The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior...The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior （temperature-programmed reduction/temperatureprogrammed re-oxidation） as well as the catalytic properties of Co3O4 thin films. The syntheses of Co3O4 were achieved by chemical vapor deposition in the temperature range of 400-500℃. The structure analysis of the as-prepared material revealed the presence of two prominent IR bands peaking at 544 cm-1 （υ1） and 650 cm-1 （υ2） respectively, which originate from the stretching vibrations of the Co-O bond, characteristic of the Co3O4 spinel. The lattice stability limit of Co3O4 was estimated to be above 650℃. The redox properties of the spinel structure were determined by integrating the area under the emission bands υ1 and υ2 as a function of the temperature. Moreover, Co3O4 has been successfully tested as a catalyst towards complete oxidation of dimethyl ether below 340 ℃. The exhaust gas analysis during the catalytic process by in situ absorption FTIR revealed that only CO2 and H2O were detected as the final products in the catalytic reaction. The redox behavior suggests that the oxidation of dimethyl ether over Co3O4 follows a Mars-van Krevelen type mechanism. The comprehensive application of in situ FTIR provides a novel diagnostic tool in characterization and performance test of catalysts.展开更多
The active sites for hydrogenation over Ru/SBA‐15catalysts were identified using in situ Fourier‐transform infrared spectroscopy.The amount of active sites was proportional to the interfacial circumference of the Ru...The active sites for hydrogenation over Ru/SBA‐15catalysts were identified using in situ Fourier‐transform infrared spectroscopy.The amount of active sites was proportional to the interfacial circumference of the Ru particles.In contrast,the rate of hydrogen spillover from Ru to the support was inversely proportional to the size of the Ru metal particles.Consequently,a catalyst with small Ru metal particles has a high rate of hydrogen spillover but a low density of active sites,whereas one with large Ru particles has a low rate of hydrogen spillover but a high density of active sites.The formation of these active sites is probably an intermediate step in hydrogen spillover.展开更多
为实现光谱技术对麦麸固体发酵过程中不同成分变化的在线监测,通过国家标准方法测定61份麦麸固体发酵饲料样本的蛋白质、水分、总酚和粗纤维含量,采集样本近红外光谱(NIR)和傅里叶变换红外光谱(FT-IR),经过标准正态变换(standard normal...为实现光谱技术对麦麸固体发酵过程中不同成分变化的在线监测,通过国家标准方法测定61份麦麸固体发酵饲料样本的蛋白质、水分、总酚和粗纤维含量,采集样本近红外光谱(NIR)和傅里叶变换红外光谱(FT-IR),经过标准正态变换(standard normal variate transformation,SNV)、多元散射校正(multiplicative scatter correction,MSC)、平滑(smoothing)等9种预处理方法对原始光谱进行校正,结合偏最小二乘法(partial least squares,PLS)建立4种成分的NIR和FT-IR定量分析模型并进行比较分析。结果表明:所建立的4种成分NIR和FT-IR模型的训练集决定系数(Rc^(2))和验证集决定系数(Rp^(2))均大于0.8,交叉验证均方根误差(root mean square error of cross validation,RMSECV)小于2.0,训练集均方根误差(root mean square error of calibration,RMSEC)和验证集均方根误差(root mean square error of prediction,RMSEP)小于1.0。因此,所建立的NIR和FT-IR定量分析模型具有较好的准确性和稳定性,能够对麦麸固体发酵过程中不同成分变化实行快速监测。展开更多
In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was p...In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was prepared by the calcination method and investigated for the CO oxidation. The microstructure and morphology of CeO2-Co3O4 were investigated by the Scanning Electron Microscope, High-resolution transmission electron microscopy, Raman and X-ray photoelectron spectroscopy characterization. The effect of CeO2 doping on Co3O4 for CO oxidation was characterized by in situ X-ray Diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). In situ XRD was carried out under H2 atmosphere to evaluate the redox property of catalysts. The results indicated that the ceria doping can enhance the reducibility of Co2+ and promote the Co3+-Co2+-Co3+ cycle, owing to the oxygen replenish property of CeO2. Furthermore, adsorbed carbonate species on the surface of CeO2-Co3O4 were investigated by in situ-DRIFTS experiment. It was turned out that carbonate species on ceria promoted cobalt oxide catalysts showed different IR peaks compared with pure cobalt oxide. The carbonate species on ceria promoted catalyst are more active, and similar to free state carbonate species with weak bonding to catalyst surface, which can effectively inhibit catalyst inactivation. This study revealed the mechanism of ceria promoting CO oxidation over cobalt oxide, which will provide theoretical support for the design of efficient CO oxidation catalysts.展开更多
Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2w...Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.展开更多
As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in ...As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in energy calls for EECS devices with high efficiency and enhanced performance,which mainly rely on the rational design of catalysts,electrode materials,and electrode/electrolyte interfaces in EESC,based on in-deep and comprehensive mechanistic understanding of the relevant electrochemical redox reactions.Such an understanding can be realized by monitoring the dynamic redox reaction processes under realistic operation conditions using in situ techniques,such as in situ Raman,Fourier transform infrared(FTIR),and X-ray diffraction(XRD)spectroscopy.These techniques can provide characteristic spectroscopic information of molecules and/or crystals,which are sensitive to structure/phase changes resulted from different electrochemical working conditions,hence allowing for intermediates identification and mechanisms understanding.This review described and summarized recent progress in the in situ studies of fuel cells and rechargeable batteries via Raman,FTIR,and XRD spectroscopy.The applications of these in situ techniques on typical electrocatalytic electrooxidation reaction and oxygen reduction reaction(ORR)in fuel cells,on representative high capacity and/or resource abundance cathodes and anodes,and on the solid electrolyte interface(SEI)in rechargeable batteries are discussed.We discuss how these techniques promote the development of novel EECS systems and highlight their critical importance in future EECS research.展开更多
文摘The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior （temperature-programmed reduction/temperatureprogrammed re-oxidation） as well as the catalytic properties of Co3O4 thin films. The syntheses of Co3O4 were achieved by chemical vapor deposition in the temperature range of 400-500℃. The structure analysis of the as-prepared material revealed the presence of two prominent IR bands peaking at 544 cm-1 （υ1） and 650 cm-1 （υ2） respectively, which originate from the stretching vibrations of the Co-O bond, characteristic of the Co3O4 spinel. The lattice stability limit of Co3O4 was estimated to be above 650℃. The redox properties of the spinel structure were determined by integrating the area under the emission bands υ1 and υ2 as a function of the temperature. Moreover, Co3O4 has been successfully tested as a catalyst towards complete oxidation of dimethyl ether below 340 ℃. The exhaust gas analysis during the catalytic process by in situ absorption FTIR revealed that only CO2 and H2O were detected as the final products in the catalytic reaction. The redox behavior suggests that the oxidation of dimethyl ether over Co3O4 follows a Mars-van Krevelen type mechanism. The comprehensive application of in situ FTIR provides a novel diagnostic tool in characterization and performance test of catalysts.
基金supported by the National Natural Science Foundation of China(21303163)the Natural Science Foundation of Zhejiang Province(LY13B030006,LY17B060006)+1 种基金the Qianjiang Talent Project in Zhejiang Province(QJD1302011)the Scientific Research Fund of Zhejiang Provincial Education Department(Y201328681)~~
文摘The active sites for hydrogenation over Ru/SBA‐15catalysts were identified using in situ Fourier‐transform infrared spectroscopy.The amount of active sites was proportional to the interfacial circumference of the Ru particles.In contrast,the rate of hydrogen spillover from Ru to the support was inversely proportional to the size of the Ru metal particles.Consequently,a catalyst with small Ru metal particles has a high rate of hydrogen spillover but a low density of active sites,whereas one with large Ru particles has a low rate of hydrogen spillover but a high density of active sites.The formation of these active sites is probably an intermediate step in hydrogen spillover.
