Ammonia is one of the most important chemical raw materials in both manufacture and life of human.Traditionally Haber-Bosch method for ammonia synthesis involves high temperature and high pressure conditions,leading t...Ammonia is one of the most important chemical raw materials in both manufacture and life of human.Traditionally Haber-Bosch method for ammonia synthesis involves high temperature and high pressure conditions,leading to significant energy consumption and environmental pollution.Non-thermal plasma(NTP) is a promising alternative approach to ammonia synthesis at low temperature and atmospheric pressure.In this study,the synergistic effect of nanosecond pulsed dielectric barrier discharge(np-DBD) and Ni-MOF-74 catalyst was investigated in ammonia synthesis by utilizing nitrogen and hydrogen as feedstock.The results demonstrated that the plasma catalytic-synthesis process parameters play a crucial role in the synthesis process of ammonia.The highest ammonia synthesis rate of 5145.16 μmol·g^(-1)·h^(-1)with an energy efficiency of 1.27 g·kWh^(-1)was observed in the presence of the Ni-MOF-74 catalyst,which was3.7 times higher than that without Ni-MOF-74 catalyst.The synergistic effect of Ni-MOF-74catalyst and nanosecond pulsed plasma was explored by in-situ plasma discharge diagnostics.展开更多
Metal–organic frameworks(MOFs)and layered double hydroxides(LDHs)have been considered to be one of the most promising and worthy hot spot materials to develop advanced catalysts for effi cient hydrogen evolution due ...Metal–organic frameworks(MOFs)and layered double hydroxides(LDHs)have been considered to be one of the most promising and worthy hot spot materials to develop advanced catalysts for effi cient hydrogen evolution due to their prominent characteristics,including unique structures,environmentally friendly nature,high redox activities,and homogeneously eff ective utilization of transition metal atoms.In this work,the delicate S-scheme heterojunction photocatalyst,CoAl LDH@Ni-MOF-74,was rationally designed and successfully constructed by coupling Ni-MOF-74 with CoAl LDH based on their peculiar structure,excellent electronic properties,and opposite surface potential for enhancing hydrogen generation activity under visible light irradiation.The CoAl LDH nanolayers evenly and dispersedly load on the surface of Ni-MOF-74.The CoAl LDH@Ni-MOF-74 exhibited higher photocatalytic hydrogen evolution activity compared with Ni-MOF-74 and CoAl LDH alone,mainly because the formation of the CoAl LDH@Ni-MOF-74 S-scheme heterojunction accelerated the recombination of several electrons(from conduction band(CB)of Ni-MOF-74)and holes(from valence band(VB)of CoAl LDH)and prevented the recombination of other electrons(from CB of CoAl LDH)and holes(from VB of Ni-MOF-74).展开更多
采用水热法成功制备了MOF-74(Ni),使用PXRD、孔径分析对材料进行了表征,测定了材料在不同温度下的C_3H_6和C_3H_8吸附等温线,应用程序升温脱附技术估算了脱附活化能,并使用IAST理论预测了材料对C_3H_6/C_3H_8二元体系的吸附选择性。讨...采用水热法成功制备了MOF-74(Ni),使用PXRD、孔径分析对材料进行了表征,测定了材料在不同温度下的C_3H_6和C_3H_8吸附等温线,应用程序升温脱附技术估算了脱附活化能,并使用IAST理论预测了材料对C_3H_6/C_3H_8二元体系的吸附选择性。讨论了温度对吸附机理和吸附选择性的影响。结果显示,MOF-74(Ni)的BET比表面积高达1306 m2·g^(-1)。在298 K下,C_3H_6的吸附量高达7.4 mmol·g^(-1)。随着温度升高,C_3H_8的吸附量大幅降低,而C_3H_6的吸附量下降程度较小,导致材料对C_3H_6/C_3H_8吸附选择性升高。当温度为328K时,MOF-74(Ni)对C_3H_6/C_3H_8二元气体混合物的吸附选择接近12。程序升温脱附的实验结果显示,C_3H_6在MOF-74(Ni)上的脱附活化能大于C_3H_8,分别为68.92 k J·mol^(-1)和50.80 k J·mol^(-1)。C_3H_6是通过与MOF-74(Ni)的不饱和金属位点Ni2+以π络合作用方式吸附,作用力较强,而C_3H_8与Ni2+之间的作用力较弱。根据吸附机理不同的特点,适当提高温度,将有助于提高MOF-74(Ni)吸附分离C_3H_6/C_3H_8混合物体系的吸附选择性。展开更多
