Photocatalytic ethylene production by oxidative dehydrogenation of ethane with dioxygen on ZnO-supported PdZn intermetallic nanoparticles

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: Jan. 26, 2024

Abstract The selective oxidative dehydrogenation of ethane (ODHE) is attracting increasing attention as a method for ethylene production. Typically, thermocatalysts operating at high temperatures are needed C–H activation in ethane. In this study, we describe low temperature ( < 140 °C) photocatalytic route ODHE, using O 2 the oxidant. A photocatalyst containing PdZn intermetallic nanoparticles supported on ZnO prepared, affording an production rate 46.4 mmol g –1 h with 92.6% selectivity under 365 nm irradiation. When employ simulated shale gas feed, ODHE system achieves nearly 20% conversion while maintaining about 87%. robust interface between and support plays crucial role through photo-assisted Mars-van Krevelen mechanism, followed by rapid lattice oxygen replenishment to complete reaction cycle. Our findings demonstrate that promising alkane-to-alkene conversions mild conditions.

Language: Английский

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Rapid Interlayer Charge Separation and Extended Carrier Lifetimes due to Spontaneous Symmetry Breaking in Organic and Mixed Organic–Inorganic Dion–Jacobson Perovskites

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(9), P. 5297 - 5309

Published: Feb. 24, 2023

Promising alternatives to three-dimensional perovskites, two-dimensional (2D) layered metal halide perovskites have proven their potential in optoelectronic applications due improved photo- and chemical stability. Nevertheless, photovoltaic devices based on 2D suffer from poor efficiency owing unfavorable charge carrier dynamics energy losses. Focusing the Dion-Jacobson perovskite phase that is rapidly rising popularity, we demonstrate doping of complementary cations into 3-(aminomethyl)piperidinium accelerates spontaneous separation slows down recombination, both factors improving performance. Employing ab initio nonadiabatic (NA) molecular combined with time-dependent density functional theory, cesium broadens bandgap by 0.4 eV breaks structural symmetry. Assisted thermal fluctuations, symmetry breaking helps localize electrons holes different layers activates additional vibrational modes. As a result, accelerated. Simultaneously, lifetime grows shortened coherence time between ground excited states. The established relationships composition provide guidelines toward future material discovery design solar cells.

Language: Английский

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Nuclear Quantum Effects Prolong Charge Carrier Lifetimes in Hybrid Organic–Inorganic Perovskites

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(25), P. 14112 - 14123

Published: June 19, 2023

Hybrid organic-inorganic perovskites (HOIPs) contain light hydrogen atoms that exhibit significant nuclear quantum effects (NQEs). We demonstrate NQEs have a strong effect on HOIP geometry and electron-vibrational dynamics at both low ambient temperatures, even though charges in HOIPs reside heavy elements. By combining ring-polymer molecular (MD) ab initio MD with nonadiabatic time-dependent density functional theory focusing the most studied tetragonal CH3NH3PbI3, we show increase disorder thermal fluctuations through coupling of inorganic cations to lattice. The additional induces charge localization decreases electron-hole interactions. As result, nonradiative carrier lifetimes are extended by factor 3 160 K 1/3 330 K. radiative increased 40% temperatures. fundamental band gap 0.10 0.03 eV K, respectively. enhancing atomic motions introducing new vibrational modes, strengthen Decoherence, determined elastic scattering, accelerates almost 2 due NQEs. However, coupling, driving recombination, because it is more sensitive structural distortions than HOIPs. This study demonstrates, for first time, should be considered achieve an accurate understanding evolution provides important insights design related materials optoelectronic applications.

Language: Английский

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Tuning Octahedral Tilting by Doping to Prevent Detrimental Phase Transition and Extend Carrier Lifetime in Organometallic Perovskites

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(9), P. 5393 - 5399

Published: Feb. 21, 2023

As one of the most promising materials for next-generation solar cells, organometallic perovskites have attracted substantial fundamental and applied interest. Using first-principles quantum dynamics calculations, we show that octahedral tilting plays an important role in stabilizing perovskite structures extending carrier lifetimes. Doping material with (K, Rb, Cs) ions at A-site enhances stability system relative to unfavorable phases. The doped is maximized uniform distribution dopants. Conversely, aggregation dopants inhibits associated stabilization. simulations also indicate enhanced tilting, band gap increases, coherence time nonadiabatic coupling decrease, lifetimes are thus extended. Our theoretical work uncovers quantifies heteroatom-doping stabilization mechanisms, opening up new avenues enhancing optical performance perovskites.

Language: Английский

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Origin of Phase Transitions in Inorganic Lead Halide Perovskites: Interplay between Harmonic and Anharmonic Vibrations

ACS Energy Letters, Journal Year: 2023, Volume and Issue: 8(7), P. 3016 - 3024

Published: June 16, 2023

Inorganic lead halide perovskites (ILHPs) exhibit a series of phase transitions, and stabilization the phases with desirable optoelectronic properties remains major challenge. However, intrinsic origins structural instabilities in CsPbX3 (X = Br, I) are still elusive. Herein, important role harmonic anharmonic vibrations influencing thermodynamic fluctuations ILHPs was revealed, through combined lattice dynamics multiphonon theory calculations, verified by diffraction experiments. Our results demonstrate that transition between δ- γ-CsPbI3 is driven vibrations, unveiling mysterious mechanism for stabilizing via applying strain. Moreover, successive transitions from α- to β- γ-phases vibrations. These strongly coherent phonon diffuse scattering, substantially affecting thermal conductivity carrier relaxation. This work provides guidelines maintaining favorable ILHP delicately manipulating their dynamics.

