The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMC...The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.展开更多
Electrosynthesis of hydrogen peroxide(H2O2)is an on-site method that enables independent distribution applications in many fields due to its small-scale and sustainable features.The crucial point remains developing hi...Electrosynthesis of hydrogen peroxide(H2O2)is an on-site method that enables independent distribution applications in many fields due to its small-scale and sustainable features.The crucial point remains developing highly active,selective and cost-effective electrocatalysts.The electrosynthesis of H2O2 in acidic media is more practical owing to its stability and no need for further purification.We herein report a phosphorus and selenium tuning Co-based non-precious catalyst(CoPSe)toward two-electron oxygen reduction reaction(2e–ORR)to produce H2O2 in acidic media.The starting point of using both P and Se is finding a balance between strong ORR activity of CoSe and weak activity of CoP.The results demonstrated that the CoPSe catalyst exhibited the optimized 2e–ORR activity compared with CoP and CoSe.It disclosed an onset potential of 0.68 V and the H2O2 selectivity 76%-85%in a wide potential range(0–0.5 V).Notably,the CoPSe catalyst overcomes a significant challenge of a narrow-range selectivity for transitionmetal based 2e–ORR catalysts.Finally,combining with electro-Fenton reaction,an on-site system was constructed for efficient degradation of organic pollutants.This work provides a promising non-precious Co-based electrocatalyst for the electrosynthesis of H2O2 in acidic media.展开更多
Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multicarbon products is an efficient approach for ad-dressing the energy crisis and achieving carbon neutrality.In H-cells,achieving high-current C_(2)products is chall...Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multicarbon products is an efficient approach for ad-dressing the energy crisis and achieving carbon neutrality.In H-cells,achieving high-current C_(2)products is challenging because of the inefficient mass transfer of the catalyst and the presence of the hydrogen evolution reaction(HER).In this study,dendritic Cu/Cu_(2)O with abundant Cu^(0)/Cu^(+)interfaces and numerous dendritic curves was synthesized in a CO_(2)atmosphere,resulting in the high selectivity and current density of the C_(2)products.Dendritic Cu/Cu_(2)O achieved a C_(2)Faradaic efficiency of 69.8%and a C_(2)partial current density of 129.5 mA cm^(-2)in an H-cell.Finite element simulations showed that a dendritic structure with a high curvature generates a strong electric field,leading to a localized CO_(2)concentration.Additionally,DRT analysis showed that a dendritic struc-ture with a high curvature actively adsorbed the surrounding high concentration of CO_(2),enhancing the mass transfer rate and achieving a high current density.During the experiment,the impact of the electronic structure on the performance of the catalyst was investigated by varying the atomic ratio of Cu^(0)/Cu^(+) on the catalyst surface,which resulted in improved ethylene selectivity.Under the optimal atomic ratio of Cu^(0)/Cu^(+),the charge transfer resistance was minimized,and the desorption rate of the intermediates was low,favoring C_(2) generation.Density functional theory calculations indicated that the Cu^(0)/Cu^(+) interfaces exhibited a lower Gibbs free energy for the rate-determining step,enhancing C_(2)H_(4) formation.The Cu/Cu_(2)O catalyst also exhibited a low Cu d-band center,which enhanced the adsorption stability of *CO on the surface and facilitated C_(2)formation.This observa-tion explained the higher yield of C_(2) products at the Cu^(0)/Cu^(+) interface than that of H_(2) under rapid mass transfer.The results of the net present value model showed that the H-cell holds promising industrial prospects,contingent upon it being a catalyst with both high selectivity and high current density.This approach of integrating the structure and composition provides new insights for ad-vancing the CO_(2)RR towards high-current C_(2) products.展开更多
V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for N...V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.展开更多
将厌氧发酵残留物作为肥料还田是其资源化利用的有效途径，但国内外对其还田后氨气（NH3）和氧化亚氮（N2O）的排放特征及氮素利用率的报道较少。本研究通过微区试验，探讨了冬季和夏季大棚菜地追施猪粪沼液（DPS）后NH3和N2O的排放速...将厌氧发酵残留物作为肥料还田是其资源化利用的有效途径，但国内外对其还田后氨气（NH3）和氧化亚氮（N2O）的排放特征及氮素利用率的报道较少。本研究通过微区试验，探讨了冬季和夏季大棚菜地追施猪粪沼液（DPS）后NH3和N2O的排放速率及氮素损失率。结果发现， 追施DPS后菜地NH3挥发激增，通常发生在施肥后的48 h 内；而N2O排放量在第一次施肥后大幅增加，随后逐步趋于稳定。追施DPS的处理其NH3和N2O的排放量均显著高于施用化肥的处理，冬季和夏季二者的损失量分别占肥料总量的16.4%～23.2%和24.7%～27.5%。土壤温度、水分和pH对沼液中氮素以NH3和N2O的形式损失的影响较大。展开更多
文摘The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.
