In this study, we report a novel and facile autoclave strategy for synthesis of near-infrared （NIR） CulnS2 QDs by employing glutathione （GSH） as capping ligand and stabilizer in aqueous media under 100 ~C. Various...In this study, we report a novel and facile autoclave strategy for synthesis of near-infrared （NIR） CulnS2 QDs by employing glutathione （GSH） as capping ligand and stabilizer in aqueous media under 100 ~C. Various experi- mental parameters including the ratio of precursors, reaction time, reaction temperature, pH effect and stability have been systematically studied. The QDs were characterized by X-ray diffraction （XRD）, transmission electron micro- scope （TEM）, and Fourier transform infrared spectroscopy （FT-IR）. The as-synthesized NIR QDs exhibited low cytotoxicity and maintained excellent cell viability even up to 100 gg/mL. After bioconjugation with Arg-Gly-Asp （RGD） peptide, the obtained CulnS2-RGD QDs have demonstrated high targeting ability with good fluorescence cell imaging performance.展开更多
The electrocatalytic carbon dioxide reduction reaction(eCO_(2)RR)into high-value-added chemicals and fuels is a promising strategy to mitigate global warming.However,it remains a significant stumbling block to the rat...The electrocatalytic carbon dioxide reduction reaction(eCO_(2)RR)into high-value-added chemicals and fuels is a promising strategy to mitigate global warming.However,it remains a significant stumbling block to the rationally tuning lattice plane of the catalyst with high activity to produce the target product in the eCO_(2)RR process.To attempt to solve this problem,the Culn bimetallic alloy nanocatalyst with specifically exposed lattice planes is modulated and electrodeposited on the nitrogen-doped porous carbon cloth by a simple two-step electrodeposition method,which induces high Faraday efficiency of 80%towards HCOO-(FEHCOO-)with a partial current density of 13.84 mA cm-2at-1.05 V(vs.RHE).Systematic characterizations and theoretical modeling reveal that the specific coexposed Culn(200)and In(101)lattice facets selectively adsorbed the key intermediate of OCHO*,reducing the overpotential of HCOOH and boosting the FEHCOO-in a wide potential window(-0.65--1.25 V).Moreover,a homogeneous distribution of Culn nanoparticles with an average diameter of merely~3.19 nm affords exposure to abundant active sites,meanwhile prohibiting detachment and agglomeration of nanoparticles during eCO_(2)RR for enhanced stability attributing to the self-assembly electrode strategy.This study highlights the synergistic effect between catalytic activity and facet effect,which opens a new route in surface engineering to tune their electrocatalytic performance.展开更多
Applications of in-situ and ex-situ spectroscopic ellipsometry （SE） are presented for the development of parametric expressions that define the real and imaginary parts （ε1, ε2） of the complex dielectric functio...Applications of in-situ and ex-situ spectroscopic ellipsometry （SE） are presented for the development of parametric expressions that define the real and imaginary parts （ε1, ε2） of the complex dielectric function spectra of thin film solar cell components. These spectra can then be utilized to analyze the structure of complete thin film solar cells. Optical and structural/compositional models of complete solar cells developed through least squares regression analysis of the SE data acquired for the complete cells enable simulations of external quantum efficiency （EQE） without the need for variable parameters. Such simulations can be compared directly with EQE measurements. From these comparisons, it becomes possible to understand in detail the origins of optical and electronic gains and losses in thin film photovoltaics （PC） technologies and, as a result, the underlying performance limitations. In fact, optical losses that occur when above-bandgap photons are not absorbed in the active layers can be distinguished from electronic losses when electron-hole pairs generated in the active layers are not collected. This overall methodology has been applied to copper indium-gallium diselenide （Culn1-xGaxSe2; CIGS） solar cells, a key commercialized thin film PV technology. CIGS solar cells with both standard thickness （〉2 μm） and thin （〈1 μm） absorber layers are studied by applying SE to obtain inputs for EQE simulations and enabling comparisons of simulated and measured EQE spectra. SE data analysis is challenging for CIGS material components and solar cells because of the need to develop an appropriate （ε1, ε2） database for the CIGS alloys and to extract absorber layer Ga profiles for accurate structural/compositional models. For cells with standard thickness absorbers, excellent agreement is found between the simulated and measured EQE, the latter under the assumption of 100% collection from the active layers, which include the CIGS bulk and CIGS/CdS heterojunction interface layers. For cells with thin absorbers, however, an observed difference between the simulated and measured EQE can be attributed to losses via carrier recombination within a- 0.15 μm thickness of CIGS adjacent to the Mo back contact. By introducing a carrier collection probability profile into the simulation, much closer agreement is obtained between the simulated and measured EQE. In addition to the single spot capability demonstrated in this study, ex-situ SE can be applied as well to generate high resolution maps of thin film multilayer structure, component layer properties and their profiles, as well as short-circuit current density predictions. Such mapping is possible due to the high measurement speed of 〈1 s per （ , 4） spectra achievable by the multichannel ellipsometer.展开更多
文摘In this study, we report a novel and facile autoclave strategy for synthesis of near-infrared （NIR） CulnS2 QDs by employing glutathione （GSH） as capping ligand and stabilizer in aqueous media under 100 ~C. Various experi- mental parameters including the ratio of precursors, reaction time, reaction temperature, pH effect and stability have been systematically studied. The QDs were characterized by X-ray diffraction （XRD）, transmission electron micro- scope （TEM）, and Fourier transform infrared spectroscopy （FT-IR）. The as-synthesized NIR QDs exhibited low cytotoxicity and maintained excellent cell viability even up to 100 gg/mL. After bioconjugation with Arg-Gly-Asp （RGD） peptide, the obtained CulnS2-RGD QDs have demonstrated high targeting ability with good fluorescence cell imaging performance.
