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
过氧化氢(H_(2)O_(2))是一种重要的化工产品,广泛应用于污水处理、消毒杀菌和印染漂白等领域.在蒽醌法生产H_(2)O_(2)的过程中,易产生有毒气体并存在爆炸危险.因此,仅利用水、氧气和太阳光即可在合适的光催化剂上生成H_(2)O_(2)的光催...过氧化氢(H_(2)O_(2))是一种重要的化工产品,广泛应用于污水处理、消毒杀菌和印染漂白等领域.在蒽醌法生产H_(2)O_(2)的过程中,易产生有毒气体并存在爆炸危险.因此,仅利用水、氧气和太阳光即可在合适的光催化剂上生成H_(2)O_(2)的光催化技术备受关注.本课题组报道了通过酸碱自组装法制备的四(4-羧基苯基)卟啉(SA-TCPP)光催化剂,用于生产H_(2)O_(2).该催化剂克服了大部分H_(2)O_(2)光催化剂存在的需要牺牲剂、活性低和光利用率不足等问题,但其性能仍受限于较高的复合率.晶面调控已被证实是改善许多无机催化剂电荷复合的有效策略,然而,对于有机光催化剂,关于暴露晶面与其活性关系的研究仍然较少.本文采用溶解-重结晶法在水和三种有机溶剂的混合物中成功合成了三种具有不同暴露晶面的卟啉光催化剂.即利用卟啉在有机溶剂和水中的溶解度差异,将卟啉先溶解在四氢呋喃(THF)、甲醇(MeOH)或乙二醇(EG)溶液中,随后在水溶液中重新结晶.X射线衍射、高分辨率透射电子显微镜及晶面模拟模型图的结果表明,三种催化剂具有相同的晶体结构,但分别暴露了(400)、(022)和(020)晶面.通过紫外分光光度计测量这些催化剂在氙灯(λ≥420 nm)照射下的光催化活性,结果表明,具有(400)暴露面的卟啉光催化剂的H_(2)O_(2)生产速率最高,可达29.33 mmol L h^(-1)g^(-1),分别是具有(022)暴露面和(020)暴露面的卟啉光催化剂的2.7倍和4.1倍,约是已报道的SA-TCPP光催化剂的1.3倍.通过紫外漫反射、莫特肖特基曲线分析以及LED灯照射下的光催化活性测试,排除了光吸收能力对这三种卟啉光催化剂活性的影响.开尔文探针力显微镜、光生电流密度谱图、晶面模拟模型图和密度泛函理论计算结果表明,活性的差异主要归因于(400)表面暴露的高羧基含量所引发的强内建电场,并且在该暴露面上的内建电场方向有利于空穴从吡咯氮向羧基碳的跃迁,因此阻碍了电荷的快速重组,促进了富有挑战性的水氧化过程,而(020)面由于暴露了最多的吡咯氮和最少的羧基碳,其产生的内建电场强度最弱,且内建电场方向阻碍了空穴向羧基碳的跃迁,因此H_(2)O_(2)生产速率最低.综上所述,本工作通过晶面调控产生强内建电场以加速空穴的迁移,降低了电子空穴复合速率,实现了高H_(2)O_(2)生产速率,为更高效的有机光催化剂的设计和开发提供了新思路.展开更多
制备了负载在Na Y分子筛上的Fe Cu Mn Y复合催化剂,并对其在非均相UV Fe Cu Mn Y H2O2体系中催化氧化4BS染料废水进行了研究.结果表明,非均相UV Fe Cu Mn Y H2O2体系对4BS染料废水的处理具有很高的效率.在基准条件下,反应时间为20min时...制备了负载在Na Y分子筛上的Fe Cu Mn Y复合催化剂,并对其在非均相UV Fe Cu Mn Y H2O2体系中催化氧化4BS染料废水进行了研究.结果表明,非均相UV Fe Cu Mn Y H2O2体系对4BS染料废水的处理具有很高的效率.在基准条件下,反应时间为20min时,废水中4BS的去除率达到了93 7%.与均相UV Fenton体系不同,非均相UV Fe Cu Mn Y H2O2体系在碱性条件下(pH=10 5)仍可高效去除CODCr.动力学研究得到催化氧化4BS废水的模型方程,该模型可以为非均相UV Fe Cu Mn Y H2O2体系处理高色度的实际染料废水提供指导.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.
