Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generatio...Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generation,is an important strategy to improve the production and selectivity of the C_(2)products.In this study,we determined that the local electric field can promote the C-C coupling reaction and enhance CO_(2)electroreduction to C_(2)products.First,finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their tips.Density functional theory(DFT)calculations proved that a large electric field can promote C-C coupling.Motivated by this prediction,we prepared a series of Cu catalysts with different curvatures.The Cu nanoneedles(NNs)exhibited the largest number of curvatures,followed by the Cu nanorods(NRs),and Cu nanoparticles(NPs).The Cu NNs contained the highest concentration of adsorbed K+,which resulted in the highest local electric field on the needles.CO adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability,and in-situ Fourier-transform infrared spectroscopy(FTIR)showed the strongest*COCO and*CO signals for the Cu NNs.These experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field,thus promoting C-C coupling.As a result,the Cu NNs show a maximum FEC_(2)of 44%for CO_(2)RR at a low potential(-0.6 V vs.RHE),which is approximately 2.2 times that of the Cu NPs.This work provides an effective strategy for enhancing the production of multi-carbon products during CO_(2)RR.展开更多
The solid state interdiffusion between NiFe204 and NiO in nitrogen atmosphere was studied by means of diffusion couple technique. NiFe204/NiO diffusion couple with plane interfaces was made by clamping method and sint...The solid state interdiffusion between NiFe204 and NiO in nitrogen atmosphere was studied by means of diffusion couple technique. NiFe204/NiO diffusion couple with plane interfaces was made by clamping method and sintering at 1 300℃ for 10 h. Scanning electronic microscopy （SEM） and energy-dispersive X-ray spectrometry （EDS） were used to analyze the microstructure and phase composition of the diffusion couples. The results indicate that a porous layer of uniform thickness forms along the NiFe2O4/NiO bonding interface and exhibits a deep penetration in the NiFe2O4 due to the Kirkendall effect. Furthermore, SEM observations reveal that the needle-like nickel ferrite precipitates form in NiO near the interface and the formation mechanism of them are inferred to be diffusion type solid-state phase changes.展开更多
利用动电位扫描(PDS),电化学阻抗谱(EIS)和线性极化电阻法(LPR),研究了石英砂沉积物覆盖下的X65管线钢在含氧盐溶液中的腐蚀行为及有机膦缓蚀剂乙二胺四亚甲基膦酸钠(EDTMPS)的作用效果.通过丝束电极(WBE)对沉积物所导致的电偶效应进行...利用动电位扫描(PDS),电化学阻抗谱(EIS)和线性极化电阻法(LPR),研究了石英砂沉积物覆盖下的X65管线钢在含氧盐溶液中的腐蚀行为及有机膦缓蚀剂乙二胺四亚甲基膦酸钠(EDTMPS)的作用效果.通过丝束电极(WBE)对沉积物所导致的电偶效应进行了测试.结果表明,沉积物覆盖下的X65钢平均腐蚀速率变缓,但伴随有局部腐蚀发生.在溶液中加注35 mg/L的EDTMPS后,裸露的X65钢电极的腐蚀速率在3 h内由0.17 mm/a降低并稳定在0.082 mm/a,沉积物覆盖下的X65钢电极在6 h内腐蚀速率由0.051 mm/a降低到0.026 mm/a并保持稳定,EDTMPS对裸钢和沉积物覆盖下的碳钢均有良好的缓蚀效果.WBE电偶效应测试结果表明,沉积物覆盖区域电位较低,表现为阳极区并伴随有严重的局部腐蚀发生.在注入35 mg/L缓蚀剂后,WBE平均电位迅速下降,阳极区域逐渐减小,在加入EDTMPS缓蚀剂24 h后,最大阳极电流密度和阳极总电流分别从0.21 m A/cm2和0.056 m A降低至0.078 m A/cm2和0.021 m A.监测数据表明,EDTMPS对沉积物覆盖所引起的电偶效应也有一定的抑制作用.展开更多
