Science China Materials最新文献

The development of low-cost, high-performance catalysts at the atomic scale has become a challenging issue for the large-scale applications of renewable clean energy technologies. Herein, on the basis of density functional theory calculation, we systematically investigate the effect of the local environment on the activity and selectivity of electrochemical carbon dioxide reduction reaction over single/multi-atom alloy clusters formed by the transition metal (Fe, Co, and Ni)-doped Cu13/55 clusters. Our findings reveal that the catalytic performance of multi-atom alloy clusters far exceeds that of Cu (211) surface. Notably, the Co666 configuration exhibits exceptional performance with a remarkably low free energy barrier of just 0.33 eV. Furthermore, our investigations demonstrate that catalytic performance is predominantly determined by the relative proportion of modifying metallic dopant species that generate a coordination number of 6. This ratio principally influences the adsorption strength of key intermediates (HCOO* and H₂COO*). Bader charge analyses and free energy calculations elucidate a new mechanistic pathway, wherein the hydrogenation of CO₂ at C-sites catalyzes the reduction of CO₂ to CH₄. This theoretical research provides valuable insights into the fundamental processes and energy landscapes involved in converting CO₂ to CH₄ on the studied catalytic structure, potentially paving the way for more efficient and sustainable carbon dioxide utilization strategies.

Exciplex system is a charming candidate for thermally activated delayed fluorescence (TADF) due to its intrinsic small energy difference between the lowest singlet state and triplet excited state (ΔE_ST). However, high emission efficiency and fast radiative decay rate are still a formidable task for the exciplex emission. Herein two novel tri(triazolo) triazine-based TADF emitters, named TTT-HPh-Ac and TTT-MePh-Ac, are synthesized and characterized. Using such TADF emitters as the donor molecule and (1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-dial)tris(diphenylphosphine oxide) (PO-T2T) as the acceptor molecule, the exciplex system of TTT-HPh-Ac:PO-T2T and TTT-MePh-Ac:PO-T2T are prepared, which show a tiny ΔE_ST of 40 ± 20 meV and fast reverse intersystem crossing rate. As a result, very high emission efficiency (97%) and a small non-radiative decay rate are detected for the exciplex TADF system. The solution processable organic light-emitting diode using the exciplex system as the emitter achieves a maximum external quantum efficiency (EQE_max) of 17.0%. When using the exciplex as the host matrix, the TTT-MePh-Ac:PO-T2T based solution processable device shows a better performance with an EQE_max of 20% with a very small efficiency roll-off of 6% at 1000 cd m⁻². This work proves that the molecule with both intramolecular hydrogen bonding and proper twisted molecular geometry in exciplex is more favorable to enhance its emission efficiency and suppress the non-radiative transition, which provides a new way to develop efficient and stable exciplex emitters.

MAX phases are a member of ternary carbide and nitride, with a layered crystal structure and a mixed nature of chemical bonds (covalent-ionic-metallic) that promote MAX phases embracing both ceramic and metal characteristics. As a result, MAX phase ceramics emerge with remarkable properties unique from other traditional ceramics. In this review, we focus on alternate processing approaches for MAX phases that are cost-effective and energy-saving. The MAX phase purity, formation of other unwanted phases, microstructure, and properties are influenced by many parameters during processing. Therefore, we highlight the effect of numerous factors, which alternately diminish the efficiency and performance of materials. Here, the impact of several parameters, such as starting materials, stoichiometric composition, temperature, pressure, particle size, porosity, microstructure, mechanical alloying, mechanical activation, ion irradiation, and doping, are summarized to reveal their influence on the synthesis and properties of MAX phases. The potential applications of MAX phases are considered for their development on a commercial scale toward the industry.

The creation of Cu⁰/Cu⁺ interface over Cu-based catalysts is known to facilitate the production of multi-carbon (C₂₊) products during CO₂ reduction reaction (CO₂ RR). However, the Cu⁺ moieties exhibit high susceptibility towards reduction into Cu⁰ at a high current density. Thus, a comprehensive understanding and rational shaping strategy for the construction and stabilization of Cu⁰/Cu⁺ interface in Cu-based catalysts is imperative. Herein, we proposed a controllable “nanoparticle assembly” strategy to obtain hollow spherical assemblies (HSA) composed of numerous Cu₂O nanoparticles (HSA-Cu₂O). The HSA-Cu₂O catalysts significantly enhance the selectivity of C₂₊ products, resulting in an impressive overall Faraday efficiency (FE) of 79.2% ± 0.7% at a partial current density of 317.1 mA cm⁻². The HSA-Cu₂O catalysts undergo in-situ electrochemically reconstruction during CO₂RR, achieving Cu⁰/Cu⁺ interfacial sites with a high density. The Auger electron spectra, in-situ Raman, and morphological evolution studies have confirmed that the combination of the Cu⁰/Cu⁺ interface and hollow sphere architecture facilitated the concentration of *CO intermediates, thereby promoting C–C dimerization to boost C₂₊ selectivity in CO₂RR.

