The transparent C-doped TiO2 nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method.The as-prepared films were characterized by X-ray diffraction(XRD),scanning electron m...The transparent C-doped TiO2 nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method.The as-prepared films were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),UV-visible absorption spectra(UV-vis)and X-ray photoelectron spectroscopy(XPS).The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature.The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping.The calcination temperatures significantly affect the morphology,microstructure and photocatalytic activity of the as-prepared samples.At 723 K,the C-doped TiO2 films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization,appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.展开更多
We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5(C-GST) films during heating in air. Both the C-GST films without and with a thin SiO2...We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5(C-GST) films during heating in air. Both the C-GST films without and with a thin SiO2 capping layer(C-GST and C-GST/SiO2) are deposited for comparison. Large differences are observed between C-GST and C-GST/SiO2 films in resistance-temperature, x-ray diffraction, x-ray photoelectron spectroscopy,Raman spectra, data retention capability and optical band gap measurements. In the C-GST film, resistancetemperature measurement reveals an unusual smooth decrease in resistance above 110℃ during heating. Xray diffraction result has excluded the possibility of phase change in the C-GST film below 170℃. The x-ray photoelectron spectroscopy experimental result reveals the evolution of Te chemical valence because of the carbon oxidation during heating. Raman spectra further demonstrate that phase changes from an amorphous state to the hexagonal state occur directly during heating in the C-GST film. The quite smooth decrease in resistance is believed to be related with the formation of Te-rich GeTe4-n Gen(n = 0, 1) units above 110℃ in the C-GST film. The oxidation of carbon is harmful to the C-GST phase change properties.展开更多
To achieve efficient photocatalytic H2 generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reporte...To achieve efficient photocatalytic H2 generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H2 generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H2 under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H2 generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(ND)in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.展开更多
Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolu...Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolution reaction(HER)by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H*desorption.Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8-0.4 nm NPs present on TNT layers,and it emerges with the highest HER activity among all the electrodes synthesized.A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti3+states and the coexistence of Ru SAs and NPs.With insights from literature,the role of Ti3+,appropriate work functions of TNT layers and Ru,and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified.The aforementioned characteristics led to a remarkable performance by having 9mV onset potentials and 33 mV dec-1 of Tafel slopes and a higher turnover frequency of 1.72 H2 s-1 at 30 mV.Besides,a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.展开更多
利用太阳能等可再生能源已经成为解决环境和能源问题的重要研究方向。本文通过经典的模板法制备中空TiO2,考察其光催化降解罗丹明B (RhB)的活性,并通过SEM、TEM、XRD、UV-Vis等手段分析中空TiO2的形貌与结构、光电化学性能以及光催化降...利用太阳能等可再生能源已经成为解决环境和能源问题的重要研究方向。本文通过经典的模板法制备中空TiO2,考察其光催化降解罗丹明B (RhB)的活性,并通过SEM、TEM、XRD、UV-Vis等手段分析中空TiO2的形貌与结构、光电化学性能以及光催化降解机理。结果表明,在模拟太阳光照射300 min后,中空TiO2对RhB的降解率高达94.4%,降解动力学常数(k)可达0.0066 min−1,是普通TiO2的9倍。本工作可为光催化降解有机污染物提供新的思路。The utilization of renewable energy such as solar energy has become an important research direction in solving environmental and energy problems. This paper uses a classic template method to prepare hollow TiO2 and investigate its photocatalytic degradation performance of RhB. The morphology, structure, photo-electrochemical and photocatalytic degradation mechanism of hollow TiO2 is analyzed by means of SEM, TEM, XRD, UV-Vis, etc. These results indicate that after simulating solar irradiation for 300 minutes, the degradation rate of RhB by hollow TiO2 was as high as 94.4%, and the degradation kinetics constant (k) of RhB by hollow TiO2 can reach 0.0066 min-1, which is 9 times higher than that of ordinary TiO2. This work can provide new ideas for photocatalytic degradation of organic pollutants.展开更多
本文采用水热法合成了具有不同吸光度的碳点(CDs),研究CDs吸光度对CDs/TiO2纳米复合材料光催化活性的影响。利用透射电子显微镜、傅里叶变换红外光谱仪、X射线光电子能谱仪对CDs/TiO2纳米复合材料的结构、形貌和化学组成进行了表征,并...本文采用水热法合成了具有不同吸光度的碳点(CDs),研究CDs吸光度对CDs/TiO2纳米复合材料光催化活性的影响。利用透射电子显微镜、傅里叶变换红外光谱仪、X射线光电子能谱仪对CDs/TiO2纳米复合材料的结构、形貌和化学组成进行了表征,并在太阳光照射下以Rh B水溶液为模拟污染物,监测CDs/TiO2纳米复合材料对Rh B的降解情况。结果表明,改变CDs的吸收度可以影响TiO2的光催化性能,来自碳核的本征吸收有助于提升光催化活性,而来自表面态的长拖尾吸收不利于光催化。此外,CDs的吸附量可以很大程度上影响染料降解效率。In this paper, carbon dots (CDs) with different absorbances are synthesized by hydrothermal method, and the effect of the absorbance of CDs on the photocatalytic activity of CDs/TiO2 nanocomposites is studied. The structure, morphology and chemical composition of CDs/TiO2 nanocomposites are characterized by transmission electron microscopy, Fourier transform infrared spectrometer and X-ray photoelectron spectrometer. The degradation of Rh B by CDs/TiO2 nanocomposites is monitored by using Rh B aqueous solution as a simulated pollutant under sunlight irradiation. The results show that changing the absorption of CDs can affect the photocatalytic performance of TiO2. The intrinsic absorption from carbon nuclei can improve photocatalytic activity, but the long-trailing absorption from surface states is not conducive to photocatalysis. In addition, the adsorption amount of CDs can greatly affect the degradation efficiency of dyes.展开更多
