Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomi...Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.展开更多
This work studied CuO/CeO2-Co3O4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of? wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by...This work studied CuO/CeO2-Co3O4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of? wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by XRD and BET techniques. The results showed a good dispersion of CuO for 5 wt% Cu loading catalysts and showed high specific surface area of catalyst. For selective CO oxidation, both 5CuO and 30CuO catalysts could remove completely CO in the presence of excess hydrogen at 423 K and 20CuO could eliminate CO completely at 443 K. Moreover, considering the selectivity to CO oxidation, the 5CuO catalyst has shown the highest selectivity of 85% while the 30CuO catalyst obtains the selectivity of 65% at the reaction temperature of 423 K.展开更多
Earth-abundant copper-tin(CuSn)electrocatalysts are potential candidates for cost-effective and sustainable production of CO from electrochemical carbon dioxide reduction(eCO_(2)R).However,the requirement of highoverp...Earth-abundant copper-tin(CuSn)electrocatalysts are potential candidates for cost-effective and sustainable production of CO from electrochemical carbon dioxide reduction(eCO_(2)R).However,the requirement of highoverpotential for obtaining reasonable current,low Faradaic efficiencies(FE)and low intrinsic catalytic activities require the optimisation of the CuSn nanoarchitecture for the further advancement in the field.In the current work,we have optimised Sn loading on Cu gas diffusion electrodes(GDEs)by electrochemical spontaneous precipitation.Samples with various Sn loadings were tested in a three-chamber GDE reactor to evaluate their CO_(2)reduction performances.The best performance of 92%CO Faradaic efficiency at a cathodic current density of 120 mA cm^(-2)was obtained from the 20 min Sn deposited Cu_(2)O sample operated at-1.13 V vs.RHE.The electrocatalyst had~13%surface coverage of Sn on Cu GDE surface,and had Sn in oxide form and copper in metallic form.The catalyst also showed stable performance and was operable for>3 h under chronoamperometric conditions.The surface of the GDE reduces from Cu2O to Cu during eCO_(2)R and goes further reconstruction during the eCO_(2)R.This study demonstrates the potential of Cu-Sn for selective CO production at high current densities.展开更多
Room-temperature mechanical properties of Cu50Zr40Ti10-xNix（0≤x≤4,mole fraction,%） bulk metallic glasses （BMG） with aspect ratios in the range of 1：1-2.5：1 and loading rates in the range of1×10^-5-1×...Room-temperature mechanical properties of Cu50Zr40Ti10-xNix（0≤x≤4,mole fraction,%） bulk metallic glasses （BMG） with aspect ratios in the range of 1：1-2.5：1 and loading rates in the range of1×10^-5-1×10^-2s^-1were systematically investigated by room-temperatureuniaxialcompression test.In the condition of an aspect ratio of 1：1, the superplasticity can be clearly observed for Cu50Zr40Ti10BMG when the loading rate is1×10^-4s^-1, while for Cu50Zr40Ti10-xNix（x=1-3, mole fraction, %） BMGs when the loading rate is1×10^-2s^-1. The plastic strain （εp）, yielding strength （σy） and fracture strength （σf） of the studied Cu-based BMGs significantly depend on the aspect ratio and the loading rate. In addition, theσyof the studied Cu-based BMGs with an aspect ratio of 1：1 is close to the σfof those with the other aspect ratios when the loading rate is1×10^-2s^-1. The mechanism for the mechanical response to the loading rate and the aspect ratiowas also discussed.展开更多