Removing CO₂ impurities from C₂H₂/CO₂ mixtures is an essential process for producing high-purity C₂H₂ under high humidity. High-stability and low-cost metal-organic frameworks (MOFs) have great potential in C₂H₂/CO₂ industrial separation. However, due to the complementary adsorption of H₂O and CO₂, water vapor has a negative impact on the implementation of C₂H₂ purification. Herein, we propose a synergistic strategy of pore surface functionalization and polydimethylsiloxane (PDMS) deposition to avoid the influence of water vapor while improving C₂H₂/CO₂ separation performance. A commercially available metal-organic framework (ALP-MOF-1) was used as a template to functionalize its pore surface with CH₃, Br, and F. The optimized material ALP-MOF-1(F) exhibits the highest C₂H₂ uptake (117.78 cm³/g at 298 K and 10⁶ Pa) and C₂H₂/CO₂ uptake ratio (3.1) among ALP-MOF systems. Computational simulations show that the well-matched pore space and the significant electronegativity and polarizability of the fluorine groups on the pore surface jointly enhance the framework-C₂H₂ interaction. Furthermore, the deposition of PDMS on ALP-MOF-1 and ALP-MOF-1(F) significantly improves their C₂H₂/CO₂ separation stability under 80% humidity conditions.

The development of hydrogels capable of emitting multicolor fluorescence presents a promising avenue for addressing concerns related to information leakage and distortion of sensitive data. The integration of multifactor-induced tunable fluorescence with a unique upper critical solution temperature (UCST) behavior in hydrogels significantly contributes to the development of multi-dimensional and multi-level information storage materials that can dynamically display information as well as offer a high level of security and protection for information. However, the fusion of these advantageous properties into hydrogels intended for information storage and display remains a considerable challenge. In this context, we introduce a novel three-dimensional (3D) fluorescent code-producing hydrogel array fabricated via vat photopolymerization (VP) 3D printing, a technique offers a sustainable and efficient approach. This array unites the desired properties, capable of sequentially revealing concealed information through two distinct steps: (i) a heat-induced phase transition, and (ii) multicolor fluorescence triggered by ultraviolet (UV)/temperature exposure under specific conditions (i.e., certain UV irradiation duration, heating time, and wavelength). The reversible transparency and reprogrammable fluorescence emission properties of these hydrogels are expected to significantly enhance the processes of information encryption and anti-counterfeiting. This advancement could potentially revolutionize the field of information security.

Responsive soft materials capable of complex, reversible, and rapid geometric deformations under external stimuli hold significant potential for applications in minimally invasive medicine, wearable devices, and soft robotics. In this study, we present a novel approach for designing reconfigurable three dimensional (3D) deformable magnetic soft materials through photothermal programming. By embedding hard magnetic particles within a polymer matrix composed of fibrous polypyrrole (PPy) and semi-crystalline polymer, we develop magnetic composites that can be remotely controlled to achieve precise, programmable deformations under an external magnetic field. The key innovation lies in utilizing the photothermal effect of PPy, which temporarily alters the viscosity of the composite when irradiated with infrared light, allowing dynamic orientation of the magnetic particles. Upon cooling, the magnetic anisotropy is solidified, enabling rapid and reversible geometric changes. This method allows for intricate control over the magnetization distribution, leading to the development of multifunctional devices with various potential applications such as complex 3D deformations for soft robotics, multimodal electrical switches, rewritable quick response codes, and shape-adaptable grippers. Our study not only enhances the understanding of magnetic moment programming in soft materials but also opens new avenues for the design of adaptive and responsive materials for advanced technological applications.

CdSe quantum-dot (QD) film, as the core function layer, plays a key role in various optoelectronic devices. The thickness uniformity of QD films is one of the key factors to determine the overall photoelectric performance. Therefore, it is important to obtain the thickness distribution of large-area QD films. However, it is difficult for traditional methods to quickly get the information related to its thickness distribution without introducing additional damage. In this paper, a non-contact and non-destructive inspection method for in-situ detecting the thickness uniformity of CdSe QD film is proposed. The principle behind this in-situ inspection method is that the photoluminescence quenching phenomenon of the QD film would occur under a high electric field, and the degree of photoluminescence quenching is related to the thickness of the quantum dot films. Photoluminescence images of the same QD film without and with an electric field are recorded by a charge-coupled device camera, respectively. By transforming the brightness distribution of these two images, we can intuitively see the thickness information of the thin film array of QD. The proposed method provides a meaningful inspection for the manufacture of QD based light-emitting display.