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Morphology and valence state evolution of Cu:Unraveling the impact on nitric oxide electroreduction

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Journal of Energy Chemistry 2024年第4期91卷 276-286页

作者： Ting Sun Fengyu Gao Ya Wang Honghong Yi Qingjun Yu shunzheng zhao Xiaolong Tang School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China

Ammonia(NH3)serves as a critical component in the fertilizer industry and fume gas denitrification.However,the conventional NH3production process,namely the Haber-Bosch process,leads to considerable energy consumption and waste gas emissions.To address this,electrocatalytic nitric oxide reduction reaction(NORR)has emerged as a promising strategy to bridge NH3consumption to NH3production,harnessing renewable electricity for a sustainable future.Copper(Cu)stands out as a prominent electrocatalyst for NO reduction,given its exceptional NH3yield and selectivity.However,a crucial aspect that remains insufficiently explored is the effects of morphology and valence states of Cu on the NORR performance.In this investigation,we synthesized CuO nanowires(CuO-NF)and Cu nanocubes(Cu-NF)as cathodes through an in situ growth method.Remarkably,CuO-NF exhibited an impressive NH3yield of 0.50±0.02 mg cm^(-2)h^(-1)at-0.6 V vs.reversible hydrogen electrode(RHE)with faradaic efficiency of29,68%±1,35%,surpassing that of Cu-NF(0.17±0.01 mg cm^(-2)h^(-1),16.18%±1.40%).Throughout the electroreduction process,secondary cubes were generated on the CuO-NF surface,preserving their nanosheet cluster morphology,sustained by an abundant supply of subsurface oxygen(s-O)even after an extended duration of 10 h,until s-O depletion ensued.Conversely,Cu-NF exhibited inadequate s-O content,leading to rapid crystal collapse within the same timeframe.The distinctive current-potential relationship,akin to a volcano-type curve,was attributed to distinct NO hydrogenation mechanisms.Further Tafel analysis revealed the exchange current density(i0)and standard heterogeneous rate constant(k0)for CuO-NF,yielding 3.44×10^(-6)A cm^(-2)and 3.77×10^(-6)cm^(-2)s^(-1)when NORR was driven by overpotentials.These findings revealed the potential of CuO-NF for NO reduction and provided insights into the intricate interplay between crystal morphology,valence states,and electrochemical performance.

关键词： NORR Ammonia Synthesis Copper Morphology Valence States Mechanism

Study on mechanism of low-temperature oxidation of n-hexanal catalysed by 2D ultrathin Co_(3)O_(4) nanosheets

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Nano Research 2022年第2期15卷 1660-1671页

作者： Leilei Miao Xiaolong Tang shunzheng zhao Xizhou Xie Chengcheng Du Tian Tang Honghong Yi Department of Environmental Enginnering School of Energy and Environmental EngineeringUniversity of Science and TechnologyBeijingBeijing 100083China Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants Beijing 100083China

Achieving high catalytic performance with lower possible cost and higher energetic efficiency is critical for catalytic oxidation of volatile organic compounds(VOCs).However,traditional thermocatalysts generally undergo low catalytic activity and fewer active sites.Herein,this paper synthesizes nearly all-surface-atomic,ultrathin two-dimensional(2D)Co_(3)O_(4) nanosheets to address these problems through offering a numerous active sites and high electron mobility.The 2D Co_(3)O_(4) nanosheets(1.70 nm)exhibit catalyzation to the total oxidation of n-hexanal at the lower temperature of r90%=202℃,and at the space velocity of 5.0×10^(4) h^(-1).It is over 1.2 and 6 times higher catalytic activity than that of 2D CoO nanosheets(1.71 nm)and bulk Co_(3)O_(4) counterpart,respectively.Transient absorption spectroscopy analysis shows that the oxygen vacancy defect traps electrons,thereby preventing the recombination with holes,increasing the lifetime of electrons,and making electron-holes reach a nondynamic equilibrium.The longer the electron lifetime is,the easier the oxygen vacancy defects capture electrons.Furthermore,the defects combine with oxygen to form active oxygen components.Compared with the lattice oxygen involved in the reaction of bulk Co_(3)O_(4),the nanosheets change the catalytic reaction path,which effectively reduces the activation energy barrier from 34.07 to 27.15 kJ/mol.The changed surface disorder,the numerous coordinatively-unsaturated Co atoms and the high ratio of O_(ads)/O_(lat) on the surface of 2D Co_(3)O_(4) nanosheets are responsible for the catalytic performance.