Language: Английский

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Twist Angle-Dependent Intervalley Charge Carrier Transfer and Recombination in Bilayer WS₂

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(41), P. 22826 - 22835

Published: Oct. 5, 2023

A twist angle at a van der Waals junction provides handle to tune its optoelectronic properties for variety of applications, and comprehensive understanding how the modulates electronic structure, interlayer coupling, carrier dynamics is needed. We employ time-dependent density functional theory nonadiabatic molecular elucidate angle-dependent intervalley transfer recombination in bilayer WS2. Repulsion between S atoms twisted configurations weakens increases distance, softens layer breathing modes. Twisting has minor influence on K valleys while it lowers Γ raises Q because their wave functions are delocalized layers. Consequently, reduced energy gaps accelerate hole structures. Intervalley electron proceeds nearly an order magnitude faster than transfer. The more localized values larger bandgaps result smaller couplings recombination, making 3-4 times slower high-symmetry B2g breathing, E2g in-plane, A1g out-of-plane modes most active during recombination. extended lifetimes junctions favorable device performance.

Language: Английский

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Halide Vacancies Create No Charge Traps on Lead Halide Perovskite Surfaces but Can Generate Deep Traps in the Bulk

The Journal of Physical Chemistry Letters, Journal Year: 2023, Volume and Issue: 14(26), P. 6028 - 6036

Published: June 23, 2023

Metal halide perovskites (MHPs) have attracted attention because of their high optoelectronic performance that is fundamentally rooted in the unusual properties MHP defects. By developing an ab initio-based machine-learning force field, we sample structural dynamics MHPs on a nanosecond time scale and show vacancies create midgap trap states bulk but not surface. Deep traps result from Pb-Pb dimers can form across vacancy only bulk. The required shortening distance by nearly 3 Å facilitated either charge trapping or 50 ps thermal fluctuations. large-scale deformations are possible soft. Halide surface no deep separate electrons holes, keeping charges mobile. This particularly favorable for quantum dots, which do require sophisticated passivation to emit light blink less than dots formed traditional inorganic semiconductors.

Language: Английский

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Compression Eliminates Charge Traps by Stabilizing Perovskite Grain Boundary Structures: An Ab Initio Analysis with Machine Learning Force Field

Chemistry of Materials, Journal Year: 2024, Volume and Issue: 36(6), P. 2898 - 2906

Published: March 12, 2024

Grain boundaries (GBs) play an important role in determining the optoelectronic properties of perovskites, requiring atomistic understanding underlying mechanisms. Strain engineering has recently been employed perovskite solar cells, providing a novel perspective on GBs. Here, we theoretically investigate impact axial strain geometric and electronic common CsPbBr3 GB. We develop machine learning force field perform ab initio calculations to analyze behavior GB models with different strains nanosecond time scale. Our results demonstrate that compressing efficiently suppresses structural fluctuations eliminates trap states originating from large-scale distortions. The becomes more amorphous under compressive strain, which makes relationship between structure nonmonotonic. These can help clarify conflicts experiments.

Language: Английский

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Breaking the size limitation of nonadiabatic molecular dynamics in condensed matter systems with local descriptor machine learning

Proceedings of the National Academy of Sciences, Journal Year: 2024, Volume and Issue: 121(36)

Published: Aug. 30, 2024

Nonadiabatic molecular dynamics (NA-MD) is a powerful tool to model far-from-equilibrium processes, such as photochemical reactions and charge transport. NA-MD application condensed phase has drawn tremendous attention recently for development of next-generation energy optoelectronic materials. Studies matter allow one employ efficient computational tools, density functional theory (DFT) classical path approximation (CPA). Still, system size simulation timescale are strongly limited by costly ab initio calculations electronic energies, forces, NA couplings. We resolve the limitations developing fully machine learning (ML) approach in which all above properties obtained using neural networks based on local descriptors. The ML models correlate target NA-MD, implemented with DFT CPA, directly structure. Trained small systems, applied large systems long timescales, extending capabilities orders magnitude. demonstrate dependence trapping recombination defect concentration MoS 2 . Defects provide main mechanism losses, resulting performance degradation. Charge slows decreasing concentration; however, exhibits complex dependence, conditional whether it occurs between free or trapped charges, relative concentrations carriers defects. Delocalized shallow traps can become localized increasing temperature, changing behavior. Completely ML, bridges gap theoretical realistic experimental conditions enables thousand-atom many nanoseconds.

Language: Английский

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Compression of Organic Molecules Coupled with Hydrogen Bonding Extends the Charge Carrier Lifetime in BA₂SnI₄

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(23), P. 16314 - 16323

Published: May 30, 2024

Two-dimensional (2D) metal halide perovskites, such as BA2SnI4 (BA═CH3(CH2)3NH3), exhibit an enhanced charge carrier lifetime in experiments under strain. Experiments suggest that significant compression of the BA molecule, rather than inorganic lattice, contributes to this enhancement. To elucidate underlying physical mechanism, we apply a moderate compressive strain entire system and subsequently introduce molecules. We then perform ab initio nonadiabatic molecular dynamics simulations nonradiative electron–hole recombination. observe overall lattice reduces atomic motions decreases coupling, thereby delaying Additionally, molecules enhances hydrogen bonding between iodine atoms, which lengthens Sn–I bonds, distorts [SnI6]4– octahedra, suppresses further, thus reducing coupling. Also, elongated bonds weakened antibonding interactions increase band gap. Altogether, delays recombination by more factor 3. Our provide new valuable insights into how strain, accommodated primarily organic ligands, positively influences optoelectronic properties 2D layered offering promising pathway for further performance improvements.

Language: Английский

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