During the last decade,perovskite solar technologies underwent an impressive development,with power conversion efficiencies reaching 25.5%for single-junction devices and 29.8%for Silicon-Perovskite tandem configuratio...During the last decade,perovskite solar technologies underwent an impressive development,with power conversion efficiencies reaching 25.5%for single-junction devices and 29.8%for Silicon-Perovskite tandem configurations.Even though research mainly focused on improving the efficiency of perovskite photovoltaics(PV),stability and scalability remain fundamental aspects of a mature photovoltaics technology.For n-i-p structure perovskite solar cells,using poly-triaryl(amine)(PTAA)as hole transport layer(HTL)allowed to achieve marked improvements in device stability compared with other common hole conductors.For p-i-n structure,poly-triaryl(amine)is also routinely used as dopant-free hole transport layer,but problems in perovskite film growth,and its limited resistance to stress and imperfect batch-to-batch reproducibility,hamper its use for device upscaling.Following previous computational investigations,in this work,we report the synthesis of two small-molecule organic hole transport layers(BPT-1,2),aiming to solve the above-mentioned issues and allow upscale to the module level.By using BPT-1 and methylammonium-free perovskite,max.Power conversion efficiencies of 17.26%and 15.42%on a small area(0.09 cm^(2))and mini-module size(2.25 cm^(2)),respectively,were obtained,with a better reproducibility than with poly-triaryl(amine).Moreover,BPT-1 was demonstrated to yield more stable devices compared with poly-triaryl(amine)under ISOS-D1,T1,and L1 accelerated life-test protocols,reaching maximum T_(90)values>1000 h on all tests.展开更多
Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catal...Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO<sub>2</sub> buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO<sub>2</sub>.展开更多
The title compound 1-(4-chlorophenyl)-2-cyano-3-amino-3a-hydroxy-3a,3b,6,7- tetrahydro-benzo[4,5]indene 2, has been synthesized by the reductive cyclization of 2-cyano-3- (4-chlorophenyl)-3-(1-tetralon-2-yl) pro...The title compound 1-(4-chlorophenyl)-2-cyano-3-amino-3a-hydroxy-3a,3b,6,7- tetrahydro-benzo[4,5]indene 2, has been synthesized by the reductive cyclization of 2-cyano-3- (4-chlorophenyl)-3-(1-tetralon-2-yl) propionitrile 1 induced by low-valent titanium reagent and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group C2/c with a = 28.244(7), b = 14.401(3), c = 21.245(3)A,β= 115.71(2)°, V = 7786(3)A^3, Mr= 696.13, Dc = 1.188 g/cm^3, Z = 8,μ(MoKα) = 0.208 mm^-1, F(000) = 2916, R = 0.0783 and wR = 0.2350. X-ray analysis reveals that the five-membered ring (C(7)~C(l l)) adopts an envelop conformation, while the six-membered ring (C(10)~C(14), C(19)) has a half-chair conformation. Meanwhile, intermolecular H-bond interactions result in the formation of polymer.展开更多
The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradie...The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradients,have rarely been incorporated in biomimetic ceramicsbecause of the challenges in simultaneously controlling the materialstructure at multiple length scales.Here,we report the fabrication of artificial nacre with graphene oxide nanogradients in its aragonite plateletsthrough a matrix-directed mineralization method.The gradients areformed via the spontaneous accumulation of graphene oxide nanosheetson the surface of the platelets during the mineralization process,whichthen induces a lateral residual stress field in the platelets.Nanoindentation tests and mercury intrusion porosimetry demonstrate that the material's energy dissipation is enhanced both intrinsically and extrinsicallythrough the compressive stress near the platelet surface.The energydissipation density reaches 0.159±0.007 nJ/μm^(3),and the toughnessamplification is superior to that of the most advanced cer amics.Numer-ical simulations also agree with the finding that the stress field not ablycontributes to the overall energy dissipation.This work demonstratesthat the energy dissipation of biomimetic ceramics can be furtherincreased by integrating design principles spanning multiple scales.This strategy can be readily extended to the combinations of other struc-tural models for the design and fabrication of structural ceramics withcustomized and optimized performance.展开更多