基金the financial support from the Beijing Municipal Natural Science Foundation (No. 1242015)National Undergraduate Innovation and Entrepreneurship Training Program of China (No. 202310015019)Discipline Construction of Material Science and Engineering(Nos. 21090122014 and 21090123007)。
文摘Ammonia is one of the most important chemical raw materials in both manufacture and life of human.Traditionally Haber-Bosch method for ammonia synthesis involves high temperature and high pressure conditions,leading to significant energy consumption and environmental pollution.Non-thermal plasma(NTP) is a promising alternative approach to ammonia synthesis at low temperature and atmospheric pressure.In this study,the synergistic effect of nanosecond pulsed dielectric barrier discharge(np-DBD) and Ni-MOF-74 catalyst was investigated in ammonia synthesis by utilizing nitrogen and hydrogen as feedstock.The results demonstrated that the plasma catalytic-synthesis process parameters play a crucial role in the synthesis process of ammonia.The highest ammonia synthesis rate of 5145.16 μmol·g^(-1)·h^(-1)with an energy efficiency of 1.27 g·kWh^(-1)was observed in the presence of the Ni-MOF-74 catalyst,which was3.7 times higher than that without Ni-MOF-74 catalyst.The synergistic effect of Ni-MOF-74catalyst and nanosecond pulsed plasma was explored by in-situ plasma discharge diagnostics.
基金This work was financially supported by the Natural Science Foundation of the Ningxia Hui Autonomous Region(No.2020AAC02026).
文摘Metal–organic frameworks(MOFs)and layered double hydroxides(LDHs)have been considered to be one of the most promising and worthy hot spot materials to develop advanced catalysts for effi cient hydrogen evolution due to their prominent characteristics,including unique structures,environmentally friendly nature,high redox activities,and homogeneously eff ective utilization of transition metal atoms.In this work,the delicate S-scheme heterojunction photocatalyst,CoAl LDH@Ni-MOF-74,was rationally designed and successfully constructed by coupling Ni-MOF-74 with CoAl LDH based on their peculiar structure,excellent electronic properties,and opposite surface potential for enhancing hydrogen generation activity under visible light irradiation.The CoAl LDH nanolayers evenly and dispersedly load on the surface of Ni-MOF-74.The CoAl LDH@Ni-MOF-74 exhibited higher photocatalytic hydrogen evolution activity compared with Ni-MOF-74 and CoAl LDH alone,mainly because the formation of the CoAl LDH@Ni-MOF-74 S-scheme heterojunction accelerated the recombination of several electrons(from conduction band(CB)of Ni-MOF-74)and holes(from valence band(VB)of CoAl LDH)and prevented the recombination of other electrons(from CB of CoAl LDH)and holes(from VB of Ni-MOF-74).
文摘采用水热法成功制备了MOF-74(Ni),使用PXRD、孔径分析对材料进行了表征,测定了材料在不同温度下的C_3H_6和C_3H_8吸附等温线,应用程序升温脱附技术估算了脱附活化能,并使用IAST理论预测了材料对C_3H_6/C_3H_8二元体系的吸附选择性。讨论了温度对吸附机理和吸附选择性的影响。结果显示,MOF-74(Ni)的BET比表面积高达1306 m2·g^(-1)。在298 K下,C_3H_6的吸附量高达7.4 mmol·g^(-1)。随着温度升高,C_3H_8的吸附量大幅降低,而C_3H_6的吸附量下降程度较小,导致材料对C_3H_6/C_3H_8吸附选择性升高。当温度为328K时,MOF-74(Ni)对C_3H_6/C_3H_8二元气体混合物的吸附选择接近12。程序升温脱附的实验结果显示,C_3H_6在MOF-74(Ni)上的脱附活化能大于C_3H_8,分别为68.92 k J·mol^(-1)和50.80 k J·mol^(-1)。C_3H_6是通过与MOF-74(Ni)的不饱和金属位点Ni2+以π络合作用方式吸附,作用力较强,而C_3H_8与Ni2+之间的作用力较弱。根据吸附机理不同的特点,适当提高温度,将有助于提高MOF-74(Ni)吸附分离C_3H_6/C_3H_8混合物体系的吸附选择性。
