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重要研究成果

陳貴賢 博士
(2022)
Amr Sabbah, Indrajit Shown*, Mohammad Qorbani, Fang-Yu Fu, Tsai-Yu Lin, Heng-Liang Wu, Po-Wen Chung, Chih-I. Wu, Svette Reina Merden Santiago, Ji-Lin Shen, Kuei-Hsien Chen*, Li-Chyong Chen*
Nano Energy, 93, 106809 (2022).
本研究題目Boosting photocatalytic CO2 reduction in a ZnS/ZnIn2S4 heterostructure through strain-induced direct Z-scheme and a mechanistic study of molecular CO2 interaction thereon的代表性圖片
Employing direct Z-scheme semiconductor heterostructures in photocatalysis offers efficient charge carrier separation and isolation of both redox reactions, thus beneficial to reduce CO2 into solar fuels. Here, a ZnS/ZnIn2S4 heterostructure, comprising cubic ZnS nanocrystals on hexagonal ZnIn2S4 (ZIS) nanosheets, is successfully fabricated in a single-pot hydrothermal approach. The composite ZnS/ZnIn2S4 exhibits microstrain at its interface with an electric field favorable for Z-scheme. At an optimum ratio of Zn:In (~ 1:0.5), an excellent photochemical quantum efficiency of around 0.8% is reached, nearly 200-fold boost compared with pristine ZnS. Electronic levels and band alignments are deduced from ultraviolet photoemission spectroscopy and UV-Vis. Evidence of the direct Z-scheme and carrier dynamics is verified by photo-reduction experiment, along with photoluminescence (PL) and time-resolved PL. Finally, diffuse-reflectance infrared Fourier transformed spectroscopy explores the CO2 and related intermediate species adsorbed on the catalyst during the photocatalytic reaction. This microstrain-induced direct Z-scheme approach opens a new pathway for developing next-generation photocatalysts for CO2 reduction.
許良彥 博士
(2022)
Yu-Chen Wei and Liang-Yan Hsu*
Journal of Physical Chemistry Letters, 13, 9695–9702 (2022).
本研究題目Cavity-Free Quantum-Electrodynamic Electron Transfer Reactions的代表性圖片
Richard Feynman stated that “The theory behind chemistry is quantum electrodynamics”. However, harnessing quantum-electrodynamic (QED) effects to modify chemical reactions is a grand challenge and currently has only been reported in experiments using cavities due to the limitation of strong light–matter coupling. In this article, we demonstrate that QED effects can significantly enhance the rate of electron transfer (ET) by several orders of magnitude in the absence of cavities, which is implicitly supported by experimental reports. To understand how cavity-free QED effects are involved in ET reactions, we incorporate the effect of infinite one-photon states into Marcus theory, derive an explicit expression for the rate of radiative ET, and develop the concept of “electron transfer overlap”. Moreover, QED effects may lead to a barrier-free ET reaction whose rate is dependent on the energy-gap power law. This study thus provides new insights into fundamental chemical principles, with promising prospects for QED-based chemical reactions.
任祥華 博士
(2022)
Yi-Cheng Wang, Jhih-Shih You & H. H. Jen
Nature Communications 13, 4598 (2022).
本研究題目A non-Hermitian optical atomic mirror的代表性圖片
Explorations of symmetry and topology have led to important breakthroughs in quantum optics, but much richer behaviors arise from the non-Hermitian nature of light-matter interactions. A high-reflectivity, non-Hermitian optical mirror can be realized by a two-dimensional subwavelength array of neutral atoms near the cooperative resonance associated with the collective dipole modes. Here we show that exceptional points develop from a nondefective degeneracy by lowering the crystal symmetry of a square atomic lattice, and dispersive bulk Fermi arcs that originate from exceptional points are truncated by the light cone. From its nontrivial energy spectra topology, we demonstrate that the geometry-dependent non-Hermitian skin effect emerges in a ribbon geometry. Furthermore, skin modes localized at a boundary show a scale-free behavior that stems from the long-range interaction and whose mechanism goes beyond the framework of non-Bloch band theory. Our work opens the door to the study of the interplay among non-Hermiticity, topology, and long-range interaction.
羅佩凌 博士
(2022)
Pei-Ling Luo* and I-Yun Chen
Analytical Chemistry, 94, 5752 (2022).
本研究題目Synchronized two-color time-resolved dual-comb spectroscopy for quantitative detection of HOx radicals formed from Criegee intermediates的代表性圖片
A novel spectrometer has been developed based on synchronized two-color time-resolved dual-comb spectroscopy (TRDCS), enabling high-resolution hyperspectral measurements. The proposed approach with TRDCS exhibits great potential in quantitative diagnostics of multispecies and opens opportunities to decipher key reaction mechanisms in atmospheric chemistry. In this work, we perform simultaneous measurements in two distinct molecular fingerprint regions near 2.9 and 7.8 μm by employing the new approach with synchronized two-color TRDCS. Upon flash photolysis of CH2I2/O2/N2 gas mixtures, multiple reaction species, involving the simplest Criegee intermediates (CH2OO), formaldehyde (CH2O), hydroxyl (OH) and hydroperoxy (HO2) radicals are simultaneously detected with microsecond time resolution. The concentration of each molecule can be determined based on high-resolution rovibrational absorption spectroscopy. With quantitative detection and simulation of temporal concentration profiles of the targeted molecules at various conditions, the underlying reaction mechanisms and pathways related to the formation of the HOx radicals, which can be generated from decomposition of initially energized and vibrationally excited Criegee intermediates, are explored.
余慈顏 博士
(2022)
Cheng-Chieh Lin, Shing-Jong Huang, Pei-Hao Wu, Tzu-Pei Chen, Chih-Ying Huang, Ying-Chiao Wang, Po-Tuan Chen, Denitsa Radeva, Ognyan Petrov, Vladimir Gelev, Raman Sankar, Chia-Chun Chen,
Chun-Wei Chen*, Tsyr-Yan Yu*
Nature Communications, 13, 1513 (2022).
本研究題目Direct investigation of the reorientational dynamics of A-site cations in 2D organic-inorganic hybrid perovskite by solid-state NMR的代表性圖片
Limited methods are available for investigating the reorientational dynamics of A-site cations in two-dimensional organic–inorganic hybrid perovskites (2D OIHPs), which play a pivotal role in determining their physical properties. Here, we describe an approach to study the dynamics of A-site cations using solid-state NMR and stable isotope labelling. 2H NMR of 2D OIHPs incorporating methyl-d3-ammonium cations (d3-MA) reveals the existence of multiple modes of reorientational motions of MA. Rotational-echo double resonance (REDOR) NMR of 2D OIHPs incorporating 15N- and 13C-labeled methylammonium cations (13C,15N-MA) reflects the averaged dipolar coupling between the C and N nuclei undergoing different modes of motions. Our study reveals the interplay between the A-site cation dynamics and the structural rigidity of the organic spacers, so providing a molecular-level insight into the design of 2D OIHPs.
 
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