The major hindrances of implementing graphene in two-dimensional(2D)electronics are both mechanical(the tendency to crumble and form ripples)and electrical(the lack of a band gap).Moreover,the inevitable structural de...The major hindrances of implementing graphene in two-dimensional(2D)electronics are both mechanical(the tendency to crumble and form ripples)and electrical(the lack of a band gap).Moreover,the inevitable structural defects in graphene have a profound influence on its physical and chemical properties.Here,we propose a family of 2D egg-tray graphenes constructed by arranging pentagon and heptagon defects in the graphene lattice based on a careful analysis of the topological distribution of minima,maxima,and saddle points.First-principles calculations show that the egg-tray graphenes are dynamically stable,and their energies,which depend on the concentration of pentagons and heptagons,are the lowest among carbon allotropes.These 2D carbon allotropes exhibit a large variation in their electronic properties,ranging from semimetallic to semiconducting,including some allotropes that have Dirac cones in their band structures.Furthermore,some egg-tray graphenes are predicted to have negative Poisson’s ratios.The adsorption of Li atoms on the egg-tray graphenes is considerably stronger than the adsorption on perfect graphene,therefore they may absorb Li more effectively than graphene,which is important for improving the performance of rechargeable Li batteries.展开更多
基金funding from the Italian Ministry of Economic Development(MISE)in the framework of the Operating Agreement with ENEA for Research on the Electric Systemfrom the Italian Ministry of University and Research(MUR)in the framework of“BEST4U”Project,PON R&I 2014-2020.L.V.,M.S.+2 种基金A.D.C.were supported by the European Union's Horizon 2020 Framework Program for funding Research and Innovation under grant agreement no.764047(ESPResSo)no.691664(UNIQUE,Cofund ERANET Action,MUR GA 775970)no.826013(IMPRESSIVE).C.C.and A.S.acknowledge MIUR Grant—Department of Excellence 2018-2022 and the European Union's Horizon 2020 Framework Program for funding Research and Innovation under grant agreement no.764047(ESPResSo).
文摘During the last decade,perovskite solar technologies underwent an impressive development,with power conversion efficiencies reaching 25.5%for single-junction devices and 29.8%for Silicon-Perovskite tandem configurations.Even though research mainly focused on improving the efficiency of perovskite photovoltaics(PV),stability and scalability remain fundamental aspects of a mature photovoltaics technology.For n-i-p structure perovskite solar cells,using poly-triaryl(amine)(PTAA)as hole transport layer(HTL)allowed to achieve marked improvements in device stability compared with other common hole conductors.For p-i-n structure,poly-triaryl(amine)is also routinely used as dopant-free hole transport layer,but problems in perovskite film growth,and its limited resistance to stress and imperfect batch-to-batch reproducibility,hamper its use for device upscaling.Following previous computational investigations,in this work,we report the synthesis of two small-molecule organic hole transport layers(BPT-1,2),aiming to solve the above-mentioned issues and allow upscale to the module level.By using BPT-1 and methylammonium-free perovskite,max.Power conversion efficiencies of 17.26%and 15.42%on a small area(0.09 cm^(2))and mini-module size(2.25 cm^(2)),respectively,were obtained,with a better reproducibility than with poly-triaryl(amine).Moreover,BPT-1 was demonstrated to yield more stable devices compared with poly-triaryl(amine)under ISOS-D1,T1,and L1 accelerated life-test protocols,reaching maximum T_(90)values>1000 h on all tests.
文摘Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO<sub>2</sub> buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO<sub>2</sub>.
基金This work was supported by the Education Committee Natural Science Foundation (No. 03KJB 150136).