基金the National Natural Science Foundation of China(Nos.21805052,21974031,2278092)Science and Technology Research Project of Guangzhou(Nos.202102020787 and 202201000002)+2 种基金Department of Science&Technology of Guangdong Province(No.2022A156)Key Discipline of Materials Science and Engineering,Bureau of Education of Guangzhou(No.20225546)the Innovation&Entrepreneurship for the College Students of Guangzhou University(No.XJ202111078175).
文摘Electrosynthesis of hydrogen peroxide(H2O2)is an on-site method that enables independent distribution applications in many fields due to its small-scale and sustainable features.The crucial point remains developing highly active,selective and cost-effective electrocatalysts.The electrosynthesis of H2O2 in acidic media is more practical owing to its stability and no need for further purification.We herein report a phosphorus and selenium tuning Co-based non-precious catalyst(CoPSe)toward two-electron oxygen reduction reaction(2e–ORR)to produce H2O2 in acidic media.The starting point of using both P and Se is finding a balance between strong ORR activity of CoSe and weak activity of CoP.The results demonstrated that the CoPSe catalyst exhibited the optimized 2e–ORR activity compared with CoP and CoSe.It disclosed an onset potential of 0.68 V and the H2O2 selectivity 76%-85%in a wide potential range(0–0.5 V).Notably,the CoPSe catalyst overcomes a significant challenge of a narrow-range selectivity for transitionmetal based 2e–ORR catalysts.Finally,combining with electro-Fenton reaction,an on-site system was constructed for efficient degradation of organic pollutants.This work provides a promising non-precious Co-based electrocatalyst for the electrosynthesis of H2O2 in acidic media.
文摘Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multicarbon products is an efficient approach for ad-dressing the energy crisis and achieving carbon neutrality.In H-cells,achieving high-current C_(2)products is challenging because of the inefficient mass transfer of the catalyst and the presence of the hydrogen evolution reaction(HER).In this study,dendritic Cu/Cu_(2)O with abundant Cu^(0)/Cu^(+)interfaces and numerous dendritic curves was synthesized in a CO_(2)atmosphere,resulting in the high selectivity and current density of the C_(2)products.Dendritic Cu/Cu_(2)O achieved a C_(2)Faradaic efficiency of 69.8%and a C_(2)partial current density of 129.5 mA cm^(-2)in an H-cell.Finite element simulations showed that a dendritic structure with a high curvature generates a strong electric field,leading to a localized CO_(2)concentration.Additionally,DRT analysis showed that a dendritic struc-ture with a high curvature actively adsorbed the surrounding high concentration of CO_(2),enhancing the mass transfer rate and achieving a high current density.During the experiment,the impact of the electronic structure on the performance of the catalyst was investigated by varying the atomic ratio of Cu^(0)/Cu^(+) on the catalyst surface,which resulted in improved ethylene selectivity.Under the optimal atomic ratio of Cu^(0)/Cu^(+),the charge transfer resistance was minimized,and the desorption rate of the intermediates was low,favoring C_(2) generation.Density functional theory calculations indicated that the Cu^(0)/Cu^(+) interfaces exhibited a lower Gibbs free energy for the rate-determining step,enhancing C_(2)H_(4) formation.The Cu/Cu_(2)O catalyst also exhibited a low Cu d-band center,which enhanced the adsorption stability of *CO on the surface and facilitated C_(2)formation.This observa-tion explained the higher yield of C_(2) products at the Cu^(0)/Cu^(+) interface than that of H_(2) under rapid mass transfer.The results of the net present value model showed that the H-cell holds promising industrial prospects,contingent upon it being a catalyst with both high selectivity and high current density.This approach of integrating the structure and composition provides new insights for ad-vancing the CO_(2)RR towards high-current C_(2) products.
基金supported by the National Natural Science Foundation of China (51372137)the National High Technology Research and Development Program of China (863 Program,2015AA034603)~~
文摘V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.
基金Supported by Fundamental Research Funds for Central Universities(HEUCF201403002)Advanced Technique Project Funds of the Manufacture and Information Ministry
文摘将厌氧发酵残留物作为肥料还田是其资源化利用的有效途径，但国内外对其还田后氨气（NH3）和氧化亚氮（N2O）的排放特征及氮素利用率的报道较少。本研究通过微区试验，探讨了冬季和夏季大棚菜地追施猪粪沼液（DPS）后NH3和N2O的排放速率及氮素损失率。结果发现， 追施DPS后菜地NH3挥发激增，通常发生在施肥后的48 h 内；而N2O排放量在第一次施肥后大幅增加，随后逐步趋于稳定。追施DPS的处理其NH3和N2O的排放量均显著高于施用化肥的处理，冬季和夏季二者的损失量分别占肥料总量的16.4%～23.2%和24.7%～27.5%。土壤温度、水分和pH对沼液中氮素以NH3和N2O的形式损失的影响较大。
