Flower-like copper foam Co_(3)O_(4) catalysts(Co_(3)O_(4)/CF) were prepared by hydrothermal method.The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffrac...Flower-like copper foam Co_(3)O_(4) catalysts(Co_(3)O_(4)/CF) were prepared by hydrothermal method.The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffractometer(XRD) and scanning electron microscope(SEM),and the electrochemical properties were investigated by an electrochemical workstation.The experimental results show that the Co_(3)O_(4) catalysts are successfully prepared on the foamed copper support by hydrothermal method,and the material’s morphology is mainly flower cluster.When the current density is 10 mA·cm^(-2),the overpotential value of the Co_(3)O_(4)/CF catalyst is 141 mV,lower than that of blank support.The electrochemical impedance(EIS) spectrum shows that the R_(ct )value of the Co_(3)O_(4)/CF catalyst decreases,and the Coulomb curves of double-layer show that the electrochemically active area of the Co_(3)O_(4)/CF catalyst efficiently increases compared with that of the blank support.Therefore,the as-obtained Co_(3)O_(4)/CF catalyst exhibits a good hydrogen evolution rate,showing great applicability potential in the catalytic electrolysis of water for hydrogen production.展开更多
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
The Co_(3)O_(4)nanoparticles,dominated by a catalytically active(110)lattice plane,were synthesized as a low-temperature NO_(x) adsorbent to control the cold start emissions from vehicles.These nanoparticles boast a s...The Co_(3)O_(4)nanoparticles,dominated by a catalytically active(110)lattice plane,were synthesized as a low-temperature NO_(x) adsorbent to control the cold start emissions from vehicles.These nanoparticles boast a substantial quantity of active chemisorbed oxygen and lattice oxygen,which exhibited a NO_(x) uptake capacity commensurate with Pd/SSZ-13 at 100℃.The primary NO_(x) release temperature falls within a temperature range of 200-350℃,making it perfectly suitable for diesel engines.The characterization results demonstrate that chemisorbed oxygen facilitate nitro/nitrites intermediates formation,contributing to the NO_(x) storage at 100℃,while the nitrites begin to decompose within the 150-200℃range.Fortunately,lattice oxygen likely becomes involved in the activation of nitrites into more stable nitrate within this particular temperature range.The concurrent processes of nitrites decomposition and its conversion to nitrates results in a minimal NO_(x) release between the temperatures of 150-200℃.The nitrate formed via lattice oxygen mainly induces the NO_(x) to be released as NO_(2) within a temperature range of 200-350℃,which is advantageous in enhancing the NO_(x) activity of downstream NH_(3)-SCR catalysts,by boosting the fast SCR reaction pathway.Thanks to its low cost,considerable NO_(x) absorption capacity,and optimal release temperature,Co_(3)O_(4)demonstrates potential as an effective material for passive NO_(x) adsorber applications.展开更多
基金Funded by the National Natural Science Foundation of China(No.51474170)the Foundation of Shaanxi Educational Committee(No.17JK0395)the Xi’an Science and Technology Committee Program(No.GXYD9.2)。
文摘Flower-like copper foam Co_(3)O_(4) catalysts(Co_(3)O_(4)/CF) were prepared by hydrothermal method.The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffractometer(XRD) and scanning electron microscope(SEM),and the electrochemical properties were investigated by an electrochemical workstation.The experimental results show that the Co_(3)O_(4) catalysts are successfully prepared on the foamed copper support by hydrothermal method,and the material’s morphology is mainly flower cluster.When the current density is 10 mA·cm^(-2),the overpotential value of the Co_(3)O_(4)/CF catalyst is 141 mV,lower than that of blank support.The electrochemical impedance(EIS) spectrum shows that the R_(ct )value of the Co_(3)O_(4)/CF catalyst decreases,and the Coulomb curves of double-layer show that the electrochemically active area of the Co_(3)O_(4)/CF catalyst efficiently increases compared with that of the blank support.Therefore,the as-obtained Co_(3)O_(4)/CF catalyst exhibits a good hydrogen evolution rate,showing great applicability potential in the catalytic electrolysis of water for hydrogen production.
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。
基金supported by the National Natural Science Foundation of China(22006044,22006043)External Cooperation Program of Science and Technology Planning of Fujian Province(2023I0018)+2 种基金the Fujian Province Science and Technology Program Funds(2020H6013)the National Engineering Laboratory for Mobile Source Emission Control Technology(NELMS2020A03)the Scientific Research Funds of Huaqiao University(605-50Y200270001)。
文摘The Co_(3)O_(4)nanoparticles,dominated by a catalytically active(110)lattice plane,were synthesized as a low-temperature NO_(x) adsorbent to control the cold start emissions from vehicles.These nanoparticles boast a substantial quantity of active chemisorbed oxygen and lattice oxygen,which exhibited a NO_(x) uptake capacity commensurate with Pd/SSZ-13 at 100℃.The primary NO_(x) release temperature falls within a temperature range of 200-350℃,making it perfectly suitable for diesel engines.The characterization results demonstrate that chemisorbed oxygen facilitate nitro/nitrites intermediates formation,contributing to the NO_(x) storage at 100℃,while the nitrites begin to decompose within the 150-200℃range.Fortunately,lattice oxygen likely becomes involved in the activation of nitrites into more stable nitrate within this particular temperature range.The concurrent processes of nitrites decomposition and its conversion to nitrates results in a minimal NO_(x) release between the temperatures of 150-200℃.The nitrate formed via lattice oxygen mainly induces the NO_(x) to be released as NO_(2) within a temperature range of 200-350℃,which is advantageous in enhancing the NO_(x) activity of downstream NH_(3)-SCR catalysts,by boosting the fast SCR reaction pathway.Thanks to its low cost,considerable NO_(x) absorption capacity,and optimal release temperature,Co_(3)O_(4)demonstrates potential as an effective material for passive NO_(x) adsorber applications.