文摘Cu-based catalysts are the most promising candidates for electrochemical CO_(2)reduction(CO_(2)RR)to multi-carbon(C_(2))products.Optimizing the C-C coupling process,the rate-determining step for C_(2)product generation,is an important strategy to improve the production and selectivity of the C_(2)products.In this study,we determined that the local electric field can promote the C-C coupling reaction and enhance CO_(2)electroreduction to C_(2)products.First,finite-element simulations indicated that the high curvature of the Cu nanoneedles results in a large local electric field on their tips.Density functional theory(DFT)calculations proved that a large electric field can promote C-C coupling.Motivated by this prediction,we prepared a series of Cu catalysts with different curvatures.The Cu nanoneedles(NNs)exhibited the largest number of curvatures,followed by the Cu nanorods(NRs),and Cu nanoparticles(NPs).The Cu NNs contained the highest concentration of adsorbed K+,which resulted in the highest local electric field on the needles.CO adsorption sensor tests indicated that the Cu NNs exhibited the strongest CO adsorption ability,and in-situ Fourier-transform infrared spectroscopy(FTIR)showed the strongest*COCO and*CO signals for the Cu NNs.These experimental results demonstrate that high-curvature nanoneedles can induce a large local electric field,thus promoting C-C coupling.As a result,the Cu NNs show a maximum FEC_(2)of 44%for CO_(2)RR at a low potential(-0.6 V vs.RHE),which is approximately 2.2 times that of the Cu NPs.This work provides an effective strategy for enhancing the production of multi-carbon products during CO_(2)RR.
基金Project(50721003) supported by the National Natural Science Fund for Innovation Group of ChinaProject(2008AA030501) supported by the National High Technology Research and Development Program of China
文摘The solid state interdiffusion between NiFe204 and NiO in nitrogen atmosphere was studied by means of diffusion couple technique. NiFe204/NiO diffusion couple with plane interfaces was made by clamping method and sintering at 1 300℃ for 10 h. Scanning electronic microscopy （SEM） and energy-dispersive X-ray spectrometry （EDS） were used to analyze the microstructure and phase composition of the diffusion couples. The results indicate that a porous layer of uniform thickness forms along the NiFe2O4/NiO bonding interface and exhibits a deep penetration in the NiFe2O4 due to the Kirkendall effect. Furthermore, SEM observations reveal that the needle-like nickel ferrite precipitates form in NiO near the interface and the formation mechanism of them are inferred to be diffusion type solid-state phase changes.
文摘利用动电位扫描(PDS),电化学阻抗谱(EIS)和线性极化电阻法(LPR),研究了石英砂沉积物覆盖下的X65管线钢在含氧盐溶液中的腐蚀行为及有机膦缓蚀剂乙二胺四亚甲基膦酸钠(EDTMPS)的作用效果.通过丝束电极(WBE)对沉积物所导致的电偶效应进行了测试.结果表明,沉积物覆盖下的X65钢平均腐蚀速率变缓,但伴随有局部腐蚀发生.在溶液中加注35 mg/L的EDTMPS后,裸露的X65钢电极的腐蚀速率在3 h内由0.17 mm/a降低并稳定在0.082 mm/a,沉积物覆盖下的X65钢电极在6 h内腐蚀速率由0.051 mm/a降低到0.026 mm/a并保持稳定,EDTMPS对裸钢和沉积物覆盖下的碳钢均有良好的缓蚀效果.WBE电偶效应测试结果表明,沉积物覆盖区域电位较低,表现为阳极区并伴随有严重的局部腐蚀发生.在注入35 mg/L缓蚀剂后,WBE平均电位迅速下降,阳极区域逐渐减小,在加入EDTMPS缓蚀剂24 h后,最大阳极电流密度和阳极总电流分别从0.21 m A/cm2和0.056 m A降低至0.078 m A/cm2和0.021 m A.监测数据表明,EDTMPS对沉积物覆盖所引起的电偶效应也有一定的抑制作用.