文摘为实现光谱技术对麦麸固体发酵过程中不同成分变化的在线监测,通过国家标准方法测定61份麦麸固体发酵饲料样本的蛋白质、水分、总酚和粗纤维含量,采集样本近红外光谱(NIR)和傅里叶变换红外光谱(FT-IR),经过标准正态变换(standard normal variate transformation,SNV)、多元散射校正(multiplicative scatter correction,MSC)、平滑(smoothing)等9种预处理方法对原始光谱进行校正,结合偏最小二乘法(partial least squares,PLS)建立4种成分的NIR和FT-IR定量分析模型并进行比较分析。结果表明:所建立的4种成分NIR和FT-IR模型的训练集决定系数(Rc^(2))和验证集决定系数(Rp^(2))均大于0.8,交叉验证均方根误差(root mean square error of cross validation,RMSECV)小于2.0,训练集均方根误差(root mean square error of calibration,RMSEC)和验证集均方根误差(root mean square error of prediction,RMSEP)小于1.0。因此,所建立的NIR和FT-IR定量分析模型具有较好的准确性和稳定性,能够对麦麸固体发酵过程中不同成分变化实行快速监测。
基金supported by the State Key Research Development Program of China(2016YFA0204200)the National Natural Science Foundation of China(21822603,21577036,21773062)+3 种基金the Shanghai Pujiang Program(17PJD011)the Zhejiang public welfare technology research plan/rural agriculture(LGN18B010001)the Zhejiang provincial Collaborative Innovation Center of Agricultural Biological Resources Biochemical Manufacturing(NO:2016KF0005)the scientific research project of Zhejiang provincial education department(Y201839892)~~
文摘In situ studies of catalysts play valuable roles in observing phase transformation, understanding the corresponding surface chemistry and the mechanism of the reaction. In this paper, ceria promoted cobalt oxide was prepared by the calcination method and investigated for the CO oxidation. The microstructure and morphology of CeO2-Co3O4 were investigated by the Scanning Electron Microscope, High-resolution transmission electron microscopy, Raman and X-ray photoelectron spectroscopy characterization. The effect of CeO2 doping on Co3O4 for CO oxidation was characterized by in situ X-ray Diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). In situ XRD was carried out under H2 atmosphere to evaluate the redox property of catalysts. The results indicated that the ceria doping can enhance the reducibility of Co2+ and promote the Co3+-Co2+-Co3+ cycle, owing to the oxygen replenish property of CeO2. Furthermore, adsorbed carbonate species on the surface of CeO2-Co3O4 were investigated by in situ-DRIFTS experiment. It was turned out that carbonate species on ceria promoted cobalt oxide catalysts showed different IR peaks compared with pure cobalt oxide. The carbonate species on ceria promoted catalyst are more active, and similar to free state carbonate species with weak bonding to catalyst surface, which can effectively inhibit catalyst inactivation. This study revealed the mechanism of ceria promoting CO oxidation over cobalt oxide, which will provide theoretical support for the design of efficient CO oxidation catalysts.
基金supported by the National Natural Science Foundation of China(51708078,21576034)Chongqing Postdoctoral Science Foundation funded project(Xm2016027)the Innovative Research Team of Chongqing(CXTDG201602014,CXTDX201601016)~~
文摘Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.
基金supported by the National Key Research and Development Program of China(Nos.2020YFB1505800 and 2019YFA0705400)the National Natural Science Foundation of China(NSFC)(Nos.201925404,21902137,22005130,and 22021001)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.20720210069 and 20720210043)the Science and Technology Planning Project of Fujian Province(No.2019Y4001).
文摘As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in energy calls for EECS devices with high efficiency and enhanced performance,which mainly rely on the rational design of catalysts,electrode materials,and electrode/electrolyte interfaces in EESC,based on in-deep and comprehensive mechanistic understanding of the relevant electrochemical redox reactions.Such an understanding can be realized by monitoring the dynamic redox reaction processes under realistic operation conditions using in situ techniques,such as in situ Raman,Fourier transform infrared(FTIR),and X-ray diffraction(XRD)spectroscopy.These techniques can provide characteristic spectroscopic information of molecules and/or crystals,which are sensitive to structure/phase changes resulted from different electrochemical working conditions,hence allowing for intermediates identification and mechanisms understanding.This review described and summarized recent progress in the in situ studies of fuel cells and rechargeable batteries via Raman,FTIR,and XRD spectroscopy.The applications of these in situ techniques on typical electrocatalytic electrooxidation reaction and oxygen reduction reaction(ORR)in fuel cells,on representative high capacity and/or resource abundance cathodes and anodes,and on the solid electrolyte interface(SEI)in rechargeable batteries are discussed.We discuss how these techniques promote the development of novel EECS systems and highlight their critical importance in future EECS research.
基金supported by the National Natural Science Foundation of China (51176118,51306115)the China Postdoctoral Science Foundation (2012M520894,2013T60445)~~