关键词： catalytic reaction n-hexanal oxidation two-dimensional nanosheets oxygen vacancy defect coordinated unsaturated atom

δ-MnO_(2) decorated layered double oxides in-situ grown on nickel foam towards electrothermal catalysis of n-heptane

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Journal of Environmental Sciences 2023年第4期126卷 308-320页

作者： Chaoqi Chen shunzheng zhao Xiaolong Tang Honghong Yi Fengyu Gao Qingjun Yu Jun Liu Weixiao Wang Tian Tang Xianzheng Meng Department of Environmental Engineering School of Energy and Environmental EngineeringUniversity of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants Beijing 100083China

Energy-saving and efficient monolithic catalysts are hotspots of catalytic purification of industrial gaseous pollutants.Here,we have developed an electrothermal catalytic mode,in which the ignition temperature required for the reaction is provided by Joule heat generated when the current flows through the catalyst.In this paper,Mn/NiAl/NF,Mn/NiFe/NF and Mn/NF metal-based monolithic catalysts were prepared using nickel foam (NF) as the carrier for thermal and electrothermal catalysis of n-heptane.The results indicated that Mn-based monolithic catalysts exhibit high activity in thermal and electrothermal catalysis.Mn/NiFe/NF achieve conversion of n-heptane more than 99%in electrothermal catalysis under a direct-current (DC) power of 6 W,and energy-saving is 54% compared with thermal catalysis.In addition,the results indicated that the introduction of NiAl (or NiFe) greatly enhanced the catalytic activity of Mn/NF,which attributed to the higher specific surface area,Mn3+/Mn4+,Ni3+/Ni^(2+),adsorbed oxygen species (Oads)/lattice oxygen species (Olatt),redox performance of the catalyst.Electrothermal catalytic activity was significantly higher than thermal catalytic activity before complete conversion,which may be related to electronic effects.Besides,Mn/NiFe/NF has good cyclic and long-term stability in electrothermal catalysis.This paper provided a theoretical basis for applying electrothermal catalysis in the field of VOCs elimination.

关键词： Monolithic catalyst MnO_(2) Electric heating n-Heptane

Mn2NiO4 spinel catalyst for high-efficiency selective catalytic reduction of nitrogen oxides with good resistance to H2O and SO2 at low temperature

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Journal of Environmental Sciences 2020年第3期32卷 145-155页

作者： Fengyu Gao Xiaolong Tang Honghong Yi shunzheng zhao Wenjuan Zhu Yiran Shi School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Resource-Oriented Treatment of Industrial Pollutants University of Science and Technology BeijingBeijing 100083China

Mn-Ni oxides with different compositions were prepared using standard co-precipitation(CP) and urea hydrolysis-precipitation(UH) methods and optimized for the selective catalytic reduction of nitrogen oxides(NOx) by NH3 at low temperature.Mn((2))Ni(1)Ox-CP and Mn(2)Ni(1)Ox-UH(with Mn:Ni molar ratio of 2:1) catalysts showed almost identical selective catalytic reduction(SCR) catalytic activity,with about 96% NOx conversion at 750 C and-99%in the temperature range from 100 to 250℃.X-ray diffraction(XRD) results showed that Mn(2)Ni(1)Ox-CP and Mn(2)Ni(1)Ox-UH catalysts crystallized in the form of Mn2NiO4 and MnO2-Mn2NiO4 spinel,respectively.The latter gave relatively good selectivity to N2,which might be due to the presence of the MnO2 phase and high metal-O binding energy,resulting in low dehydrogenation ability.According to the results of various characterization methods,it was found that a high density of surface chemisorbed oxygen species and efficient electron transfer between Mn and Ni in the crystal structure of Mn2NiO4 spinel played important roles in the high-efficiency SCR activity of these catalysts.Mn(2)Ni(1)Ox catalysts presented good resistance to H2O or/and SO2 with stable activity,which benefited from the Mn2NiO4 spinel structure and Eley-Rideal mechanism,with only slight effects from SO2.

