The oxygen reduction reaction （ORR） is traditionally performed using noble‐metals catalysts, e.g. Pt. However, these metal‐based catalysts have the drawbacks of high costs, low selectivity, poor stabili‐ties, and...The oxygen reduction reaction （ORR） is traditionally performed using noble‐metals catalysts, e.g. Pt. However, these metal‐based catalysts have the drawbacks of high costs, low selectivity, poor stabili‐ties, and detrimental environmental effects. Here, we describe metal‐free nitrogen‐doped carbon nanoblocks （NCNBs） with high nitrogen contents （4.11%）, which have good electrocatalytic proper‐ties for ORRs. This material was fabricated using a scalable, one‐step process involving the pyrolysis of tris（hydroxymethyl）aminomethane （Tris） at 800℃. Rotating ring disk electrode measurements show that the NCNBs give a high electrocatalytic performance and have good stability in ORRs. The onset potential of the catalyst for the ORR is-0.05 V （vs Ag/AgCl）, the ORR reduction peak potential is-0.20 V （vs Ag/AgCl）, and the electron transfer number is 3.4. The NCNBs showed pronounced electrocatalytic activity, improved long‐term stability, and better tolerance of the methanol crosso‐ver effect compared with a commercial 20 wt%Pt/C catalyst. The composition and structure of, and nitrogen species in, the NCNBs were investigated using Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray diffraction. The pyroly‐sis of Tris at high temperature increases the number of active nitrogen sites, especially pyridinic nitrogen, which creates a net positive charge on adjacent carbon atoms, and the high positive charge promotes oxygen adsorption and reduction. The results show that NCNBs prepared by pyrolysis of Tris as nitrogen and carbon sources are a promising ORR catalyst for fuel cells.展开更多
Sodium percarbonate(Na_(2)CO_(3)·1.5H_(2)O_(2),SPC)has been extensively employed as a solid substitute of H_(2)O_(2)for Fenton process in water treatment,because of its high stability during the production,transp...Sodium percarbonate(Na_(2)CO_(3)·1.5H_(2)O_(2),SPC)has been extensively employed as a solid substitute of H_(2)O_(2)for Fenton process in water treatment,because of its high stability during the production,transport,storage and usage.In addition,SPC can be applied in a wider range of work pH,it is also applied as a buffer in Fenton reaction for preventing a drop in pH.Herein,we have synthesized basic copper molybdate(BCM)nanoblocks with the molecular formula of Cu_(3)(MoO_(4))_(2)(OH)_(2)as an efficient and heterogeneous catalyst for antibiotics degradation via percarbonate activation.First,fully physical characterizations confirmed BCM nanocomposite exhibited a structure of nanoblocks.We also found that BCM/SPC system could work in a much wider pH range,compared with H_(2)O_(2).Then,BCM/SPC system presented a good anti-interference ability for natural organic matter in OTC degradation.EPR results and Quenching tests confirmed that the co-presence of·CO_(3)-,·O_(2)-,1O_(2)and·OH in BCM/SPC system.展开更多
The near infrared (NIR) fluorescence enhancement by local surface plasmon resonanoce from arrayed gold (Au) nanoblocks was investigated by NIR fluorescent dyes, IR780, immobilized in hydrophobic DNA thin film on glass...The near infrared (NIR) fluorescence enhancement by local surface plasmon resonanoce from arrayed gold (Au) nanoblocks was investigated by NIR fluorescent dyes, IR780, immobilized in hydrophobic DNA thin film on glass substrates, to clarify the gap mode effect on the fluorescence enhancement. In the substrate with Dimer type Au nanoblock arrangement, average total fluorescence intensity was larger by 10.0, 2.4, and 12.4 times for non-polarized, P- and S- polarization as compared with that on a glass substrate alone, respectively. These findings suggested that enhancement of excitation light intensity at nanogap in the Dimer type Au nanoblock arrangement affected the fluorescence intensity. Average total fluorescence intensity, on the other hand, was smaller by 0.63 times as compared with that on a glass substrate alone in the checkerboard type Au array. It is suggested that the fluorescence quenching was caused by the energy transfer from the excited state of IR780 to Au nanoblocks or by the increased deactivation of excited dye molecules induced by resonance with Au nanoblocks at the checkerboard arrangement. We have firstly achieved the NIR fluorescence enhancement by LSPR due to the gap mode.展开更多