The direct conversion of methane into methanol under mild conditions represents a highly appealing pathway.Regulating the generation of hydroxyl radicals(·OH)is a representative method,but excessive release of...The direct conversion of methane into methanol under mild conditions represents a highly appealing pathway.Regulating the generation of hydroxyl radicals(·OH)is a representative method,but excessive release of·OH will inevitably lead to the over-oxidation of CH3OH.Here,we design AgPd alloy and Co3O4 cascade active sites on the TiO2 surface(AgPd-Co/TiO2)to control the release rate of·OH to improve the selectivity of CH3OH.By incorporating Co3O4 as a hole buffer and storage center,the kinetics of·OH generation at the TiO2 interface can be effectively modulated.This confines the spatial distribution of·OH to the active sites of the AgPd alloy,thus facilitating the directional combination of·CH3 and·OH.The optimal AgPd-Co/TiO2 photocatalyst demonstrates outstanding catalytic performance with the selectivity of CH3OH reaching up to 93%in the liquid phase.AgPd-Co/TiO2 exhibited significantly enhanced selectivity relative to reported TiO2-based photocatalytic systems,while simultaneously achieving comparable methanol yields.This research offers valuable insights for the precise design of composite photocatalysts to achieve highly selective methane oxidation.展开更多
基金Funded by Shan Xi Research Fund for Returned Scholars(No.2007-25)Shan Xi Open Fund for Key Laboratory(No.2008012013-7)The Specialized Fund for The Innovative of College Students of Tai Yuan City(No.09122018)
摘要The transparent C-doped TiO2 nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method.The as-prepared films were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),UV-visible absorption spectra(UV-vis)and X-ray photoelectron spectroscopy(XPS).The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature.The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping.The calcination temperatures significantly affect the morphology,microstructure and photocatalytic activity of the as-prepared samples.At 723 K,the C-doped TiO2 films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization,appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.
基金Supported by the National Natural Science Foundation of China under Grant No 11704161the Natural Science Foundation of Jiangsu Province under Grant Nos BK20170309 and BK20151172the Changzhou Science and Technology Bureau under Grant Nos CJ20159049 and CJ20160028
摘要We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5(C-GST) films during heating in air. Both the C-GST films without and with a thin SiO2 capping layer(C-GST and C-GST/SiO2) are deposited for comparison. Large differences are observed between C-GST and C-GST/SiO2 films in resistance-temperature, x-ray diffraction, x-ray photoelectron spectroscopy,Raman spectra, data retention capability and optical band gap measurements. In the C-GST film, resistancetemperature measurement reveals an unusual smooth decrease in resistance above 110℃ during heating. Xray diffraction result has excluded the possibility of phase change in the C-GST film below 170℃. The x-ray photoelectron spectroscopy experimental result reveals the evolution of Te chemical valence because of the carbon oxidation during heating. Raman spectra further demonstrate that phase changes from an amorphous state to the hexagonal state occur directly during heating in the C-GST film. The quite smooth decrease in resistance is believed to be related with the formation of Te-rich GeTe4-n Gen(n = 0, 1) units above 110℃ in the C-GST film. The oxidation of carbon is harmful to the C-GST phase change properties.
基金support from the Research Council of Norway provided by the Norwegian Center for Transmission Electron Microscopy,NORTEM(197405/F50)NTNU NanoLab(grant number 245963)which have provided the characterization toolsthe strategic funding support provided by Department of Chemical Engineering,NTNU,Trondheim,Norway.
摘要To achieve efficient photocatalytic H2 generation from water using earth-abundant and cost-effective materials,a simple synthesis method for carbon-doped CdS particles wrapped with graphene(C-doped CdS@G)is reported.The doping effect and the application of graphene as cocatalyst for CdS is studied for photocatalytic H2 generation.The most active sample consists of CdS and graphene(CdS-0.15G)exhibits promising photocatalytic activity,producing 3.12 mmol g^-(1) h^-(1) of H2 under simulated solar light which is^4.6 times superior than pure CdS nanoparticles giving an apparent quantum efficiency(AQY)of 11.7%.The enhanced photocatalytic activity for H2 generation is associated to the narrowing of the bandgap,enhanced light absorption,fast interfacial charge transfer,and higher carrier density(ND)in C-doped CdS@G samples.This is achieved by C doping in CdS nanoparticles and the formation of a graphene shell over the C-doped CdS nanoparticles.After stability test,the spent catalysts sample was also characterized to investigate the nanostructure.
