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Dual frequency comb laser absorption spectroscopy in a 16 MW gas turbine exhaust
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Accurate determination of the total hemispherical emittance and solar absorptance of opaque surfaces at elevated temperatures
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Deciphering the Local Environment of Single-Atom Catalysts with X-ray Absorption Spectroscopy
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Synthesis of 1 nm Pd Nanoparticles in a Microfluidic Reactor: Insights from in Situ X ray Absorption Fine Structure Spectroscopy and Small-Angle X ray Scattering
In this paper we show that the temporal separation of nucleation and growth is not a necessary condition for the colloidal synthesis of monodisperse nanoparticles. The synthesis mechanism of Pd nanoparticles was determined by in situ XAFS and SAXS in a microfluidic reactor capable of millisecond up to an hour time resolution. The SAXS results showed two autocatalytic growth phases, a fast growth phase followed by a very slow growth phase. The steady increase in the number of particles throughout the two growth phases indicates the synthesis is limited by slow continuous nucleation. The transition from fast to slow growth was caused by rapid increase in bonding with the capping agent as shown by XAFS. Based on this fundamental understanding of the synthesis mechanism, we show that 1 nm monodisperse Pd nanoparticles can be synthesized at low temperature using a strong binding capping agent such as trioctylphosphine (TOP).
Ultrafast Electron Trapping and Defect-Mediated Recombination in NiO Probed by Femtosecond Extreme Ultraviolet Reflection–Absorption Spectroscopy
Understanding the chemical nature of defect sites as well as the mechanism of defect-mediated recombination is critical for the rational design of energy conversion materials with improved efficiency. Using femtosecond extreme ultraviolet (XUV) spectroscopy in conjunction with X-ray photoelectron spectroscopy (XPS), we present results on the ultrafast electron dynamics in NiO prepared with varying concentrations of defect states. We find that oxygen vacancy defects do not serve as the primary recombination center, but rather the recombination rate scales linearly with the density of Ni metal defects. This suggests that grain boundaries between Ni metal and NiO are responsible for fast carrier recombination in partially reduced NiO. Here, our kinetic model shows that the photoexcited electrons self-trap via small polaron formation on the subpicosecond time scale. Additionally, we estimate an absolute measurement of small polaron formation rates, direct versus defect-mediated recombination rates, and the small polaron diffusion coefficient in NiO. This study provides important parameters for engineering NiO based materials for solar energy harvesting applications.
In Situ X-ray Absorption Spectroscopy of PtNi-Nanowire/Vulcan XC-72R under Oxygen Reduction Reaction in Alkaline Media
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Anomalous Band Gap Behavior in Mixed Sn and Pb Perovskites Enables Broadening of Absorption Spectrum in Solar Cells
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SIMULTANEOUSLY EFFICIENT LIGHT ABSORPTION AND CHARGE SEPARATION IN WO3/BIVO4 CORE/SHELL NANOWIRE PHOTOANODE FOR PHOTOELECTROCHEMICAL WATER OXIDATION
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Nearly Total Solar Absorption in Ultrathin Nanostructured Iron Oxide for Efficient Photoelectrochemical Water Splitting
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Broadband Coherent Absorption in Chirped-Planar-Dielectric Cavities for 2D-Material-Based Photovoltaics and Photodetectors
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