基金supported by the National Natural Science Foundation of China (21375088,21575090)Scientific Research Project of Beijing Educational Committee (KM201410028006)+1 种基金Scientific Research Base Development Program of the Beijing Municipal Commission of EducationYouth Talent Project of the Beijing Municipal Commission of Education (CIT & TCD201504072)~~
文摘The oxygen reduction reaction （ORR） is traditionally performed using noble‐metals catalysts, e.g. Pt. However, these metal‐based catalysts have the drawbacks of high costs, low selectivity, poor stabili‐ties, and detrimental environmental effects. Here, we describe metal‐free nitrogen‐doped carbon nanoblocks （NCNBs） with high nitrogen contents （4.11%）, which have good electrocatalytic proper‐ties for ORRs. This material was fabricated using a scalable, one‐step process involving the pyrolysis of tris（hydroxymethyl）aminomethane （Tris） at 800℃. Rotating ring disk electrode measurements show that the NCNBs give a high electrocatalytic performance and have good stability in ORRs. The onset potential of the catalyst for the ORR is-0.05 V （vs Ag/AgCl）, the ORR reduction peak potential is-0.20 V （vs Ag/AgCl）, and the electron transfer number is 3.4. The NCNBs showed pronounced electrocatalytic activity, improved long‐term stability, and better tolerance of the methanol crosso‐ver effect compared with a commercial 20 wt%Pt/C catalyst. The composition and structure of, and nitrogen species in, the NCNBs were investigated using Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray diffraction. The pyroly‐sis of Tris at high temperature increases the number of active nitrogen sites, especially pyridinic nitrogen, which creates a net positive charge on adjacent carbon atoms, and the high positive charge promotes oxygen adsorption and reduction. The results show that NCNBs prepared by pyrolysis of Tris as nitrogen and carbon sources are a promising ORR catalyst for fuel cells.
基金Financial support from the NSFC(Nos.21972073,22136003,21805166 and 22206188)the 111 Project of China(No.D20015)and Natural Science Foundation of Hubei Province,China(No.2022CFB275)is gratefully acknowledged。
文摘Sodium percarbonate(Na_(2)CO_(3)·1.5H_(2)O_(2),SPC)has been extensively employed as a solid substitute of H_(2)O_(2)for Fenton process in water treatment,because of its high stability during the production,transport,storage and usage.In addition,SPC can be applied in a wider range of work pH,it is also applied as a buffer in Fenton reaction for preventing a drop in pH.Herein,we have synthesized basic copper molybdate(BCM)nanoblocks with the molecular formula of Cu_(3)(MoO_(4))_(2)(OH)_(2)as an efficient and heterogeneous catalyst for antibiotics degradation via percarbonate activation.First,fully physical characterizations confirmed BCM nanocomposite exhibited a structure of nanoblocks.We also found that BCM/SPC system could work in a much wider pH range,compared with H_(2)O_(2).Then,BCM/SPC system presented a good anti-interference ability for natural organic matter in OTC degradation.EPR results and Quenching tests confirmed that the co-presence of·CO_(3)-,·O_(2)-,1O_(2)and·OH in BCM/SPC system.
文摘The near infrared (NIR) fluorescence enhancement by local surface plasmon resonanoce from arrayed gold (Au) nanoblocks was investigated by NIR fluorescent dyes, IR780, immobilized in hydrophobic DNA thin film on glass substrates, to clarify the gap mode effect on the fluorescence enhancement. In the substrate with Dimer type Au nanoblock arrangement, average total fluorescence intensity was larger by 10.0, 2.4, and 12.4 times for non-polarized, P- and S- polarization as compared with that on a glass substrate alone, respectively. These findings suggested that enhancement of excitation light intensity at nanogap in the Dimer type Au nanoblock arrangement affected the fluorescence intensity. Average total fluorescence intensity, on the other hand, was smaller by 0.63 times as compared with that on a glass substrate alone in the checkerboard type Au array. It is suggested that the fluorescence quenching was caused by the energy transfer from the excited state of IR780 to Au nanoblocks or by the increased deactivation of excited dye molecules induced by resonance with Au nanoblocks at the checkerboard arrangement. We have firstly achieved the NIR fluorescence enhancement by LSPR due to the gap mode.
