The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the sol...The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(ISs)embedded in poly(methyl methacrylate)(PMMA)coated on the surface of commercial Si-based PV cells.The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell.By tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV cell.The overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).展开更多
In this work,an alternative alkali-activated cement(AAC)made of ladle slag precursor mixed with sodium hydroxide and sodium silicate has been developed to enhance the bearing capacity of estuarine soils in coastal con...In this work,an alternative alkali-activated cement(AAC)made of ladle slag precursor mixed with sodium hydroxide and sodium silicate has been developed to enhance the bearing capacity of estuarine soils in coastal conditions via deep soil mixing(DSM).The AAC was optimized to use a low reactivity precursor(ladle slag)and to deal with a contaminated high-water content natural sediment cured under water.The material performance was analysed by comparison to a mixture made with Portland cement and cured in the same conditions.Flexural and unconfined compressive strength tests as well as seismic waves measurements after 3-,7-,14-and 28-d curing were performed to obtain a relationship between elastic stiffness and strength with curing time for both mixtures.Remarkably,the AAC mix demonstrated superior strength results,exhibiting almost double flexural and compressive strengths after 28 d compared to the Portland cement mix.The AAC mix also showed a higher rate of stiffness increase than the Portland cement mix,which has a higher initial stiffness at young ages but lower stiffness evolution.Leachate analysis confirmed that the proposed AAC could effectively immobilise any contaminants from soil or precursors.The effect of curing under stress was analysed in triaxial compression tests and found to be insignificant,indicating that laboratory data obtained without stress curing can represent the material's behaviour in a DSM column,which will cure under the weight of the column.展开更多
Dialysis plays a crucial role in the purification of nanomaterials but its impact on the structural properties of carbon nanomaterials was never investigated.Herein,a carbon-based nanomaterial generated electrochemica...Dialysis plays a crucial role in the purification of nanomaterials but its impact on the structural properties of carbon nanomaterials was never investigated.Herein,a carbon-based nanomaterial generated electrochemically in potassium phosphate buffer,was characterized before and after dialysis against pure water.It is shown that dialysis affects the size of the carbon domains,structural organization,surface functionalization,oxidation degree of carbon,and grade of amorphicity.Accordingly,dialysis drives the nanomaterial organization from discrete roundish carbon domains,with sizes ranging from 70 to 160 nm,towards linear stacking structures of small nanoparticles(<15 nm).In parallel,alcohol and ether(epoxide)surface groups evolve into more oxidized carbon groups(e.g.,ketone and ester groups).Investigation of the as-prepared nanomaterial by electron paramagnetic resonance(EPR)revealed a resonance signal consistent with carbon-oxygen centred radicals.Additionally,this study brings to light the selective affinity of the carbon nanomaterial under study to capture Na^(+)ions,a property greatly enhanced by the dialysis process,and its high ability to trap oxygen,particularly before dialysis.These findings open new perspectives for the application of carbon-based nanomaterials and raise awareness of the importance of structural changes that can occur during the purification of carbon-based nanomaterials.展开更多
基金Project supported by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership in the frame of Operational Competitiveness and Internationalization Programme(projects UIDB/50011/2020&UIDP/50011/2020,UID/EEA/50008/2020,UID/QUI/50006/2019,CENTRO-01-0145-FEDER-030186,CENTRO-01-0145-FEDER-000005,Pest-OE/QUI/UI0616/2014,POCI-01-0145-FEDER-016884,PTDC/CTM-NAN/0956/2014,UID/QUI/00686/2016,UID/QUI/00686/2018,UID/QUI/00686/2019 and NORTE-01-0145-FEDER-030858)。
文摘The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy conversion.This aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(ISs)embedded in poly(methyl methacrylate)(PMMA)coated on the surface of commercial Si-based PV cells.The IS-PMMA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV cell.By tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV cell.The overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).
