Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu...Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu nano-sea urchins(PdCu NSUs)featured with high-curvature nanotips,by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions.PdCu NSUs exhibit excellent activity for ethanol electrooxidation,with a specific activity of 4.11 mA cm^(-2)and a mass activity of 2.24 mAμg_(Pd)^(-1),and a high Faraday efficiency(FE)of 96.4%toward acetic acid.COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips,resulting in enrichment of OH^(-)at the catalyst surface to promote the formation of Pd-OH_(ads),a species required by ethanol dehydrogenation.Furthermore,DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy,which facilitates the desorption of the produced acetic acid.This work provides a new electrocata lytic material with high-curvature nanotips,and also clarifies how the material morphology,by inducing local electric fields,affects the interfacial microenvironment and thus the catalytic activity and selectivity.展开更多
Gallium nitride(GaN),owing to its excellent properties,has emerged as a promising material for wide range of applications.However,due to the high hardness and outstanding chemical stability of GaN,the efficiency of it...Gallium nitride(GaN),owing to its excellent properties,has emerged as a promising material for wide range of applications.However,due to the high hardness and outstanding chemical stability of GaN,the efficiency of its chemical mechanical polishing(CMP)is relatively low.Photoelectrochemical mechanical polishing(PECMP)has emerged as a highly effective technique for GaN polishing.However,the development of appropriate slurry for PECMP remains a pressing issue,as achieving an optimal balance among electrical conductivity,transmittance,and particle stability is particularly challenging.This research delves into novel slurry designed for GaN PECMP.A systematic investigation is conducted to explore the impact of electrolyte type,concentration,temperature and pH on the performance of the slurry,and conducted PECMP test to evaluate performance of silica sol mixed electrolyte in PECMP.Results indicate that among the electrolytes tested,monovalent cations,particularly in the case of 0.2 M Li_(2)SO_(4) provided a favorable balance,enhancing conductivity considerably while largely maintaining high UV transmittance and particle dispersion stability over the experimental period.In contrast,divalent cations induce severe aggregation,degrading polishing performance.pH experiment reveals the stability of silica sol arises from the synergistic interplay of surface electrical properties,electrolyte characteristics,and the intrinsic chemical stability of the material PECMP test confirms that aggregated particles from unstable slurries cause surface scratches and pits.Under optimized conditions(0.2 M Li_(2)SO_(4),20 nm silica at 5 wt%),the slurry achieved a surface finish with S_(a) 0.292 nm.These results provide profound insights for the design of advanced PECMP slurries and make a significant contribution to the continuous development of GaN wafer manufacturing technology.展开更多
基金financially supported by the Major Fundamental Research of Natural Science Foundation of Shandong Province(ZR2022ZD10)National Natural Science Foundation of China(22478211,22372017)+2 种基金Postdoctoral Fellowship Program of CPSF(GZC20231193)Liaoning Binhai Laboratory(LBLG-2024-10)Qingdao Postdoctoral Applied Research Project(QDBSH20240102068)。
文摘Electrocatalysis,a form of heterogeneous catalysis,is closely associated with both catalyst properties and the catalyst/electrolyte interfacial microenvironment.Herein,we rationally design and synthesize a unique PdCu nano-sea urchins(PdCu NSUs)featured with high-curvature nanotips,by which the interfacial microenvironment is expected to be tailored to the electrocatalytic reactions.PdCu NSUs exhibit excellent activity for ethanol electrooxidation,with a specific activity of 4.11 mA cm^(-2)and a mass activity of 2.24 mAμg_(Pd)^(-1),and a high Faraday efficiency(FE)of 96.4%toward acetic acid.COMSOL finite element simulations confirm that the unique nanotips could induce a local electric field due to the accumulation of positive charges in the nanotips,resulting in enrichment of OH^(-)at the catalyst surface to promote the formation of Pd-OH_(ads),a species required by ethanol dehydrogenation.Furthermore,DFT calculations and in-situ electrochemical Fourier transform infrared spectroscopy discover that the d-band center of Pd significantly downshifts in PdCu alloy,which facilitates the desorption of the produced acetic acid.This work provides a new electrocata lytic material with high-curvature nanotips,and also clarifies how the material morphology,by inducing local electric fields,affects the interfacial microenvironment and thus the catalytic activity and selectivity.
基金supported by the National Natural Science Foundation of China(52325506).
文摘Gallium nitride(GaN),owing to its excellent properties,has emerged as a promising material for wide range of applications.However,due to the high hardness and outstanding chemical stability of GaN,the efficiency of its chemical mechanical polishing(CMP)is relatively low.Photoelectrochemical mechanical polishing(PECMP)has emerged as a highly effective technique for GaN polishing.However,the development of appropriate slurry for PECMP remains a pressing issue,as achieving an optimal balance among electrical conductivity,transmittance,and particle stability is particularly challenging.This research delves into novel slurry designed for GaN PECMP.A systematic investigation is conducted to explore the impact of electrolyte type,concentration,temperature and pH on the performance of the slurry,and conducted PECMP test to evaluate performance of silica sol mixed electrolyte in PECMP.Results indicate that among the electrolytes tested,monovalent cations,particularly in the case of 0.2 M Li_(2)SO_(4) provided a favorable balance,enhancing conductivity considerably while largely maintaining high UV transmittance and particle dispersion stability over the experimental period.In contrast,divalent cations induce severe aggregation,degrading polishing performance.pH experiment reveals the stability of silica sol arises from the synergistic interplay of surface electrical properties,electrolyte characteristics,and the intrinsic chemical stability of the material PECMP test confirms that aggregated particles from unstable slurries cause surface scratches and pits.Under optimized conditions(0.2 M Li_(2)SO_(4),20 nm silica at 5 wt%),the slurry achieved a surface finish with S_(a) 0.292 nm.These results provide profound insights for the design of advanced PECMP slurries and make a significant contribution to the continuous development of GaN wafer manufacturing technology.