文摘The title compound 1-(4-chlorophenyl)-2-cyano-3-amino-3a-hydroxy-3a,3b,6,7- tetrahydro-benzo[4,5]indene 2, has been synthesized by the reductive cyclization of 2-cyano-3- (4-chlorophenyl)-3-(1-tetralon-2-yl) propionitrile 1 induced by low-valent titanium reagent and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group C2/c with a = 28.244(7), b = 14.401(3), c = 21.245(3)A,β= 115.71(2)°, V = 7786(3)A^3, Mr= 696.13, Dc = 1.188 g/cm^3, Z = 8,μ(MoKα) = 0.208 mm^-1, F(000) = 2916, R = 0.0783 and wR = 0.2350. X-ray analysis reveals that the five-membered ring (C(7)~C(l l)) adopts an envelop conformation, while the six-membered ring (C(10)~C(14), C(19)) has a half-chair conformation. Meanwhile, intermolecular H-bond interactions result in the formation of polymer.
基金Strategic Priority Research Program of the Chinese Acad-emy of Sciences(XDB 0470000)National Key Research and Development Program of China(2018YFE0202201 and 2021YFA0715700)+4 种基金National Natural Science Foundation of China(22305240 and 22293044)Y.F.M.acknowledges the funding suported by the Students'Innovation and Entrepreneurship Foundation of USTC(XY2022S02)Double First-Class University Construction Fund from USTC(YD2060002037)New Comerstone Science FoundationThis work was parially carried out at the USTC Center for Micro-and Nanoscale Research and Fabrication.This research used Beamline BL14B and BL15U of the Shanghai Synchrotron Radiation Fa cility(SSRF).
文摘The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradients,have rarely been incorporated in biomimetic ceramicsbecause of the challenges in simultaneously controlling the materialstructure at multiple length scales.Here,we report the fabrication of artificial nacre with graphene oxide nanogradients in its aragonite plateletsthrough a matrix-directed mineralization method.The gradients areformed via the spontaneous accumulation of graphene oxide nanosheetson the surface of the platelets during the mineralization process,whichthen induces a lateral residual stress field in the platelets.Nanoindentation tests and mercury intrusion porosimetry demonstrate that the material's energy dissipation is enhanced both intrinsically and extrinsicallythrough the compressive stress near the platelet surface.The energydissipation density reaches 0.159±0.007 nJ/μm^(3),and the toughnessamplification is superior to that of the most advanced cer amics.Numer-ical simulations also agree with the finding that the stress field not ablycontributes to the overall energy dissipation.This work demonstratesthat the energy dissipation of biomimetic ceramics can be furtherincreased by integrating design principles spanning multiple scales.This strategy can be readily extended to the combinations of other struc-tural models for the design and fabrication of structural ceramics withcustomized and optimized performance.
基金Calculations are performed on NSF-funded XSEDE resources(TG-DMR130005)especially on Stampede cluster ran by TACCThis research is also supported by the National Natural Science Foundation of China(Grants no.21773083)E.Z.acknowledges the NSF(DMR-1827815)for financial support.W.L.acknowledges the Scientific Research and Developed Fund of the Zhejiang A&F University(No.2019FR006)for financial support.
文摘The major hindrances of implementing graphene in two-dimensional(2D)electronics are both mechanical(the tendency to crumble and form ripples)and electrical(the lack of a band gap).Moreover,the inevitable structural defects in graphene have a profound influence on its physical and chemical properties.Here,we propose a family of 2D egg-tray graphenes constructed by arranging pentagon and heptagon defects in the graphene lattice based on a careful analysis of the topological distribution of minima,maxima,and saddle points.First-principles calculations show that the egg-tray graphenes are dynamically stable,and their energies,which depend on the concentration of pentagons and heptagons,are the lowest among carbon allotropes.These 2D carbon allotropes exhibit a large variation in their electronic properties,ranging from semimetallic to semiconducting,including some allotropes that have Dirac cones in their band structures.Furthermore,some egg-tray graphenes are predicted to have negative Poisson’s ratios.The adsorption of Li atoms on the egg-tray graphenes is considerably stronger than the adsorption on perfect graphene,therefore they may absorb Li more effectively than graphene,which is important for improving the performance of rechargeable Li batteries.