氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过...氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过浸渍法制备了不同Ru负载量(质量分数分别为0.5%、1.0%和2.0%)的催化剂(分别为0.5%Ru/Si_(3)N_(4)、1.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)),并以商品氮化硅(Si_(3)N_(4)-C)为载体制备了2.0%Ru/Si_(3)N_(4)-C催化剂作为对照组。表征了催化剂的理化性质,测试了其在300℃、0.1 MPa下的CO_(2)加氢反应活性。结果显示,与Si_(3)N_(4)-C相比,Si_(3)N_(4)的比表面积较高(502 m^(2)/g),Si_(3)N_(4)作为载体显著提高了金属分散度,降低了金属粒径,催化剂暴露出更多的活性位点。0.5%Ru/Si_(3)N_(4)的金属粒径较小,展现出强的H_(2)吸附能力,H难以解吸,抑制了中间物种CO加氢生成CH_(4)。随着Ru负载量增加,金属粒径增大,催化剂的CH_(4)选择性更好。Ru/Si_(3)N_(4)系列催化剂中,2.0%Ru/Si_(3)N_(4)的CH_(4)选择性较高(98.8%)。空速为10000 m L/(g·h)时,0.5%Ru/Si_(3)N_(4)的CO选择性为88.2%。与2.0%Ru/Si_(3)N_(4)相比,2.0%Ru/Si_(3)N_(4)-C的金属粒径更大,活性位点较少,活性更低。2.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)-C的CO_(2)转化率分别为53.1%和9.2%。Si_(3)N_(4)有效提高了金属分散度,提高了催化剂的CO_(2)加氢反应活性;通过调控Ru负载量控制催化剂金属粒径,可实现对产物CO或CH_(4)选择性的调控。展开更多
TiO_(2) nanobelts and Co_(3)O_(4)/TiO_(2) catalytic materials were prepared using the hydrothermal method.The cat-alyst was characterized by X-ray diffraction,scanning electron microscopy,transmission electron microsc...TiO_(2) nanobelts and Co_(3)O_(4)/TiO_(2) catalytic materials were prepared using the hydrothermal method.The cat-alyst was characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,X-ray electron spectroscopy,and fluorescence spectroscopy.At room temperature,with a relative humidity of 50.0%,the total gas flow rate of 1.0 L·min-1,the space velocity of 1.05×10^(4) h^(-1),and toluene volume concentration of 25.0µL·L^(-1),two 6 W vacuum ultraviolet lamps were used as light sources to catalyze,degrade,and mineralize toluene.The results show that the prepared catalyst is in the shape of nano-ribbons.The loading of Co_(3)O_(4) inhibits the recombina-tion of photogenerated electrons and holes and can effectively improve the catalytic performance.The Co_(3)O_(4)/TiO_(2) with a load of 6.0%Co_(3)O_(4) has the best catalytic effect.When N2 was used as a carrier gas,the degradation rate of tol-uene was only 34.7%.The toluene degradation is mainly due to the photolysis of vacuum ultraviolet light.When air was used as a carrier gas,O_(3) was produced.The Co_(3)O_(4)/TiO_(2) with a load of 6.0%and vacuum ultraviolet synergistical-ly promote toluene degradation.The highest degradation rate of toluene was 91.7%and the mineralization rate was 74.6%.The degradation rate of toluene was 2.6 times that of nitrogen as a carrier gas.展开更多
Reforming CO_(2)into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage.Unfortunately,the problem of rapid photogenerated car...Reforming CO_(2)into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage.Unfortunately,the problem of rapid photogenerated carriers severely limits the CO_(2)reduction capability of one-component catalysts.The fabrication of S-scheme heterojunctions with defects can result in efficient spatial separation of photo-generated charge carriers and increase adsorption and activation of nonpolar molecules.Herein,ZnWO_(4)/g-C_(3)N_(4)S-scheme heterojunctions with defects are constructed through in situ growth method.The experiments show that the generation rate of CO from CO_(2)reduction is up to 232.4μmol∙g^(−1)∙h^(−1)with a selectivity close to 100%,which is 11.6 and 8.5 times higher than those of pristine ZnWO_(4)and g-C_(3)N_(4),respectively.In situ XPS and work function analyses demonstrate the S-scheme charge transport pathway,which facilitates the spatial segregation of photogenerated carriers and promotes CO_(2)reduction.In situ ESR illustrates that CO_(2)molecules are adsorbed by nitrogen vacancies,which act as photoelectron acceptors during the photocatalytic reaction and are favorable for charge trapping and separation.The S-scheme charge transport mode and nitrogen vacancy work together to stimulate the efficient conversion of CO_(2)to CO.This work presents significant insights to the cooperative influence of the S-scheme charge transport mode and defects in regulating CO_(2)reduction activity.展开更多
The use of carbon-based fuels causes a significant increase in CO_(2)emissions,posing a serious threat to the environment.This review explores the potential application of graphitic carbon nitride(g-C_(3)N_(4))in phot...The use of carbon-based fuels causes a significant increase in CO_(2)emissions,posing a serious threat to the environment.This review explores the potential application of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic CO_(2)reduction as a strategy to mitigate global warming.The effectiveness of g-C_(3)N_(4)(gCN)in this process is hindered by several factors,including rapid exciton recombination,limited solar light absorption,and a lack of active sites for conducting the reduction.To address these challenges,various amendment techniques have been executed,such as adjusting the morphology of g-C_(3)N_(4),doping it with different atoms,and forming heterojunctions with other semiconductors.This review highlights the role of S-scheme heterojunctions in expanding the photocatalytic activity of g-C_(3)N_(4)and emphasizes that,despite its potential as a photocatalyst for CO_(2)reduction,further research and innovation are essential to overcome its current limitations.展开更多