Cu/SiO2 catalysts prepared by a convenient and efficient method using the urea hydrolysis deposition-precipitation （UHDP） technique have been proposed focusing on the effect of copper loading.The texture,structure a...Cu/SiO2 catalysts prepared by a convenient and efficient method using the urea hydrolysis deposition-precipitation （UHDP） technique have been proposed focusing on the effect of copper loading.The texture,structure and composition are systematically characterized by ICP,FTIR,N 2-physisorption,N2O chemisorption,TPR,XRD and XPS.The formation of copper phyllosilicate is observed in Cu/SiO2 catalyst by adopting UHDP method,and the amount of copper phyllosilicate is related to copper loading.It is found the structure properties and catalytic performance is profoundly affected by the amount of copper phyllosilicate.The excellent catalytic activity is attributed to the synergetic effect between Cu0 and Cu ＋.DMO conversion and EG selectivity are determined by the amount of Cu0 and Cu＋,respectively.The proper copper loading （30 wt%） provides with the highest ratio of Cu ＋ /Cu0,giving rise to the highest EG yield of 95% under the reaction conditions of p=2.0 MPa,T=473 K,H2/DMO=80 and LHSV=1.0h-1.展开更多
以液相离子交换法制备了一系列不同Cu负载量的Cu Na Y分子筛;采用XRD及N2吸附-脱附表征分子筛的微观结构和织构性质,采用动态吸附法考察其对噻吩模拟油的吸附脱硫性能,结合NH_3-TPD和Py-FTIR方法对CuNaY分子筛的酸量和有效Cu^+物种进行...以液相离子交换法制备了一系列不同Cu负载量的Cu Na Y分子筛;采用XRD及N2吸附-脱附表征分子筛的微观结构和织构性质,采用动态吸附法考察其对噻吩模拟油的吸附脱硫性能,结合NH_3-TPD和Py-FTIR方法对CuNaY分子筛的酸量和有效Cu^+物种进行定量分析,研究了CuNaY分子筛的表面酸性和铜物种形态结构对其吸附脱硫性能的影响机制。结果表明,通过改变铜负载量可有效调控改性Y分子筛的表面酸性以及铜物种化学形态;适量铜物种的引入可以最大限度的形成有效吸附位,从而获得最优吸附脱硫性能,而过量的Cu物种会在Y分子筛笼内形成多核铜物种结构,导致有效吸附位点的减少,影响其对噻吩的吸附能力。展开更多
文摘Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity.
文摘目的 单原子纳米酶(single-atom nanozyme,SAN)因其高原子利用率及丰富的类酶活性被广泛研究。但是目前大多数SAN活性位点负载量较低,限制了其进一步应用和发展。本研究旨在制备一种高原子负载量的SAN,并对其类酶活性进行系统研究,希望为高负载SAN的制备提供思路,并为SAN在更广泛领域的应用提供理论支持。方法 本研究通过原位锚定策略将金属盐前驱体锚定在氨基化石墨烯量子点框架中,在惰性气体保护下进行高温热解稳定Cu原子和载体之间的化学键,制备出负载量高达7.66%(质量百分比)的高负载Cu单原子纳米酶(high-loading Cu SAN)。此外,以3,3’,5,5’-四甲基联苯胺(TMB)和氮蓝四唑(NBT)为显色剂,评估了high-loading Cu SAN的类过氧化物酶(POD)、类氧化物酶(OXD)及类超氧化物歧化酶(SOD)活性,并与传统金属有机框架锚定法制备的低负载Cu单原子纳米酶(low-loading Cu SAN)作比较。以过氧化氢(H_(2)O_(2))为催化底物,对比研究了高/低负载Cu SAN的类过氧化氢酶(CAT)活性。结果 研究表明,本文制备的高负载Cu SAN的类POD和SOD活性分别是低负载Cu SAN的3.4倍和8.88倍,且表现出类酶催化选择性。结论 本研究为高负载SAN的制备和活性研究提供了思路,为SAN在检测传感、疾病治疗以及环境保护等方面的应用奠定了基础。
文摘This work studied CuO/CeO2-Co3O4 with wt% Ce:Co ratio 95:5 for selective CO oxidation with effect of? wt% Cu loading. The catalysts were prepared by co-precipitation. Characterizations of catalysts were carried out by XRD and BET techniques. The results showed a good dispersion of CuO for 5 wt% Cu loading catalysts and showed high specific surface area of catalyst. For selective CO oxidation, both 5CuO and 30CuO catalysts could remove completely CO in the presence of excess hydrogen at 423 K and 20CuO could eliminate CO completely at 443 K. Moreover, considering the selectivity to CO oxidation, the 5CuO catalyst has shown the highest selectivity of 85% while the 30CuO catalyst obtains the selectivity of 65% at the reaction temperature of 423 K.
基金The authors would like to acknowledge the support from the UKRI Interdisciplinary Centre for Circular Chemical Economy(EP/V011863/1)EPSRC LifesCO2R project(EP/N009746/1 EP/N009746/2)and EPSRC NECEM Energy Material Centre(EP/R021503/1)Loughborough Materials Characterisation Centre Pump Prime grant which enabled the access to the characterisation facilities is also acknowledged.
