Publications by authors named "Junfa Zhu"

Tin halide perovskite (THP) has emerged as a promising lead-free material for high-performance solar cells, attracting significant attention for their potential use for energy conversion. However, the rapid crystallization of THP due to its high Lewis acidity and easy oxidation of Sn leads to poor morphology and rampant defects in the resulting perovskite films. These strongly hamper the advances in efficiency and stability in THP solar cells.

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Hydrophobic ionic liquid (HIL) engineering on the catalyst surface represents a simple yet potent direction for optimizing the CO electroreduction performance. However, the pivotal role of HIL engineering at an industrial current density is still ambiguous due to limited and conflicting research findings. Herein, HIL-engineered oxide-derived Cu porous nanoparticles with electron-delocalized groups and a specific ultramicropore structure are first constructed to facilitate CO-to-C electroreduction at ampere-level current densities.

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Continuous breakthroughs have been achieved in the photoelectric conversion efficiency (PCE) of tin-based perovskite solar cells (TPSCs) in recent years. Inspired by performance improvements observed during device storage, we identified beneficial light-induced interface doping (LIID) in the TPSCs. In situ analyses using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy reveal that ion migration and oxidation at the interface induce beneficial doping effects, enhancing carrier transport and significantly boosting device performance.

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Breaking the thermal, mechanical and lightweight performance limit of aerogels has pivotal significance on thermal protection, new energy utilization, high-temperature catalysis, structural engineering, and physics, but is severely limited by the serious discrete characteristics between grain boundary and nano-units interfaces. Herein, a thermodynamically driven surface reaction and confined crystallization process is reported to synthesize a centimeter-scale supercontinuous ZrO nanolayer on ZrO-SiO fiber aerogel surface, which significantly improved its thermal and mechanical properties with density almost unchanged (≈26 mg cm). Systematic structure analysis confirms that the supercontinuous layer achieves a close connection between grains and fibers through Zr─O─Si bonds.

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Photocatalytic oxidative coupling of methane (OCM) offers an appealing route for converting greenhouse gas into valuable C hydrocarbons. However, O as the most commonly used oxidant, tends to result in inevitable overoxidation and waste of methane feedstock. Herein, we first report a photocatalytic OCM using CO as a soft oxidant for CH production under mild conditions, where an efficient photocatalyst with unique interface sites is designed and constructed to facilitate CO adsorption and activation, while concurrently boosting CH dissociation.

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Alkali element doping has significant physical implications for two-dimensional materials, primarily by tuning the electronic structure and carrier concentration. It can enhance interface electronic interactions, providing opportunities for effective charge transfer at metal-organic interfaces. In this work, we investigated the effects of gradually increasing the level of K doping on the lattice structure and electronic properties of an organometallic coordinated Kagome lattice on a Ag(111) surface.

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  • Producing ethylene from carbon dioxide through photoreduction has been challenging due to the difficulty of C-C coupling, but this study introduces a new solution using metal atom clusters on semiconductor nanosheets.
  • The research highlights the use of Pd nanoclusters on ZnO nanosheets, demonstrating that they can facilitate the C-C coupling process needed to convert CO2 into ethylene (C2H4) in pure water.
  • Results show that the Pd-ZnO system achieved a significant formation rate of 1.03 μmol g-1 h-1 for ethylene production from atmospheric CO2, while just using ZnO alone only yielded carbon monoxide.
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Branched alkanes, which enhance the octane number of gasoline, can be produced from waste polyethylene. However, achieving highly selective production of branched alkanes presents a significant challenge in the upcycling of waste polyethylene. Here, we report a one-pot process to convert polyethylene into gasoline-range hydrocarbons (C-C) with yield of 73.

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  • Metal-oxide interfaces are important for catalytic processes, especially in methanol reactions on the CeO/Ag(111) catalyst surfaces studied under ultrahigh vacuum (UHV) conditions.
  • Scanning tunneling microscopy and other techniques revealed that submonolayer CeO films form a hexagonal lattice with fully oxidized cerium, while higher ceria coverages lead to multilayer formations.
  • Methanol interacts with these surfaces to create methoxy groups, which can decompose into formate or formaldehyde, with the submonolayer CeO exhibiting significantly lower temperatures for methoxy dehydrogenation compared to multilayer structures, highlighting the unique catalytic properties of the CeO-Ag(111) interface.
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  • - The study explores the Ullmann coupling method for synthesizing functional materials, focusing on understanding the elemental binding energy shifts and the role of atomic hydrogen.
  • - It finds that changes in the work function, rather than just the formation of new carbon-silver bonds, are key to shifts in carbon binding energy during the reaction process.
  • - The research also shows that atomic hydrogen can decompose organometallic chains while promoting hydrogenation in covalent structures, indicating its dual effects in modifying surface chemistry during Ullmann coupling.
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The recent developed bottom-up on-surface synthesis offers unprecedent opportunities for the fabrication of two-dimensional (2D) carbon-based networks with atomic precision. Hierarchical coupling approach has been proposed as an efficient strategy for improving the corresponding reaction selectivity and quality of target structures. Herein, we report the synthesis of a nitrogen-doped carbon-based network on Ag(100) utilizing a hierarchical Ullmann coupling strategy.

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Soft X-ray imaging is a powerful tool to explore the structure of cells, probe material with nanometer resolution, and investigate the energetic phenomena in the universe. Conventional soft X-ray image sensors are by and large Si-based charge coupled devices that suffer from low frame rates, complex fabrication processes, mechanical inflexibility, and required cooling below -60 °C. Here, a soft X-ray photodiode is reported based on low-cost metal halide perovskite with comparable performance to commercial Si-based device.