文摘过氧化氢(H_(2)O_(2))是一种重要的化工产品,广泛应用于污水处理、消毒杀菌和印染漂白等领域.在蒽醌法生产H_(2)O_(2)的过程中,易产生有毒气体并存在爆炸危险.因此,仅利用水、氧气和太阳光即可在合适的光催化剂上生成H_(2)O_(2)的光催化技术备受关注.本课题组报道了通过酸碱自组装法制备的四(4-羧基苯基)卟啉(SA-TCPP)光催化剂,用于生产H_(2)O_(2).该催化剂克服了大部分H_(2)O_(2)光催化剂存在的需要牺牲剂、活性低和光利用率不足等问题,但其性能仍受限于较高的复合率.晶面调控已被证实是改善许多无机催化剂电荷复合的有效策略,然而,对于有机光催化剂,关于暴露晶面与其活性关系的研究仍然较少.本文采用溶解-重结晶法在水和三种有机溶剂的混合物中成功合成了三种具有不同暴露晶面的卟啉光催化剂.即利用卟啉在有机溶剂和水中的溶解度差异,将卟啉先溶解在四氢呋喃(THF)、甲醇(MeOH)或乙二醇(EG)溶液中,随后在水溶液中重新结晶.X射线衍射、高分辨率透射电子显微镜及晶面模拟模型图的结果表明,三种催化剂具有相同的晶体结构,但分别暴露了(400)、(022)和(020)晶面.通过紫外分光光度计测量这些催化剂在氙灯(λ≥420 nm)照射下的光催化活性,结果表明,具有(400)暴露面的卟啉光催化剂的H_(2)O_(2)生产速率最高,可达29.33 mmol L h^(-1)g^(-1),分别是具有(022)暴露面和(020)暴露面的卟啉光催化剂的2.7倍和4.1倍,约是已报道的SA-TCPP光催化剂的1.3倍.通过紫外漫反射、莫特肖特基曲线分析以及LED灯照射下的光催化活性测试,排除了光吸收能力对这三种卟啉光催化剂活性的影响.开尔文探针力显微镜、光生电流密度谱图、晶面模拟模型图和密度泛函理论计算结果表明,活性的差异主要归因于(400)表面暴露的高羧基含量所引发的强内建电场,并且在该暴露面上的内建电场方向有利于空穴从吡咯氮向羧基碳的跃迁,因此阻碍了电荷的快速重组,促进了富有挑战性的水氧化过程,而(020)面由于暴露了最多的吡咯氮和最少的羧基碳,其产生的内建电场强度最弱,且内建电场方向阻碍了空穴向羧基碳的跃迁,因此H_(2)O_(2)生产速率最低.综上所述,本工作通过晶面调控产生强内建电场以加速空穴的迁移,降低了电子空穴复合速率,实现了高H_(2)O_(2)生产速率,为更高效的有机光催化剂的设计和开发提供了新思路.
文摘制备了负载在Na Y分子筛上的Fe Cu Mn Y复合催化剂,并对其在非均相UV Fe Cu Mn Y H2O2体系中催化氧化4BS染料废水进行了研究.结果表明,非均相UV Fe Cu Mn Y H2O2体系对4BS染料废水的处理具有很高的效率.在基准条件下,反应时间为20min时,废水中4BS的去除率达到了93 7%.与均相UV Fenton体系不同,非均相UV Fe Cu Mn Y H2O2体系在碱性条件下(pH=10 5)仍可高效去除CODCr.动力学研究得到催化氧化4BS废水的模型方程,该模型可以为非均相UV Fe Cu Mn Y H2O2体系处理高色度的实际染料废水提供指导.