文摘Earth-abundant copper-tin(CuSn)electrocatalysts are potential candidates for cost-effective and sustainable production of CO from electrochemical carbon dioxide reduction(eCO_(2)R).However,the requirement of highoverpotential for obtaining reasonable current,low Faradaic efficiencies(FE)and low intrinsic catalytic activities require the optimisation of the CuSn nanoarchitecture for the further advancement in the field.In the current work,we have optimised Sn loading on Cu gas diffusion electrodes(GDEs)by electrochemical spontaneous precipitation.Samples with various Sn loadings were tested in a three-chamber GDE reactor to evaluate their CO_(2)reduction performances.The best performance of 92%CO Faradaic efficiency at a cathodic current density of 120 mA cm^(-2)was obtained from the 20 min Sn deposited Cu_(2)O sample operated at-1.13 V vs.RHE.The electrocatalyst had~13%surface coverage of Sn on Cu GDE surface,and had Sn in oxide form and copper in metallic form.The catalyst also showed stable performance and was operable for>3 h under chronoamperometric conditions.The surface of the GDE reduces from Cu2O to Cu during eCO_(2)R and goes further reconstruction during the eCO_(2)R.This study demonstrates the potential of Cu-Sn for selective CO production at high current densities.
基金Projects(50874045,51301194)supported by the National Natural Science Foundation of ChinaProject(2144057)supported by the Beijing Natural Science Foundation,China
文摘Room-temperature mechanical properties of Cu50Zr40Ti10-xNix（0≤x≤4,mole fraction,%） bulk metallic glasses （BMG） with aspect ratios in the range of 1：1-2.5：1 and loading rates in the range of1×10^-5-1×10^-2s^-1were systematically investigated by room-temperatureuniaxialcompression test.In the condition of an aspect ratio of 1：1, the superplasticity can be clearly observed for Cu50Zr40Ti10BMG when the loading rate is1×10^-4s^-1, while for Cu50Zr40Ti10-xNix（x=1-3, mole fraction, %） BMGs when the loading rate is1×10^-2s^-1. The plastic strain （εp）, yielding strength （σy） and fracture strength （σf） of the studied Cu-based BMGs significantly depend on the aspect ratio and the loading rate. In addition, theσyof the studied Cu-based BMGs with an aspect ratio of 1：1 is close to the σfof those with the other aspect ratios when the loading rate is1×10^-2s^-1. The mechanism for the mechanical response to the loading rate and the aspect ratiowas also discussed.
文摘Cu/SiO2 catalysts prepared by a convenient and efficient method using the urea hydrolysis deposition-precipitation （UHDP） technique have been proposed focusing on the effect of copper loading.The texture,structure and composition are systematically characterized by ICP,FTIR,N 2-physisorption,N2O chemisorption,TPR,XRD and XPS.The formation of copper phyllosilicate is observed in Cu/SiO2 catalyst by adopting UHDP method,and the amount of copper phyllosilicate is related to copper loading.It is found the structure properties and catalytic performance is profoundly affected by the amount of copper phyllosilicate.The excellent catalytic activity is attributed to the synergetic effect between Cu0 and Cu ＋.DMO conversion and EG selectivity are determined by the amount of Cu0 and Cu＋,respectively.The proper copper loading （30 wt%） provides with the highest ratio of Cu ＋ /Cu0,giving rise to the highest EG yield of 95% under the reaction conditions of p=2.0 MPa,T=473 K,H2/DMO=80 and LHSV=1.0h-1.
文摘以液相离子交换法制备了一系列不同Cu负载量的Cu Na Y分子筛;采用XRD及N2吸附-脱附表征分子筛的微观结构和织构性质,采用动态吸附法考察其对噻吩模拟油的吸附脱硫性能,结合NH_3-TPD和Py-FTIR方法对CuNaY分子筛的酸量和有效Cu^+物种进行定量分析,研究了CuNaY分子筛的表面酸性和铜物种形态结构对其吸附脱硫性能的影响机制。结果表明,通过改变铜负载量可有效调控改性Y分子筛的表面酸性以及铜物种化学形态;适量铜物种的引入可以最大限度的形成有效吸附位,从而获得最优吸附脱硫性能,而过量的Cu物种会在Y分子筛笼内形成多核铜物种结构,导致有效吸附位点的减少,影响其对噻吩的吸附能力。