基金supported by the“Scientific and Technical Innovation Action Plan”Basic Research Field of Shanghai Science and Technology Committee(19JC1410500)financial support from the National Natural Science Foundation of China(91645110)。
文摘The electrocatalytic carbon dioxide reduction reaction(eCO_(2)RR)into high-value-added chemicals and fuels is a promising strategy to mitigate global warming.However,it remains a significant stumbling block to the rationally tuning lattice plane of the catalyst with high activity to produce the target product in the eCO_(2)RR process.To attempt to solve this problem,the Culn bimetallic alloy nanocatalyst with specifically exposed lattice planes is modulated and electrodeposited on the nitrogen-doped porous carbon cloth by a simple two-step electrodeposition method,which induces high Faraday efficiency of 80%towards HCOO-(FEHCOO-)with a partial current density of 13.84 mA cm-2at-1.05 V(vs.RHE).Systematic characterizations and theoretical modeling reveal that the specific coexposed Culn(200)and In(101)lattice facets selectively adsorbed the key intermediate of OCHO*,reducing the overpotential of HCOOH and boosting the FEHCOO-in a wide potential window(-0.65--1.25 V).Moreover,a homogeneous distribution of Culn nanoparticles with an average diameter of merely~3.19 nm affords exposure to abundant active sites,meanwhile prohibiting detachment and agglomeration of nanoparticles during eCO_(2)RR for enhanced stability attributing to the self-assembly electrode strategy.This study highlights the synergistic effect between catalytic activity and facet effect,which opens a new route in surface engineering to tune their electrocatalytic performance.
基金supported by the Department of Energy and the National Science Foundation(NSF)under the F-PACE Program,Award Number DE-EE0005400supported by NSF Award EECS-1665172
文摘Applications of in-situ and ex-situ spectroscopic ellipsometry （SE） are presented for the development of parametric expressions that define the real and imaginary parts （ε1, ε2） of the complex dielectric function spectra of thin film solar cell components. These spectra can then be utilized to analyze the structure of complete thin film solar cells. Optical and structural/compositional models of complete solar cells developed through least squares regression analysis of the SE data acquired for the complete cells enable simulations of external quantum efficiency （EQE） without the need for variable parameters. Such simulations can be compared directly with EQE measurements. From these comparisons, it becomes possible to understand in detail the origins of optical and electronic gains and losses in thin film photovoltaics （PC） technologies and, as a result, the underlying performance limitations. In fact, optical losses that occur when above-bandgap photons are not absorbed in the active layers can be distinguished from electronic losses when electron-hole pairs generated in the active layers are not collected. This overall methodology has been applied to copper indium-gallium diselenide （Culn1-xGaxSe2; CIGS） solar cells, a key commercialized thin film PV technology. CIGS solar cells with both standard thickness （〉2 μm） and thin （〈1 μm） absorber layers are studied by applying SE to obtain inputs for EQE simulations and enabling comparisons of simulated and measured EQE spectra. SE data analysis is challenging for CIGS material components and solar cells because of the need to develop an appropriate （ε1, ε2） database for the CIGS alloys and to extract absorber layer Ga profiles for accurate structural/compositional models. For cells with standard thickness absorbers, excellent agreement is found between the simulated and measured EQE, the latter under the assumption of 100% collection from the active layers, which include the CIGS bulk and CIGS/CdS heterojunction interface layers. For cells with thin absorbers, however, an observed difference between the simulated and measured EQE can be attributed to losses via carrier recombination within a- 0.15 μm thickness of CIGS adjacent to the Mo back contact. By introducing a carrier collection probability profile into the simulation, much closer agreement is obtained between the simulated and measured EQE. In addition to the single spot capability demonstrated in this study, ex-situ SE can be applied as well to generate high resolution maps of thin film multilayer structure, component layer properties and their profiles, as well as short-circuit current density predictions. Such mapping is possible due to the high measurement speed of 〈1 s per （ , 4） spectra achievable by the multichannel ellipsometer.