基金funding from CNPq(Brazilian council for scientific and technological development)through 201465/2015-9 scholarship of the“Science without borders”programsupport of MCTES/FCT(Portuguese Science and Technology Foundation of Portuguese Ministry of Science and Technology)through CEECIND/04583/2017 grant+1 种基金financially supported by:Base Funding-UIDB/04708/2020 of the CONSTRUCT-Instituto de I&D em Estruturas e Construções-funded by national funds through FCT/MCTES(PIDDAC)A special acknowledgment is also due to the Portuguese National Steel Industry of Maia,part of MEGASA group,for the steel slag supply and to Professor Joaquim Faria for his support in understanding the basic notions of chemistry.
文摘In this work,an alternative alkali-activated cement(AAC)made of ladle slag precursor mixed with sodium hydroxide and sodium silicate has been developed to enhance the bearing capacity of estuarine soils in coastal conditions via deep soil mixing(DSM).The AAC was optimized to use a low reactivity precursor(ladle slag)and to deal with a contaminated high-water content natural sediment cured under water.The material performance was analysed by comparison to a mixture made with Portland cement and cured in the same conditions.Flexural and unconfined compressive strength tests as well as seismic waves measurements after 3-,7-,14-and 28-d curing were performed to obtain a relationship between elastic stiffness and strength with curing time for both mixtures.Remarkably,the AAC mix demonstrated superior strength results,exhibiting almost double flexural and compressive strengths after 28 d compared to the Portland cement mix.The AAC mix also showed a higher rate of stiffness increase than the Portland cement mix,which has a higher initial stiffness at young ages but lower stiffness evolution.Leachate analysis confirmed that the proposed AAC could effectively immobilise any contaminants from soil or precursors.The effect of curing under stress was analysed in triaxial compression tests and found to be insignificant,indicating that laboratory data obtained without stress curing can represent the material's behaviour in a DSM column,which will cure under the weight of the column.
基金FCT(Portugal's Foundation for Science and Technology)for financial support through the CQ-VR(UIDB/00616/2020,UIDP/00616/2020),CQE/Institute of Molecular Sciences(UIBD/00100/2020,UIPD/00100/2020 and LA/P/0056/2020),Institute for Bioengineering and Biosciences-iBB/Associate Laboratory Institute for Health and Bioeconomy-i4HB(UIDB/04565/2020,UIDP/04565/2020,and LA/P/0140/2020)FCT,MCTES,ESF,and EU through the individual research Ph.D.for the Ph.D.scholarship(SFRH/BD/138425/2018)+1 种基金FCT for funding through the Scientific Employment Stimulus—Institutional Call(Ref.CEECINST/00136/2021)the EPSRC funded National Research Facility(EP/W014521/1)。
文摘Dialysis plays a crucial role in the purification of nanomaterials but its impact on the structural properties of carbon nanomaterials was never investigated.Herein,a carbon-based nanomaterial generated electrochemically in potassium phosphate buffer,was characterized before and after dialysis against pure water.It is shown that dialysis affects the size of the carbon domains,structural organization,surface functionalization,oxidation degree of carbon,and grade of amorphicity.Accordingly,dialysis drives the nanomaterial organization from discrete roundish carbon domains,with sizes ranging from 70 to 160 nm,towards linear stacking structures of small nanoparticles(<15 nm).In parallel,alcohol and ether(epoxide)surface groups evolve into more oxidized carbon groups(e.g.,ketone and ester groups).Investigation of the as-prepared nanomaterial by electron paramagnetic resonance(EPR)revealed a resonance signal consistent with carbon-oxygen centred radicals.Additionally,this study brings to light the selective affinity of the carbon nanomaterial under study to capture Na^(+)ions,a property greatly enhanced by the dialysis process,and its high ability to trap oxygen,particularly before dialysis.These findings open new perspectives for the application of carbon-based nanomaterials and raise awareness of the importance of structural changes that can occur during the purification of carbon-based nanomaterials.