基金support from the European Union Horizon 2020 program(project HERMES,nr.952184)the Ministry of Education,Youth and Sports of the Czech Republic for supporting CEMNAT(LM2023037)+1 种基金Czech-NanoLab(LM2023051)infrastructures for providing ALD,SEM,EDX,XPS,TEM,and XRDCzech Science Foundation(project 23-08019X,EXPRO).
摘要Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolution reaction(HER)by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H*desorption.Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8-0.4 nm NPs present on TNT layers,and it emerges with the highest HER activity among all the electrodes synthesized.A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti3+states and the coexistence of Ru SAs and NPs.With insights from literature,the role of Ti3+,appropriate work functions of TNT layers and Ru,and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified.The aforementioned characteristics led to a remarkable performance by having 9mV onset potentials and 33 mV dec-1 of Tafel slopes and a higher turnover frequency of 1.72 H2 s-1 at 30 mV.Besides,a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.
摘要利用太阳能等可再生能源已经成为解决环境和能源问题的重要研究方向。本文通过经典的模板法制备中空TiO2,考察其光催化降解罗丹明B (RhB)的活性,并通过SEM、TEM、XRD、UV-Vis等手段分析中空TiO2的形貌与结构、光电化学性能以及光催化降解机理。结果表明,在模拟太阳光照射300 min后,中空TiO2对RhB的降解率高达94.4%,降解动力学常数(k)可达0.0066 min−1,是普通TiO2的9倍。本工作可为光催化降解有机污染物提供新的思路。The utilization of renewable energy such as solar energy has become an important research direction in solving environmental and energy problems. This paper uses a classic template method to prepare hollow TiO2 and investigate its photocatalytic degradation performance of RhB. The morphology, structure, photo-electrochemical and photocatalytic degradation mechanism of hollow TiO2 is analyzed by means of SEM, TEM, XRD, UV-Vis, etc. These results indicate that after simulating solar irradiation for 300 minutes, the degradation rate of RhB by hollow TiO2 was as high as 94.4%, and the degradation kinetics constant (k) of RhB by hollow TiO2 can reach 0.0066 min-1, which is 9 times higher than that of ordinary TiO2. This work can provide new ideas for photocatalytic degradation of organic pollutants.
摘要本文采用水热法合成了具有不同吸光度的碳点(CDs),研究CDs吸光度对CDs/TiO2纳米复合材料光催化活性的影响。利用透射电子显微镜、傅里叶变换红外光谱仪、X射线光电子能谱仪对CDs/TiO2纳米复合材料的结构、形貌和化学组成进行了表征,并在太阳光照射下以Rh B水溶液为模拟污染物,监测CDs/TiO2纳米复合材料对Rh B的降解情况。结果表明,改变CDs的吸收度可以影响TiO2的光催化性能,来自碳核的本征吸收有助于提升光催化活性,而来自表面态的长拖尾吸收不利于光催化。此外,CDs的吸附量可以很大程度上影响染料降解效率。In this paper, carbon dots (CDs) with different absorbances are synthesized by hydrothermal method, and the effect of the absorbance of CDs on the photocatalytic activity of CDs/TiO2 nanocomposites is studied. The structure, morphology and chemical composition of CDs/TiO2 nanocomposites are characterized by transmission electron microscopy, Fourier transform infrared spectrometer and X-ray photoelectron spectrometer. The degradation of Rh B by CDs/TiO2 nanocomposites is monitored by using Rh B aqueous solution as a simulated pollutant under sunlight irradiation. The results show that changing the absorption of CDs can affect the photocatalytic performance of TiO2. The intrinsic absorption from carbon nuclei can improve photocatalytic activity, but the long-trailing absorption from surface states is not conducive to photocatalysis. In addition, the adsorption amount of CDs can greatly affect the degradation efficiency of dyes.
基金Supporting information is available in the online version of this article.
摘要The direct conversion of methane into methanol under mild conditions represents a highly appealing pathway.Regulating the generation of hydroxyl radicals(·OH)is a representative method,but excessive release of·OH will inevitably lead to the over-oxidation of CH3OH.Here,we design AgPd alloy and Co3O4 cascade active sites on the TiO2 surface(AgPd-Co/TiO2)to control the release rate of·OH to improve the selectivity of CH3OH.By incorporating Co3O4 as a hole buffer and storage center,the kinetics of·OH generation at the TiO2 interface can be effectively modulated.This confines the spatial distribution of·OH to the active sites of the AgPd alloy,thus facilitating the directional combination of·CH3 and·OH.The optimal AgPd-Co/TiO2 photocatalyst demonstrates outstanding catalytic performance with the selectivity of CH3OH reaching up to 93%in the liquid phase.AgPd-Co/TiO2 exhibited significantly enhanced selectivity relative to reported TiO2-based photocatalytic systems,while simultaneously achieving comparable methanol yields.This research offers valuable insights for the precise design of composite photocatalysts to achieve highly selective methane oxidation.