4 substituted Aromatic Alcohols in water with rutile tio2 prepared at room temperature
Green Chemistry, 2009Co-Authors: Sedat Yurdakal, Giovanni Palmisano, Vittorio Loddo, Vincenzo Augugliaro, Oguzhan Alagoz, Leonardo PalmisanoAbstract:Home-prepared (HP) rutile TiO2catalysts were prepared at room temperature by using H2O and TiCl4 in different ratios and without addition of additives. The catalysts were used for carrying out the selective photocatalytic oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde in aqueous suspension, free from any organic co-solvent. The selectivities showed by the home prepared catalysts were in the 45–74% range, up to four times higher than that of a commercial rutile TiO2 sample, the reaction rates being comparable. By using the most selective photocatalyst, the oxidation of benzyl, 4-methylbenzyl, and 4-nitrobenzyl Alcohols was also carried out in order to investigate the influence of the substituent group on the oxidation rate and selectivity. The presence of an –OCH3group positively influenced the selectivity whereas a –NO2group showed to have a detrimental effect. The Hammett relationship effectively describes the influence of substituent group on the kinetic constant of partial oxidation of Aromatic Alcohols to aldehydes.
-
Photocatalytic oxidation of Aromatic Alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide: 1. Selectivity enhancement by aliphatic Alcohols
Applied Catalysis A-general, 2008Co-Authors: Vincenzo Augugliaro, Giovanni Palmisano, Vittorio Loddo, Leonardo Palmisano, Horst Kisch, María José López-muñoz, Carlos Márquez-Álvarez, Francesco Parrino, Sedat YurdakalAbstract:Abstract Oxygenated aqueous suspensions of home-prepared (HP) and commercial TiO2 catalysts were used in a batch photoreactor for carrying out the oxidation of benzyl alcohol (BA) and 4-methoxybenzyl alcohol (MBA) under different operative conditions. HP catalysts were synthesized from TiCl4 and underwent a hydrolysis treatment of different times under mild conditions. The textural characterization of catalysts was carried out with XRD, SEM observations, BET surface area and porosity measurements. For both Alcohols the main oxidation products were the corresponding Aromatic aldehydes and CO2. The HP catalysts exhibited selectivity values towards the aldehyde production up to 28% (BA conversion: 50%) and 41% (MBA conversion: 65%), about four times higher than those of commercial TiO2. The addition of an aliphatic alcohol (methanol, ethanol, 2-propanol or tert-butanol) in small amounts with respect to water decreased the overall oxidation rate of Aromatic Alcohols but enhanced the selectivity for aldehyde formation up to 1.5 times. The reactivity results suggest that: (i) the Aromatic alcohol molecules interact with the TiO2 surface in different ways that eventually determine two parallel reaction pathways (partial oxidation or mineralization); (ii) the aliphatic Alcohols preferentially compete with Aromatic Alcohols for the mineralizing pathway.
-
nanostructured rutile tio2 for selective photocatalytic oxidation of Aromatic Alcohols to aldehydes in water
Journal of the American Chemical Society, 2008Co-Authors: Sedat Yurdakal, Giovanni Palmisano, Vittorio Loddo, Vincenzo Augugliaro, Leonardo PalmisanoAbstract:Selective photocatalytic oxidation of Aromatic Alcohols to aldehydes was performed in water in the presence of TiO2 rutile photocatalysts that exhibited a low degree of crystallinity. The nanostructured rutile samples, prepared ex TiCl4 at very low temperature, ensured a selectivity toward the aldehyde 3 to 4-fold higher than the commercial rutile tested (Sigma-Aldrich).
Dengke Wang - One of the best experts on this subject based on the ideXlab platform.
-
Bi-functional NH2-MIL-101(Fe) for one-pot tandem photo-oxidation/Knoevenagel condensation between Aromatic Alcohols and active methylene compounds
Catalysis Science & Technology, 2020Co-Authors: Dengke Wang, Zhaohui LiAbstract:Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH2-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between Aromatic Alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH2-MIL-101(Fe) acts as a photocatalyst for the oxidation of Aromatic Alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH2-MIL-101(Fe) and another two MOFs (NH2-UiO-66(Zr) and NH2-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.
-
bi functional nh2 mil 101 fe for one pot tandem photo oxidation knoevenagel condensation between Aromatic Alcohols and active methylene compounds
Catalysis Science & Technology, 2015Co-Authors: Dengke Wang, Zhaohui LiAbstract:Tandem reactions, which enable multistep reactions in one pot, offer enormous economical advantages. For the first time, this manuscript reported that NH2-MIL-101(Fe), an earth abundant Fe-containing MOF material, can catalyze efficiently the one-pot reaction between Aromatic Alcohols and active methylene compounds via a tandem photo-oxidation/Knoevenagel condensation under visible light and at room temperature. NH2-MIL-101(Fe) acts as a photocatalyst for the oxidation of Aromatic Alcohols to aldehydes as well as a base catalyst for Knoevenagel condensation between the as-formed aldehydes and the active methylene compounds. The comparison of the reactions over NH2-MIL-101(Fe) and another two MOFs (NH2-UiO-66(Zr) and NH2-MIL-125(Ti)) reveals that the strength of the basic sites in the MOFs influences significantly the efficiency of the tandem reaction. This study highlights the great potential of MOFs as multifunctional photocatalysts for one-pot tandem reactions.