关键词： Mn-Ni oxides Spinel structure Low-temperature SCR H2O and SO2 resistance Eley-Rideal mechanism

Simultaneous removal of gaseous CO and elemental mercury over Cu-Co modified activated coke at low temperature

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Journal of Environmental Sciences 2021年第3期33卷 36-48页

作者： Fengyu Gao Hao Yan Xiaolong Tang Honghong Yi shunzheng zhao Qingjun Yu Shuquan Ni School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants University of Science and Technology BeijingBeijing 100083China

Cu-Co multiple-oxides modified on HNO_3-pretreated activated coke(AC_(N))were optimized for the simultaneous removal of gaseous CO and elemental mercury(Hg^(0))at low temperature(<200℃).It was found that 2%CuOx-10%CoOx/AC_(N)catalyst calcined at 400℃resulted in the coexistence of complex oxides including CuO,Cu_2 O,Co_(3)O_(4,Co_(2)O_(3)and CoO phases,which might be good for the simultaneous catalytic oxidation of CO by Co-species and removal of Hg^(0)by Cu-species,benefiting from the synergistic catalysis during the electrointeraction between Go and Cu cations(CoO■Co_(3)O_(4)and Cu_(2)O■CuO).The catalysis removal of CO oxidation was obviously depended on the reaction temperature obtaining94.7%at 200℃,while no obvious promoting effect on the Hg^(0)removal(68.3%-78.7%).These materials were very substitute for the removal of CO and Hg^(0)from the flue gas with the conditions of 8-20 vol.%O_(2)and flue-gas temperature below 200℃.The removal of Hg^(0)followed the combination processes of adsorption and catalytic oxidation reaction via LangmuirHinshelwood mechanism,while the catalysis of CO abided by the Mars-van Krevelen mechanism with lattice oxygen species.

关键词： Synergetic catalysis Cu-Co oxides Carbon monoxide Element mercury Activated coke

Behaviors and kinetics of toluene adsorption-desorption on activated carbons with varying pore structure

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Journal of Environmental Sciences 2018年第5期30卷 104-114页

作者： Xi Yang Honghong Yi Xiaolong Tang shunzheng zhao Zhongyu Yang Yueqiang Ma Tiecheng Feng Xiaoxu Cui School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Resource-oriented Treatment of industrial Pollutants Beijing 100083China

This work was undertaken to investigate the behaviors and kinetics of toluene adsorption and desorption on activated carbons with varying pore structure. Five kinds of activated carbon from different raw materials were selected. Adsorption isotherms and breakthrough curves for toluene were measured. Langmuir and Freundlich equations were fitted to the equilibrium data, and the Freundlich equation was more suitable for simulating toluene adsorption. The process consisted of monolayer, multilayer and partial active site adsorption types. The effect of the pore structure of the activated carbons on toluene adsorption capacity was investigated. The quasi-first-order model was more suitable for describing the process than the quasi-second-order model. The adsorption data was also modeled by the internal particle diffusion model and it was found that the adsorption process could be divided into three stages. In the external surface adsorption process, the rate depended on the specific surface area. During the particle diffusion stage, pore structure and volume were the main factors affecting adsorption rate. In the final equilibrium stage, the rate was determined by the ratio of meso-and macro-pores to total pore volume. The rate over the whole adsorption process was dominated by the toluene concentration. The desorption behavior of toluene on activated carbons was investigated,and the process was divided into heat and mass transfer parts corresponding to emission and diffusion mechanisms, respectively. Physical adsorption played the main role during the adsorption process.

关键词： Activated carbon Toluene Adsorption Desorption Kinetics

The poisoning and regeneration effect of alkali metals deposed over commercial V_2O_5-WO_3/TiO_2 catalysts on SCR of NO by NH_3

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Chinese Science Bulletin 2014年第26期59卷 3966-3972页

作者： Fengyu Gao Xiaolong Tang Honghong Yi shunzheng zhao Tongtong Zhang Dong Li Ding Ma Department of Environmental Engineering Civil and Environmental Engineering SchoolUniversity of Science and Technology Beijing

In this study,commercial V2O5-WO3/TiO2catalysts were deactivated by loading with alkali metals(K and Na).These catalysts were then regenerated by washing with either deionized water or 0.5 mol/L H2SO4(through the ultrasonic-assisted method).The samples used in this research were characterized by NH3-temperature programmed desorption(TPD),and X-ray photoelectron spectroscopy(XPS).Results showed that Na2O and K2O doping can poison the V2O5-WO3/TiO2catalyst and that the poisoning effect of Na2O was stronger than that of K2O.However,the Na2O-loaded sample was easier to regenerate than the K2O-loaded sample.The surfaces of catalysts can be sulfated by washing with dilute sulfuric acid because strong acid sites adhere to the catalyst surface.SO42-could also promote catalyst activity.As indicated by the NH3-TPD findings,the deposition of Na2O and K2O could also reduce the amount of desorbed ammonia and destabilize the acid sites,especially strong chemisorption sites.XPS results revealed that catalysts were deactivated by the decrease in the concentration of chemisorbed oxygen[the Oa/(Oα+Oβ)ratio].In the Na2O-doped catalyst,much chemisorbed oxygen was lost(from 28.8%to10.6%).However,the decrease in the Oa/(Oα+Oβ)ratio was less significant in the K2O-doped catalyst(from28.8%to 23.5%).Nonetheless,the binding energies of O1s broadened with respect to both high and low energy.In particular,the binding energy of chemisorbed oxygen increased from 531.5 to 531.8 eV.

