Materials Chemistry Frontiers最新文献

The development of high-performance catalysts is an effective method to solve the severe situation in global climate change. The properties at the catalyst interface are crucial for determining the performance of catalysts. Atomic-layer deposition (ALD) can realize accurate control of the interface at the atomic level because of the self-limiting growth of materials. There are two main reasons for this phenomenon: (1) ALD offers chemical flexibility to enable building of multicomponent heterogeneous catalysts; (2) ALD can help to control substances on complex catalyst structures to produce highly conformal and uniform films, and the layer thickness can be controlled precisely at the atomic level. Herein, we summarize recent progress in catalytic materials made by ALD. We discuss in detail several common strategies for ALD to regulate active interfaces, such as construction of synergistic catalysts, as well as regulation of adsorption/desorption energy, electronic structure, and protection at the interface. Finally, we summarize the challenges of ALD technology in energy storage and transformation, and look forward to future development of ALD technology.

Correction for ‘Highly efficient dual-state emission and two-photon absorption of novel naphthalimide functionalized cyanostilbene derivatives with finely tuned terminal alkoxyl groups’ by Yingyong Ni et al., Mater. Chem. Front., 2022, 6, 3522–3530, https://doi.org/10.1039/D2QM00937D.

High mechanical properties and excellent dielectric properties are important research subjects for the application of heat-resistant poly(silylene arylacetylene)s(PSAs) in advanced wave-transparent composites. Herein, three novel poly(silylene arylacetylene)s containing the hexafluoroisopropylidene structure were synthesized by Grignard reactions. The effects of aryl ether units and –CF₃ groups on the mechanical properties, dielectric properties, and thermal stability of the cured PSA resins have been investigated. The PSA resins exhibit good solubility, processability, and high thermal stability with the temperature at 5% weight loss (T_d5) above 478 °C. Due to the introduction of flexible aryl ether units, the flexural strength of the resins arrives at over 75.1 MPa. Due to the large free volume and electronic effect of –CF₃ groups, the dielectric properties of the cured PSA resins are largely improved. The dielectric constant (ε) and dielectric loss (tan δ) reach as low as 2.53 and 2.13 × 10⁻³ at 30 MHz, respectively. Finally, quartz fiber-reinforced wave-transparent composites are prepared. The composites exhibit good mechanical properties, with the highest flexural strength and interlaminar shear strength (ILSS) reaching 395 MPa and 32.0 MPa, respectively. Meanwhile, the ε and tan δ values of the composites are below 3.26 and 3.84 × 10⁻³ in the range of 7–17 GHz, respectively, and the wave transmittances (|T|²) are higher than 91%.

It is known that the increase of catalyst loadings usually leads to activity decay owing to the increased mass transport limitations. And most catalyst electrodes are thus restricted to small mass loadings (0.1–1 mg cm⁻²). However, there are exceptions. Here we have reported the confined growth of nickel, iron-metal–organic framework (NiFe-MOF) electrodes characteristic of porous yet densely packed architectures. The NiFe-MOF electrode has shown elevated activities for the catalyst loadings increasing from 1 to 10 mg cm⁻², and achieving excellent oxygen evolution at the practical levels of catalyst loading (∼10 mg cm⁻²). Further detailed study reveals the NiFe-MOF electrode is composed of self-assembled MOF nanoribbons in 3D honeycomb architecture on a nickel foam substrate. The electrode can afford hierarchical macro–micro-porosity that facilitates fast mass transport, in addition to high catalyst loadings for securing strong durability. Consequently, NiFe-MOF electrodes are optimized to deliver the best oxygen evolution activities ever reported for MOFs, characteristic of a low overpotential of 226 mV at 10 mA cm⁻², and a prolonged stability up to 666 h at 100 mA cm⁻² or 100 h at 500 mA cm⁻².

Due to the environmental pollution and high energy consumption associated with the conventional industrial Bosch–Meiser method, electrocatalytic urea synthesis emerges as a promising and sustainable alternative route. In this work, we constructed and utilized nitrogen-doped porous carbon loaded with bimetallic FeNi₃ alloy nanoparticles as an efficient electrocatalyst for synthesizing urea from carbon dioxide (CO₂) and nitrate (NO₃⁻). The created FeNi₃ alloy within FeNi/NC served as the active site for the C–N coupling reaction, generating a higher urea yield of 496.5 μg h⁻¹ mg_cat.⁻¹ with a correlating faradaic efficiency (FE) of 16.58% at −0.9 V versus the reversible hydrogen electrode (vs. RHE), when in comparison to monometallic Fe/NC and Ni/NC catalysts. Moreover, we also monitored the urea generation process via in situ Raman spectroscopy technology, which enabled the identification of two critical reaction species, namely O–C–O and N–C–N, inferring that C–N coupling acted as the key reaction step.

