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
MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 ca...MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 catalysts. High temperature calcination caused the sintering of amorphous MnO_x and transforming to bulk crystalline Mn_2O_3, H_2-TPR and XPS results suggested the valence of Mn in MnO_x-CeO_2 was higher than pure MnO_x, and decreased with the increasing calcination temperature, The turnover frequency(TOF) was calculated based on the initial reducibility according to H_2-TPR quantitation and kinetic study. The TOF results indicated that the initial reducibility of amorphous MnO_x with high valence manganese ions was equivalent to the active sites for NO oxidation. It can be inferred that the amorphous MnO_x plays a key role in low-temperature NO oxidation.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
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.
基金Project supported by the National key research and development program(2016YFC0204901)the National Natural Science Foundation of China(21576207)the introduction of talent and technology cooperation plan of Tianjin(14RCGFGX00849)
摘要MnO_x-CeO_2 catalysts were synthesized to investigate the active sites for NO oxidation by varying the calcination temperature. XRD and TEM results showed that cubic CeO_2 and amorphous MnO_x existed in MnO_x-CeO_2 catalysts. High temperature calcination caused the sintering of amorphous MnO_x and transforming to bulk crystalline Mn_2O_3, H_2-TPR and XPS results suggested the valence of Mn in MnO_x-CeO_2 was higher than pure MnO_x, and decreased with the increasing calcination temperature, The turnover frequency(TOF) was calculated based on the initial reducibility according to H_2-TPR quantitation and kinetic study. The TOF results indicated that the initial reducibility of amorphous MnO_x with high valence manganese ions was equivalent to the active sites for NO oxidation. It can be inferred that the amorphous MnO_x plays a key role in low-temperature NO oxidation.
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.