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  • The challenge in converting CO into carbon products stems from a significant energy barrier associated with C-C coupling.
  • Researchers employed active metal particles on metal oxide nanosheets to create dual metal pair sites that facilitate this coupling process.
  • The study demonstrates that Pd particles on NbO nanosheets lower the energy barrier for C-C coupling, leading to a highly efficient CHCOOH production rate that surpasses existing photocatalysts.
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  • * It introduces composites with dual active sites to adjust bonding configurations, enhancing the thermodynamic formation of methanol (CHOH).
  • * The CoNiS-InO nanosheet composites are confirmed to have non-chemical van der Waals interactions, showing unique ability to produce methanol while the individual components solely generate carbon monoxide.
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Free of posttransfer, on-surface synthesis (OSS) of single-atomic-layer nanostructures directly on semiconductors holds considerable potential for next-generation devices. However, due to the high diffusion barrier and abundant defects on semiconductor surfaces, extended and well-defined OSS on semiconductors has major difficulty. Furthermore, given semiconductors' limited thermal catalytic activity, initiating high-barrier reactions remains a significant challenge.

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Nanoporous graphene (NPG) materials are generated by removing internal degree-3 vertices from graphene and introducing nanopores with specific topological structures, which have been widely explored and exploited for applications in electronic devices, membranes, and energy storage. The inherent properties of NPGs, such as the band structures, field effect mobilities and topological properties, are crucially determined by the geometric structure of nanopores. On-surface synthesis is an emerging strategy to fabricate low-dimensional carbon nanostructures with atomic precision.

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Phosphorene and fullerene are representative two-dimensional (2D) and zero-dimensional (0D) nanomaterials respectively, constructing their heterodimensional hybrid not only complements their physiochemical properties but also extends their applications via synergistic interactions. This is however challenging because of their diversities in dimension and chemical reactivity, and theoretical studies predicted that it is improbable to directly bond C onto the surface of phosphorene due to their strong repulsion. Here, we develop a facile electrosynthesis method to synthesize the first phosphorene-fullerene hybrid featuring fullerene surface bonding via P-C bonds.

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While the monolayer sheet is well-established as a Mott-insulator with a finite energy gap, the insulating nature of bulk 1T-TaS crystals remains ambiguous due to their varying dimensionalities and alterable interlayer coupling. In this study, we present a unique approach to unlock the intertwined two-dimensional Mott-insulator and three-dimensional band-insulator states in bulk 1T-TaS crystals by structuring a laddering stack along the out-of-plane direction. Through modulating the interlayer coupling, the insulating nature can be switched between band-insulator and Mott-insulator mechanisms.

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  • Acetylene production from mixed α-olefins offers an eco-friendly method for selectively breaking carbon-carbon (C-C) bonds using Pd(100) surfaces.
  • The process involves the thermal cleavage of α-olefins, leading to the formation of acetylene and hydrogen, with high selectivity due to the unique 4-fold hollow sites on the Pd surface.
  • A critical challenge is that acetylene tends to remain on the surface; however, using surface alloying with gold (Au) successfully helps release acetylene as a gas, presenting a cost-effective way to produce acetylene and hydrogen.
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P-type self-doping is known to hamper tin-based perovskites for developing high-performance solar cells by increasing the background current density and carrier recombination processes. In this work, we propose a gradient homojunction structure with germanium doping that generates an internal electric field across the perovskite film to deplete the charge carriers. This structure reduces the dark current density of perovskite by over 2 orders of magnitude and trap density by an order of magnitude.

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Photocatalytic conversion of methane (CH) to ethane (CH) has attracted extensive attention from academia and industry. Typically, the traditional oxidative coupling of CH (OCM) reaches a high CH productivity, yet the inevitable overoxidation limits the target product selectivity. Although the traditional nonoxidative coupling of CH (NOCM) can improve the product selectivity, it still encounters unsatisfied activity, arising from being thermodynamically unfavorable.

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Structure-optimized bimetallic and multicomponent catalysts often outperform single-component catalysts, inspiring a detailed investigation of metal-metal and metal-support interactions in the system. We investigated the geometric and electronic structures of ceria-supported Ni-Cu particles prepared using different metal deposition sequences employing a combination of X-ray photoelectron spectroscopy, resonant photoemission spectroscopy, and infrared reflection absorption spectroscopy. The bimetallic model catalyst structure was altered by a distinct surface evolution process determined by the metal deposition sequence.

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  • The protonation in carbon dioxide reduction can lead to unpredictable outcomes, making it crucial to control reactive intermediates to guide the reaction.
  • Researchers suggest that the combination of La-Ti active sites in N-LaTiO nanosheets enhances the selective conversion of CO2 into methane.
  • The use of Fourier transform infrared spectra to track the *CHO intermediate and theoretical calculations indicate improved efficiency, resulting in a methane formation rate of 7.97 μL/h and an electron selectivity of 96.6%, outperforming many current catalysts.
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High-quality perovskite films are essential for achieving high performance of optoelectronic devices; However, solution-processed perovskite films are known to suffer from compositional and structural inhomogeneity due to lack of systematic control over the kinetics during the formation. Here, the microscopic homogeneity of perovskite films is successfully enhanced by modulating the conversion reaction kinetics using a catalyst-like system generated by a foaming agent. The chemical and structural evolution during this catalytic conversion is revealed by a multimodal synchrotron toolkit with spatial resolutions spanning many length scales.

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Targeted synthesis of acetic acid (CH COOH) from CO photoreduction under mild conditions mainly limits by the kinetic challenge of the C-C coupling. Herein, we utilized doping engineering to build charge-asymmetrical metal pair sites for boosted C-C coupling, enhancing the activity and selectivity of CO photoreduction towards CH COOH. As a prototype, the Pd doped Co O atomic layers are synthesized, where the established charge-asymmetrical cobalt pair sites are verified by X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy spectra.

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