文摘氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过浸渍法制备了不同Ru负载量(质量分数分别为0.5%、1.0%和2.0%)的催化剂(分别为0.5%Ru/Si_(3)N_(4)、1.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)),并以商品氮化硅(Si_(3)N_(4)-C)为载体制备了2.0%Ru/Si_(3)N_(4)-C催化剂作为对照组。表征了催化剂的理化性质,测试了其在300℃、0.1 MPa下的CO_(2)加氢反应活性。结果显示,与Si_(3)N_(4)-C相比,Si_(3)N_(4)的比表面积较高(502 m^(2)/g),Si_(3)N_(4)作为载体显著提高了金属分散度,降低了金属粒径,催化剂暴露出更多的活性位点。0.5%Ru/Si_(3)N_(4)的金属粒径较小,展现出强的H_(2)吸附能力,H难以解吸,抑制了中间物种CO加氢生成CH_(4)。随着Ru负载量增加,金属粒径增大,催化剂的CH_(4)选择性更好。Ru/Si_(3)N_(4)系列催化剂中,2.0%Ru/Si_(3)N_(4)的CH_(4)选择性较高(98.8%)。空速为10000 m L/(g·h)时,0.5%Ru/Si_(3)N_(4)的CO选择性为88.2%。与2.0%Ru/Si_(3)N_(4)相比,2.0%Ru/Si_(3)N_(4)-C的金属粒径更大,活性位点较少,活性更低。2.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)-C的CO_(2)转化率分别为53.1%和9.2%。Si_(3)N_(4)有效提高了金属分散度,提高了催化剂的CO_(2)加氢反应活性;通过调控Ru负载量控制催化剂金属粒径,可实现对产物CO或CH_(4)选择性的调控。
文摘TiO_(2) nanobelts and Co_(3)O_(4)/TiO_(2) catalytic materials were prepared using the hydrothermal method.The cat-alyst was characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,X-ray electron spectroscopy,and fluorescence spectroscopy.At room temperature,with a relative humidity of 50.0%,the total gas flow rate of 1.0 L·min-1,the space velocity of 1.05×10^(4) h^(-1),and toluene volume concentration of 25.0µL·L^(-1),two 6 W vacuum ultraviolet lamps were used as light sources to catalyze,degrade,and mineralize toluene.The results show that the prepared catalyst is in the shape of nano-ribbons.The loading of Co_(3)O_(4) inhibits the recombina-tion of photogenerated electrons and holes and can effectively improve the catalytic performance.The Co_(3)O_(4)/TiO_(2) with a load of 6.0%Co_(3)O_(4) has the best catalytic effect.When N2 was used as a carrier gas,the degradation rate of tol-uene was only 34.7%.The toluene degradation is mainly due to the photolysis of vacuum ultraviolet light.When air was used as a carrier gas,O_(3) was produced.The Co_(3)O_(4)/TiO_(2) with a load of 6.0%and vacuum ultraviolet synergistical-ly promote toluene degradation.The highest degradation rate of toluene was 91.7%and the mineralization rate was 74.6%.The degradation rate of toluene was 2.6 times that of nitrogen as a carrier gas.
文摘Reforming CO_(2)into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage.Unfortunately,the problem of rapid photogenerated carriers severely limits the CO_(2)reduction capability of one-component catalysts.The fabrication of S-scheme heterojunctions with defects can result in efficient spatial separation of photo-generated charge carriers and increase adsorption and activation of nonpolar molecules.Herein,ZnWO_(4)/g-C_(3)N_(4)S-scheme heterojunctions with defects are constructed through in situ growth method.The experiments show that the generation rate of CO from CO_(2)reduction is up to 232.4μmol∙g^(−1)∙h^(−1)with a selectivity close to 100%,which is 11.6 and 8.5 times higher than those of pristine ZnWO_(4)and g-C_(3)N_(4),respectively.In situ XPS and work function analyses demonstrate the S-scheme charge transport pathway,which facilitates the spatial segregation of photogenerated carriers and promotes CO_(2)reduction.In situ ESR illustrates that CO_(2)molecules are adsorbed by nitrogen vacancies,which act as photoelectron acceptors during the photocatalytic reaction and are favorable for charge trapping and separation.The S-scheme charge transport mode and nitrogen vacancy work together to stimulate the efficient conversion of CO_(2)to CO.This work presents significant insights to the cooperative influence of the S-scheme charge transport mode and defects in regulating CO_(2)reduction activity.
文摘The use of carbon-based fuels causes a significant increase in CO_(2)emissions,posing a serious threat to the environment.This review explores the potential application of graphitic carbon nitride(g-C_(3)N_(4))in photocatalytic CO_(2)reduction as a strategy to mitigate global warming.The effectiveness of g-C_(3)N_(4)(gCN)in this process is hindered by several factors,including rapid exciton recombination,limited solar light absorption,and a lack of active sites for conducting the reduction.To address these challenges,various amendment techniques have been executed,such as adjusting the morphology of g-C_(3)N_(4),doping it with different atoms,and forming heterojunctions with other semiconductors.This review highlights the role of S-scheme heterojunctions in expanding the photocatalytic activity of g-C_(3)N_(4)and emphasizes that,despite its potential as a photocatalyst for CO_(2)reduction,further research and innovation are essential to overcome its current limitations.
