In this study,a MnOx@TiO2 core‐shell catalyst prepared by a two‐step method was used for the low‐temperature selective catalytic reduction of NOx with NH3.The catalyst exhibits high activity,high stability,and exce...In this study,a MnOx@TiO2 core‐shell catalyst prepared by a two‐step method was used for the low‐temperature selective catalytic reduction of NOx with NH3.The catalyst exhibits high activity,high stability,and excellent N2 selectivity.Furthermore,it displays better SO2 and H2O tolerance than its MnOx,TiO2,and MnOx/TiO2 counterparts.The prepared catalyst was characterized systematically by transmission electron microscopy,high‐resolution transmission electron microscopy,X‐ray diffraction,Raman,BET,X‐ray photoelectron spectroscopy,NH3 temperature‐programmed desorption and H2 temperature‐programmed reduction analyses.The optimized MnOx@TiO2 catalyst exhibits an obvious core‐shell structure,where the TiO2 shell is evenly distributed over the MnOx nanorod core.The catalyst also presents abundant mesopores,Lewis‐acid sites,and high redox capability,all of which enhance its catalytic performance.According to the XPS results,the decrease in the number of Mn4+active centers after SO2 poisoning is significantly lower in MnOx@TiO2 than in MnOx/TiO2.The core‐shell structure is hence able to protect the catalytic active sites from H2O and SO2 poisoning.展开更多
在金纳米棒(AuNRs)-Ag^+-甲醛(HCHO)体系中,HCHO快速将Ag^+还原为Ag,Ag包裹在AuNRs表面形成Au@AgNRs,改变了AuNRs周围的电介质环境,导致纵向最大吸收波长(LPAB)红移,同时伴随着溶液的颜色发生显著的变化。据此,发展了一种测定HCHO的快...在金纳米棒(AuNRs)-Ag^+-甲醛(HCHO)体系中,HCHO快速将Ag^+还原为Ag,Ag包裹在AuNRs表面形成Au@AgNRs,改变了AuNRs周围的电介质环境,导致纵向最大吸收波长(LPAB)红移,同时伴随着溶液的颜色发生显著的变化。据此,发展了一种测定HCHO的快响应、简便、灵敏、选择性的AuNRs比色传感器。该比色传感器的检出限为6.3×10^(-11)(g m L^(-1)),比表面增强拉曼光谱法低,显示很高的灵敏度;尤其是本比色传感器用于水样品中HCHO的测定,结果与固体基质室温磷光法相吻合,展示较高的实用性。此外,探讨了测定HCHO的机理。展开更多
文摘In this study,a MnOx@TiO2 core‐shell catalyst prepared by a two‐step method was used for the low‐temperature selective catalytic reduction of NOx with NH3.The catalyst exhibits high activity,high stability,and excellent N2 selectivity.Furthermore,it displays better SO2 and H2O tolerance than its MnOx,TiO2,and MnOx/TiO2 counterparts.The prepared catalyst was characterized systematically by transmission electron microscopy,high‐resolution transmission electron microscopy,X‐ray diffraction,Raman,BET,X‐ray photoelectron spectroscopy,NH3 temperature‐programmed desorption and H2 temperature‐programmed reduction analyses.The optimized MnOx@TiO2 catalyst exhibits an obvious core‐shell structure,where the TiO2 shell is evenly distributed over the MnOx nanorod core.The catalyst also presents abundant mesopores,Lewis‐acid sites,and high redox capability,all of which enhance its catalytic performance.According to the XPS results,the decrease in the number of Mn4+active centers after SO2 poisoning is significantly lower in MnOx@TiO2 than in MnOx/TiO2.The core‐shell structure is hence able to protect the catalytic active sites from H2O and SO2 poisoning.
文摘在金纳米棒(AuNRs)-Ag^+-甲醛(HCHO)体系中,HCHO快速将Ag^+还原为Ag,Ag包裹在AuNRs表面形成Au@AgNRs,改变了AuNRs周围的电介质环境,导致纵向最大吸收波长(LPAB)红移,同时伴随着溶液的颜色发生显著的变化。据此,发展了一种测定HCHO的快响应、简便、灵敏、选择性的AuNRs比色传感器。该比色传感器的检出限为6.3×10^(-11)(g m L^(-1)),比表面增强拉曼光谱法低,显示很高的灵敏度;尤其是本比色传感器用于水样品中HCHO的测定,结果与固体基质室温磷光法相吻合,展示较高的实用性。此外,探讨了测定HCHO的机理。
