Although tricobalt tetraoxide (Co3O4) exhibits excellent catalytic activity and selectivity towards CO, its inherent low response as a p-type semiconductor still needs further improvement. In this work, we report the synthesis of ultrathin nanosheet-assembled hierarchical CeO2/Co3O4 heterostructure with enhanced response towards CO through a facile solvothermal strategy using bimetallic MOFs as precursors. The results show that CeO2 nanoparticles are uniformly anchored on Co3O4 nanosheets, and the 5 mol% CeO2/Co3O4 (5CeO(2)/Co3O4) composite possesses a high specific surface area of 72.5 m(2).g(-1). Besides, the acquired 5CeO(2)/Co3O4 sensor achieves a high response of 184 % ((Rg-Ra)/Ra) toward 50 ppm CO at 200 degrees C, which is about 4.4-fold higher than that of the bare sensor based on Co3O4. Meanwhile, the 5CeO(2)/Co3O4 sensor presents a low detection limit (300 ppb), short response time (13 s) and medium recovery time (48 s), good selectivity, reproducibility, and stability within 30 days. We speculate that the formed p-n heterojunctions between Co3O4 and CeO2 and abundant oxygen vacancies synergistically boost the sensing performances. Altogether, our synthetic approach for constructing nanosheet heterostructures and p-n heterojunctions is an effective strategy for developing highly sensitive p-type oxide semiconductors sensing materials.

Increasing the surface activity of p-type oxide semiconductors, especially for Co3O4, is essential but challenging to improve the sensing performances toward CO. Herein, a strategy is proposed aiming to increase the surface activity of Co3O4 toward the oxidation of CO through gallium doping by utilizing the wet impregnation and freeze-drying approach. The synthesized Ga-doped Co3O4 (Ga-Co3O4) features a hierarchical structure assembled by nanosheets and a large surface area (65.39 m2/g), which ensures high-efficiency gas interaction and high response to CO. Moreover, the results demonstrate that this strategy promotes the formation of oxygen vacancies and increases the ratio of Co3+/Co2+ in Co3O4, resulting in an enhanced response of 5.8 toward 100 ppm CO, which is markedly higher than that of the bare Co3O4 (1.08). The sensor based on Ga-Co3O4 also presents excellent selectivity toward CO in various interfering gases and a wide concentration detection range of 1-900 ppm. The improved CO sensing performance can be put down to the increased surface activity of Co3O4 via tailoring the content of oxygen vacancy and Co3+ active sites. This study provides new perspectives and strategies for improving the gas-sensing properties of p-type oxide semiconductors.

Materials exhibiting X-ray-induced photochromism have consistently piqued the interest of researchers. Exploring the photochromic properties of such materials is valuable for understanding the structural changes and electron transfer processes that occur under high energy radiation, such as X-ray irradiation. Here, a crystalline silver(I) nanocluster synthesized from tert-butylacetylene silver was found to have the ability to exhibit color and photoluminescence changes upon exposure to X-ray radiation. The responsive behavior was observed across a wide temperature range of 100-300 K, with the ability to respond particularly well to soft X-rays (λ > 1 Å) and exhibit light responsiveness to hard X-rays (λ < 1 Å). By combining experimental findings including X-ray diffraction, X-ray photoelectron spectroscopy, electron spin resonance, etc. with theoretical calculations, we have proposed that X-ray irradiation induces electron transfer from chloride (Cl-) located in the center of the silver(I) nanocluster to the surrounding Ag14 in the skeleton. This represents the first documented example in which electron transfer induced by X-ray excitation has been observed, accompanied by a photochromism process, in silver nanoclusters. This study contributes to our understanding of X-ray-induced photochromism and the electron transfer process in silver cluster compounds. It also provides valuable insights and potential design strategies for applications such as photochromism, photoluminescence color change, and photoenergy conversion.

Coinage metal (Au, Ag, Cu) cluster and polyoxometalate (POM) cluster represent two types of subnanometer "artificial atoms" with significant potential in catalysis, sensing, and nanomedicine. While composite clusters combining Ag/Cu clusters with POM have achieved considerable success, the assembly of gold clusters with POM is still lagging. Herein, we first designedly synthesized two cluster structural units: an Au3O cluster stabilized by diverse N-heterocyclic carbene (NHC) ligands and an amine-terminated POM linker. The subsequent reaction involved amine substitution in the POM linker for the central O atom in the Au3O cluster, resulting in the first ternary composite cluster-a POM cluster sandwiched by two Au clusters protected by NHCs. Single-crystal X-ray diffraction and other characteristic methods characterized their atomically precise structures. Furthermore, altering the NHC ligands decreased the number of gold atoms in the sandwich structures, accompanying the different protonated degrees of amine ligand in the terminal end of the POM linker. These composite clusters showed excellent performances in catalytic H2O2 conversion through the synergistic effect between gold clusters and POM clusters. This work opens a new avenue to functional composite metal clusters and would promote their enhanced catalysis applications through intercluster synergistic interactions within composite systems.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Introducing sulfonic acid groups into MOF materials is one of the effective approaches to enhance proton conduction. Here, we attempted to prepare a new post-modified ZIF-90-based material by addition reaction of the aldehyde group with bisulfite to obtain partially functionalized ZIF-90-SO3Na(2.3). ZIF-90-SO3Na(2.3) exhibits a high proton conductivity of 2.26 × 10-2 S cm-1 at 98% RH and 100 °C.

In this study, an alkynyl-modified aromatic dicarboxylic acid bifunctional ligand was selected to construct lanthanide compound {[Eu 4 (ebdc) 6 (4,4-bpy) 0.5 (H 2 O) 4.5 ]·(C 2 H 5 OH) 1.25 (H 2 O)} n (Eu-MOF, H 2 ebdc = 5-ethynyl-isophthalic acid, 4,4-bpy = 4,4-bipyridine, and MOF = metal-organic framework), of which the uncoordinated alkynyl group would be used to anchor silver nanoclusters (Ag NCs). The Eu-MOF exhibits double emission peaks, located at 492 and 611 nm, respectively, in which the high-energy blue emission is associated with alkynyl-modified ligand while the low-energy red emission belongs to characteristic emission of Eu 3+ , indicating that ligands can effectively sensitize Eu 3+ luminescence. The intensity ratio of the dual emission fluorescence peaks of Eu-MOF displays a good linear relationship with temperature, which realizes the detection function in the low temperature region of 75–275 K, and the thermal sensitivity reaches 1.5398%·K −1 . After anchoring the Ag NCs, the high-energy blue emission is significantly quenched, indicating that the Ag NCs are indeed confined into the framework and interact with the alkynyl group, and thus change the overall electronic distribution. This is the first case of anchoring Ag NCs by a luminescent Eu-MOF and studying nanocluster loading by using spectroscopic properties. In addition, the Ag NCs@Eu-MOF also shows a good catalytic activity for cycloaddition reaction from CO 2 and epoxides. This study not only provides ideas for exploring the changes in optical properties of luminescent MOFs and Ag NCs caused by confinement effect, but also expands their potential applications in various fields.