Sugang Meng - One of the best experts on this subject based on the ideXlab platform.
-
Simultaneous dehydrogenation and hydrogenolysis of Aromatic Alcohols in one reaction system via visible-light-driven heterogeneous photocatalysis
Journal of Catalysis, 2020Co-Authors: Sugang Meng, Xianliang Fu, Xiangju Ye, Xiaofeng Ning, Susheng Chang, Shifu ChenAbstract:Abstract Photocatalytic selective organic transformation using photoexcited holes and electrons has attracted worldwide interest. Although extensive studies have made significant progress in dehydrogenation of Alcohols, hydrogenolysis of Alcohols using photoexcited electrons directly constitutes a challenge. Here, photocatalytic selective dehydrogenation and hydrogenolysis of Aromatic Alcohols into corresponding alkanes/ethers and aldehydes has been achieved by direct use of photoexcited electrons and holes over CdS under visible light irradiation. Compared with other popular visible-light-driven photocatalysts, Sb 2 S 3 , Bi 2 O 3 , N-doped TiO 2 , Zn 3 In 2 S 6 , g-C 3 N 4 , and Ce 2 S 3 , the sum of the yields of alkanes and aldehydes over the as-prepared CdS could reach up to 94% after reaction for 4 h. The high photoactivity and stability of CdS toward dehydrogenation and hydrogenolysis of Aromatic Alcohols can be ascribed to its appropriate band potentials and effective charge separation–transportation. The optimum positions are that the valence band position should be located between oxidation potentials of alcohol/aldehyde and aldehyde/oxidized aldehyde, and the conduction band position should be more slightly negative than reduction potential of alkane/alcohol. During this reaction, the dehydrogenation reaction consumes two holes and produces two protons; the hydrogenolysis process depletes two electrons and two protons. Therefore, a cooperative, cyclical, and efficient reaction system was established.
-
Effective use of photogenerated electrons and holes in a system: Photocatalytic selective oxidation of Aromatic Alcohols to aldehydes and hydrogen production
Journal of Catalysis, 2018Co-Authors: Sugang Meng, Xianliang Fu, Jinghu Zhang, Xiangju Ye, Shifu ChenAbstract:Abstract Effective utilization of photogenerated electrons and holes in a system is always a research hotspot. Photocatalysis has been identified as a promising solution to tackle the current environmental and energy issues. However, photogenerated holes or electrons were wasted in the traditional photocatalytic process. In the paper, a dual-function photocatalytic reaction system was constructed using dispersed Ptx-modified 2D-3D Zn3In2S6 hierarchical structures (x = 1–4). In the system, Aromatic Alcohols were photocatalytically selectively oxidated into aldehydes and protons were reduced to hydrogen by photogenerated holes and electrons, respectively. In the reaction process, one Aromatic alcohol is first dehydrogenated into Aromatic aldehyde and two H+ via the corresponding carbon-centered radical by consuming of two holes, and then two H+ ions dehydrogenated from OH group and α C H of alcohol are evolved into H2 by depleting of two electrons. Atomically dispersed Ptx could offer the maximum atom efficiency and significantly promote visible light absorption and separation of photogenerated electron-hole pairs. The cooperative photoredox system exhibits remarkable photocatalytic activity for visible light-driven splitting of Aromatic Alcohols. Under visible light irradiation for 6 h, The H2 output over 2.14% Pt/Zn3In2S6 reaches up to 950 μmol, which is around 7.5, 5.3 and 3.8 times higher than that over Zn3In2S6, Pt-nanoparticle/Zn3In2S6 and MoS2/Zn3In2S6, respectively. The apparent quantum efficiency (AQE) of 2.14% Pt/Zn3In2S6 at 400 nm is about 4.6%. The utilization rate of photogenerated electrons to holes could be achieved 98.2%. Moreover, Pt/Zn3In2S6 hybrid shows high stability even when Zn3In2S6 was stored for 12 months. Compared with two half-reactions: the photocatalytic selective organics transformation under O2 atmosphere and the water splitting with sacrificial reagents, such designed dual-purpose photocatalytic reaction not only could effective use of photogenerated electrons and holes for organics transformation and hydrogen production simultaneously but also shows much higher photocatalytic activity than two half-reactions. At the same time, the work also expands the research field of photocatalysis, such as N2 fixation and CO2 reduction by using of the as-produced H+.
