Proton exchange membrane(PEM)water electrolysis represents a promising technology for green hydrogen production,but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal cata...Proton exchange membrane(PEM)water electrolysis represents a promising technology for green hydrogen production,but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts,especially iridium(Ir)based materials for the energy-demanding oxygen evolution reaction(OER).Herein,we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel(Ni)oxy-hydroxide supported on antimony-doped tin oxide(ATO)nanoparticles(IrNiyO_(x)/ATO,20 wt.%(Ir+Ni),y=0,1,2,and 3),aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER performance.When tested in strongly acidic electrolyte(0.1 M HClO_(4)),the optimised IrNi1Ox/ATO shows a mass activity of 1.0 mAµgIr^(−1) and a large turnover frequency of 123 s^(−1) at an overpotential of 350 mV,as well as a comparatively small Tafel slope of 50 mV dec^(−1),better than the IrOx/ATO control,particularly with a markedly reduced Ir loading of only 19.7µgIr cm^(−2).Importantly,IrNi1O_(x)/ATO also exhibits substantially better catalytic stability than other reference catalysts,able to continuously catalyse acidic OER at 10 mA cm^(−2) for 15 h without obvious degradation.Our in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir^(3+)/Ir^(4+)species are the active sites for the acidic OER.Furthermore,the performance of IrNi1Ox/ATO was also preliminarily evaluated in a membrane electrode assembly,which shows better activity and stability than other reference catalysts.The IrNi1Ox/ATO reported in this work is a promising alternative to commercial IrO_(2) based catalysts for PEM electrolysis.展开更多
Whispering gallery mode(WGM)microbubble cavities are a versatile optofluidic sensing platform owing to their hollow core geometry.To increase the light–matter interaction and,thereby,achieve higher sensitivity,thinwa...Whispering gallery mode(WGM)microbubble cavities are a versatile optofluidic sensing platform owing to their hollow core geometry.To increase the light–matter interaction and,thereby,achieve higher sensitivity,thinwalled microbubbles are desirable.However,a lack of knowledge about the precise geometry of hollow microbubbles prevents us from having an accurate theoretical model to describe the WGMs and their response to external stimuli.In this work,we provide a complete characterization of the wall structure of a microbubble and propose a theoretical model for the WGMs in this thin-walled microcavity based on the optical waveguide approach.Structural characterization of the wavelength-scale wall is enabled by focused ion beam milling and scanning electron microscopy imaging.The proposed theoretical model is verified by finite element method simulations.Our approach can readily be extended to other low-dimensional micro-/nanophotonic structures.展开更多
基金supported by the National Innovation Agency of Portugal through the project Baterias 2030(Grant No.POCI-01-0247-FEDER-046109)J R E would like to acknowledge the Fundación General CSIC’s ComFuturo programme which has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No.101034263+2 种基金The authors appreciate Dr Laura Simonelli and Dr Vlad Martin Diaconescu for their assistance in XAS measurements at the beamline BL22-CLÆSS,ALBA synchrotron(experiment AV-2022025706)R M is grateful to the Portuguese Foundation for Science and Technology(FCT)for the doctoral grant(Grant No.2021.06496.BD)R M and A M are grateful for the financial support from:LA/P/0045/2020,UIDB/00511/2020 and UIDP/00511/2020,funded by the national funds through FCT/MCTES(PIDDAC)。
文摘Proton exchange membrane(PEM)water electrolysis represents a promising technology for green hydrogen production,but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts,especially iridium(Ir)based materials for the energy-demanding oxygen evolution reaction(OER).Herein,we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel(Ni)oxy-hydroxide supported on antimony-doped tin oxide(ATO)nanoparticles(IrNiyO_(x)/ATO,20 wt.%(Ir+Ni),y=0,1,2,and 3),aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER performance.When tested in strongly acidic electrolyte(0.1 M HClO_(4)),the optimised IrNi1Ox/ATO shows a mass activity of 1.0 mAµgIr^(−1) and a large turnover frequency of 123 s^(−1) at an overpotential of 350 mV,as well as a comparatively small Tafel slope of 50 mV dec^(−1),better than the IrOx/ATO control,particularly with a markedly reduced Ir loading of only 19.7µgIr cm^(−2).Importantly,IrNi1O_(x)/ATO also exhibits substantially better catalytic stability than other reference catalysts,able to continuously catalyse acidic OER at 10 mA cm^(−2) for 15 h without obvious degradation.Our in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir^(3+)/Ir^(4+)species are the active sites for the acidic OER.Furthermore,the performance of IrNi1Ox/ATO was also preliminarily evaluated in a membrane electrode assembly,which shows better activity and stability than other reference catalysts.The IrNi1Ox/ATO reported in this work is a promising alternative to commercial IrO_(2) based catalysts for PEM electrolysis.
基金Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for Scientific Research(C)(23K04617)Grant-in-Aid for Early-Career Scientists(22K14621)。
文摘Whispering gallery mode(WGM)microbubble cavities are a versatile optofluidic sensing platform owing to their hollow core geometry.To increase the light–matter interaction and,thereby,achieve higher sensitivity,thinwalled microbubbles are desirable.However,a lack of knowledge about the precise geometry of hollow microbubbles prevents us from having an accurate theoretical model to describe the WGMs and their response to external stimuli.In this work,we provide a complete characterization of the wall structure of a microbubble and propose a theoretical model for the WGMs in this thin-walled microcavity based on the optical waveguide approach.Structural characterization of the wavelength-scale wall is enabled by focused ion beam milling and scanning electron microscopy imaging.The proposed theoretical model is verified by finite element method simulations.Our approach can readily be extended to other low-dimensional micro-/nanophotonic structures.