关键词： TiO2催化剂 NH3-TPD 再生效果碱金属商业 SCR X射线光电子能谱催化剂表面

Formation of active oxygen species on single-atom Pt catalyst and promoted catalytic oxidation of toluene

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Nano Research 2020年第6期13卷 1544-1551页

作者： shunzheng zhao Yanfeng Wen Xijun Liu Xianyun Pen Fang Lü Fengyu Gao Xizhou Xie Chengcheng Du Honghong Yi Dongjuan Kang Xiaolong Tang Department of Environmental Engineering University of Science and Technology BeijingBeijing100083China Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants Beijing100083China Center for Electron Microscopy and Tianjin Key Lab of Advanced Functional Porous Materials Institute for New Energy Materials&Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin300384China

Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds(VOCs).However,to fully understand the activation of molecular oxygen and the role of active oxygen species generated in this reaction is still a challenging target.Herein,MgO nanosheets and single-atom Pt loaded MgO(Pt SA/MgO)nanosheets were synthesized and used as catalysts in toluene oxidation.The activation process of molecular oxygen and oxidation performance on the two catalysts were contrastively investigated.The Pt SA/MgO exhibited significantly enhanced catalytic activity compared to MgO.The oxygen vacancies can be easily generated on the Pt SA/MgO surface,which facilitate the activation of molecular oxygen and the formation of active oxygen species.Based on the experimental data and theoretical calculations,an active oxygen species promoted oxidation mechanism for toluene was proposed.In the presence of H2O,the molecular oxygen is more favorable to be dissociated to generate•OH on the oxygen vacancies of the Pt SA/MgO surface,which is the dominant active oxygen species.We anticipate that this work may shed light on further investigation of t10.1007/s12274-020-2765-1he oxidation mechanism of toluene and other VOCs over noble metal catalysts.

关键词： single-atom Pt activation of molecular oxygen oxygen vacancies active oxygen species oxidation of toluene

新型多孔三聚氰胺负载MnCe用于高选择性电催化CO_(2)产甲酸

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化学学报 2024年第4期82卷 396-408页

作者：雷雅茹熊廷楷于湘涛黄秀兵唐晓龙易红宏周远松赵顺征孙龙高凤雨北京科技大学能源与环境工程学院工业典型污染物资源化处理北京市重点实验室北京100083 北京科技大学钢铁共性技术协同创新中心北京100083 北京科技大学材料科学与工程学院北京100083

本研究提出了一种尚未见报道的CO_(2)还原电催化剂及其构造,由MnCe作为活性位点,三聚氰胺泡沫(MS)作为载体前驱体的新型电极材料——MnCe-CMS(碳化MS)和MnCe-GOMS(氧化石墨烯活化MS),用于电催化CO_(2)还原研究.结果发现,MnCe-MS具有较... 详细信息

本研究提出了一种尚未见报道的CO_(2)还原电催化剂及其构造,由MnCe作为活性位点,三聚氰胺泡沫(MS)作为载体前驱体的新型电极材料——MnCe-CMS(碳化MS)和MnCe-GOMS(氧化石墨烯活化MS),用于电催化CO_(2)还原研究.结果发现,MnCe-MS具有较宽的电位范围(-0.2~-3 V vs.RHE)及较好的产甲酸能力.对比以常用的碳布(CC)为载体的MnCe-CC,MnCe-CMS和MnCe-GOMS的甲酸生成速率分别提高到2.3、2.8倍,法拉第效率分别提高到2.3、2.5倍(MnCe-CC的最佳电位-0.4 V条件下),并且MnCe-GOMS在-0.6 V表现出最佳甲酸法拉第效率(75.72%).这归因于MS材料丰富的孔隙结构、较大的电化学表面积、易形成碳缺陷的特点,分析表明GO的掺入可以进一步增大这些优势;此外,在Mn、Ce共同作用下,有效促进电子传输、抑制析氢竞争反应、形成氧空位,有利于CO_(2)的吸附、活化与转化,从而促进甲酸生成.

关键词：电催化CO_(2)还原技术甲酸 Mn Ce 三聚氰胺泡沫(MS) 氧化石墨烯活化高温碳化