化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“...化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“钴-氮-碳”(Co-N-C/P)催化剂,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对催化剂的形貌、元素分布、缺陷程度、表面元素价态及配位结构进行了表征,并考察了其在H型电解槽中电催化CO_(2)还原为CO的性能。测试结果表明,所制备的Co-N-C/P催化剂在-0.9 V vs.RHE的外加电位下具有97.0%的CO法拉第效率(FE_(CO)),电流密度为4.58 mA/cm^(2),并可以进行26 h的稳定性测试。与Co-N-C催化剂相比,P的掺杂更有利于Co原子在碳黑基底上的良好分散,相应的FE_(CO)提高了约38.9%,说明P的掺杂有效提高了Co-N-C催化剂的电催化CO_(2)还原为CO的性能。展开更多
Pot grown alfalfa (Medicago sativa L.) were experimented in the open top chambers in which natural air(350×10 -6 ,1×CO 2) and doubled CO 2 air(700×10 -6 ,2×CO 2) were continuous blown through botto...Pot grown alfalfa (Medicago sativa L.) were experimented in the open top chambers in which natural air(350×10 -6 ,1×CO 2) and doubled CO 2 air(700×10 -6 ,2×CO 2) were continuous blown through bottom respectively.Results showed that the biomass in both shoot and root was increased by the 2×CO 2 treatment.The root/shoot ratio was nearly unchange in the short term treatment and slightly decreased in the longer term treatment.The results differed from those reported in literatures that was attributed to the pot grown condition in this experiment.The nitrogen fixation activities(acetylene reduction) per plant were obviously promoted under the 2×CO 2 condition but the difference of the specific nitrogen fixing activities between 1×CO 2 and 2×CO 2 treatment was small.It implied that supplement of ATP,NADP or carbon skeleton under the 2×CO 2 condition was not more than that under the 1×CO 2 condition. C/N ratio in the shoot increased in the doubled CO 2 treatment group,similar to the reports from other authors;but the ratio increased in the root in the 2×CO 2 treatment group was ascribed to the higher nitrogen absorption from the soil and(or) N fixing activity of the nodules as compared with that in the 1×CO 2 treatment.The results demonstrated that assimilation and allocation of carbon and nitrogen in legume plant were deeply influenced by the elevated CO 2.展开更多
文摘化石燃料的燃烧导致大气中二氧化碳(CO_(2))的浓度迅速上升,并引发了严重的能源、环境危机。由可再生电力驱动的电催化CO_(2)还原为增值化学品和燃料是解决当前化石燃料枯竭的一种有效方法。采用“一锅法”制备了磷(P)修饰的高分散性“钴-氮-碳”(Co-N-C/P)催化剂,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)和X射线光电子能谱(XPS)等手段对催化剂的形貌、元素分布、缺陷程度、表面元素价态及配位结构进行了表征,并考察了其在H型电解槽中电催化CO_(2)还原为CO的性能。测试结果表明,所制备的Co-N-C/P催化剂在-0.9 V vs.RHE的外加电位下具有97.0%的CO法拉第效率(FE_(CO)),电流密度为4.58 mA/cm^(2),并可以进行26 h的稳定性测试。与Co-N-C催化剂相比,P的掺杂更有利于Co原子在碳黑基底上的良好分散,相应的FE_(CO)提高了约38.9%,说明P的掺杂有效提高了Co-N-C催化剂的电催化CO_(2)还原为CO的性能。
文摘Pot grown alfalfa (Medicago sativa L.) were experimented in the open top chambers in which natural air(350×10 -6 ,1×CO 2) and doubled CO 2 air(700×10 -6 ,2×CO 2) were continuous blown through bottom respectively.Results showed that the biomass in both shoot and root was increased by the 2×CO 2 treatment.The root/shoot ratio was nearly unchange in the short term treatment and slightly decreased in the longer term treatment.The results differed from those reported in literatures that was attributed to the pot grown condition in this experiment.The nitrogen fixation activities(acetylene reduction) per plant were obviously promoted under the 2×CO 2 condition but the difference of the specific nitrogen fixing activities between 1×CO 2 and 2×CO 2 treatment was small.It implied that supplement of ATP,NADP or carbon skeleton under the 2×CO 2 condition was not more than that under the 1×CO 2 condition. C/N ratio in the shoot increased in the doubled CO 2 treatment group,similar to the reports from other authors;but the ratio increased in the root in the 2×CO 2 treatment group was ascribed to the higher nitrogen absorption from the soil and(or) N fixing activity of the nodules as compared with that in the 1×CO 2 treatment.The results demonstrated that assimilation and allocation of carbon and nitrogen in legume plant were deeply influenced by the elevated CO 2.