Improving the overall specific capacity of electrodes is more crucial than increasing the specific capacity of active materials to create high-energy lithium-ion batteries. This study proposes a novel approach of coating high-capacity active materials on current collectors with capacity-contributing ability to produce high-performance electrodes with excellent overall specific capacity. Using this approach, a series of SiO/carbon cloth composite electrodes (SiO@W0CC) were constructed by simply coating the amorphous SiO material on the surface of a commercially available W0S1011 hydrophilic carbon cloth (W0CC). This hydrophilic carbon cloth possesses amazing multiple functions, including conducting electricity as a current collector, contributing capacity, improving the adhesion and distribution of SiO materials on its surfaces with its hydrophilic groups, and reducing the electrode expansion rate during the cyclic testing by its three-dimensional network structure. Therefore, the as-fabricated SiO@W0CC electrode exhibits significantly superior performance compared to composite electrodes fabricated by coating SiO on commercial current collectors such as a hydrophobic carbon cloth, a carbon paper, and copper foil. Moreover, the optimal SiO@W0CC electrode outperforms most similar electrodes in terms of the overall specific capacity output and exhibits promising potential as a high-capacity electrode for future lithium-ion batteries.

Carbon dioxide (CO₂) capture and conversion into valuable chemicals is a promising and sustainable way to mitigate the adverse effects of anthropogenic CO₂ and climate change. Porous polyimides (pPIs), a class of highly cross-linked porous organic polymers (POPs), are promising candidates for CO₂ capture as well as catalytic conversion to valuable chemicals. Here, two metal-free perylene-based pPIs were synthesised via polycondensation reaction. The pPIs exhibit excellent heterogeneous catalytic activities for cycloaddition of CO₂ to epoxides under very mild and sustainable conditions (slight CO₂ overpressures, solvent- and co-catalyst free at 80 °C) with 98% conversion. The effects of reaction conditions, such as reaction temperature, reaction time and catalyst loading on the cycloaddition performance were investigated. Moreover, the pPIs can be recycled and reused five times without a substantial loss of catalytic activity. Furthermore, these materials were used in the electroreduction of CO₂ to form formate and methanol with faradaic efficiencies (FEs) of 20% and 95%, respectively, in the applied potential range from 0 to −1 V vs. RHE.

Three novel porphyrin-heptazine-based conjugated organic polymers (MTPP-Cys, M = H₂, Ni, Cu) have been constructed, and an intramolecular donor–acceptor (D–A) structure has been formed by the electron-rich porphyrin and electron-deficient s-heptazine. Benefitting from the excellent light-absorbing potential of porphyrin, and significantly enhanced intramolecular charge transfer caused by directly linked porphyrin and s-heptazine, the synthesized polymers present prominent sunlight absorption even up to 1800 nm. Compared to the graphitic carbon nitride (g-C₃N₄), MTPP-Cys all show a superior photooxidation capability of 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate (1,4-DHP) under irradiation with a xenon lamp (λ > 420 nm). Notably, H₂TPP-Cy synthesized using free-base porphyrin and s-heptazine shows more than 33 times higher photooxidation efficiency than g-C₃N₄. When masking visible-light, instead of no catalytic activity with g-C₃N₄ or porphyrin monomers, MTPP-Cys can still guarantee highly efficient conversion of 1,4-DHP with only a slightly extended reaction time. This investigation will provide a new idea about reasonable design and construction of novel heptazine-based D–A type conjugated organic polymers with efficient photocatalytic performance.

Four-coordinated boron complexes are fascinating scaffolds for achieving functional luminescent materials because of their superior emission properties, biocompatibility, and stimuli responsiveness. This class of complexes occasionally exhibits aggregation- or crystallization-induced emission (AIE or CIE) properties in contrast to typical organic chromophores which show aggregation-caused quenching (ACQ). However, in some cases, slight structural modification of the complexes results in drastic changes between AIE/CIE and ACQ. Therefore, there is much room for unveiling the structure–property relationships of this class of complexes. Herein, we developed β-dialdiminate boron complexes with highly efficient fluorescence not only in crystalline states but also in the solution and amorphous states. In stark contrast, we previously reported that β-diketiminate boron complexes exhibit the CIE properties. The structural difference between them is characterized only by the substituents on the imine carbons. Theoretical calculations suggest that the excitons of the β-diketiminate complexes in solutions could be quenched through large structural deformation connecting to conical intersections, while the β-dialdiminate structures could expel such structural changes. Importantly, the absolute photoluminescence quantum yields of the β-dialdiminate boron complexes are up to 96% for crystals, 75% for solutions, 83% for amorphous films, and 76% in a polymer matrix. We applied these robust luminophores to fabricate organic light-emitting devices and to synthesize π-conjugated polymers with strong fluorescence in solutions and films. Our findings can unlock opportunities for designing new robustly luminescent materials based on chromophores which have been used only in either solution or solid states until now.