-
Photocatalytic organic transformations: Simultaneous oxidation of Aromatic Alcohols and reduction of nitroarenes on CdLa2S4 in one reaction system
Applied Catalysis B-environmental, 2018Co-Authors: Sujuan Zhang, Sugang Meng, Xianliang Fu, Xiangju Ye, Weixin Huang, Xiuzhen Zheng, Shifu ChenAbstract:Abstract Photocatalytic selective organic transformations (SOTs) with sunlight offer a “green” route for synthesis of fine chemicals. In this work, a bare ternary chalcogenide CdLa2S4 photocatalyst was fabricated to couple the selective oxidation (SO) of Aromatic Alcohols to aldehydes and selective reduction (SR) of nitroarenes to anilines in one reaction system. The photocatalyst showed a high stability and a good generality for the conversions due to the well–matched band structure and the high separation efficiency of photoinduced electrons (e–) and holes (h+). For p–substituted Aromatic Alcohols, the selectivities to the corresponding aldehydes are as high as ca. 90%. The electro–donating substituent in the para position benefits the SO reactions, which are triggered by h+ via a successive deprotonation; while for p–substituted nitroarenes, the SR to the corresponding anilines is vulnerable to the electro–withdrawing groups and the steric hindrance of the substituent and the selectivities to anilines are substantially lower than that of the SO conversions. H+ deprotonated in the SO of Aromatic Alcohols is indispensable for the SR of nitroarenes as they are achieved by a H+–coupled six e– reduction process, which leads to the low conversion efficiencies. The half conversions not only be coupled by the photoinduced e– and h+, but also collaborate with each other through H+. Our results clearly demonstrate the emerging concept of a coupled reaction system for sunlight–driven synthesis of fine chemicals and reveal the underlying mechanism.
-
Ultra-low content of Pt modified CdS nanorods: Preparation, characterization, and application for photocatalytic selective oxidation of Aromatic Alcohols and reduction of nitroarenes in one reaction system
Journal of Hazardous Materials, 2018Co-Authors: Sujuan Zhang, Sugang Meng, Xianliang Fu, Weixin Huang, Gaoli Chen, Shifu ChenAbstract:Abstract A series of Pt nanoparticles (with size of 3–4 nm) decorated CdS nanorods were prepared via a simple solvothermal method. The samples were then used for photocatalytic selective oxidation (SO) of Aromatic Alcohols and reduction (SR) of nitroarenes in one reaction system. The platinized samples showed enhanced activity for the conversions than pristine CdS as Pt can serve as e− trapping and reaction sites, by which the recombination of photoinduced charge carriers can be suppressed and the adsorption of reactants and the SR of nitroarenes can be promoted. The sample loaded with only of 0.03% Pt showed the highest performance and, after irradiation for 4 h, the conversions of p-methoxybenzyl alcohol and nitrobenzene are as high as 92.7% and 94.8%, while the yields of p-methoxybenzaldehyde and aniline are 80.5% and 36.0%. The activities are about 2.0 times higher than that of CdS. The coupling reaction mechanism for the SO of Aromatic Alcohols to aldehydes and SR of nitroarenes to anilines in the reaction system was finally proposed.
-
Synergistic effect of photocatalysis and thermocatalysis for selective oxidation of Aromatic Alcohols to Aromatic aldehydes using Zn3In2S6@ZnO composite
Applied Catalysis B-environmental, 2017Co-Authors: Jinghu Zhang, Sugang Meng, Xianliang Fu, Xiangju Ye, Cancan Ling, Sujuan Zhang, Shifu ChenAbstract:Abstract Selective oxidation of Aromatic Alcohols to corresponding carbonyl compounds under mild conditions has a promising prospect in industry. In the paper, we successfully prepared a new mode of photothermocatalyst, Zn3In2S6@ZnO composite, which shows dramatically enhanced activity for selective oxidation of benzyl alcohol to benzaldehyde compared with single Zn3In2S6 and ZnO under visible light illumination. The enhancement is due to a synergistic effect of low-temperature thermocatalysis on ZnO and photocatalysis on Zn3In2S6. ZnO could weaken bonds of the C Hα and the O H. Then the reactive species ( O2− and h+) generated on Zn3In2S6 could be easy for selective oxidation of benzyl alcohol to produce benzaldehyde. The photoelectrochemical and photoluminescence (PL) results and a series of control experiments (e.g. reaction temperature and radical scavenger) prove this synergistic effect and proposed mechanism. Moreover, the stable performance and high activity of Zn3In2S6@ZnO for other Aromatic Alcohols indicate its applicable potential. This study provides a promising way to combine photocatalysis and thermocatalysis for the design of novel and efficient visible-light-driven catalyst for selective oxidation of Aromatic Alcohols or other organics under mild reaction conditions.
