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The electrochemical activity and stability of multimetallic nanomaterials can be improved by adjusting the structure, morphology, and composition. Herein, trimetallic AuAgPt nanowires (AuAgPt-NWs) are achieved by the galvanic replacement reaction (GRR). The corrugated one-dimensional structure of AuAgPt-NWs increases catalytically active sites and improves chemical stability. Meanwhile, the special localized surface plasmon resonance (LSPR) response of Au nanomaterials further enhances their electrocatalytic activity under light irradiation conditions. For the formic acid oxidation reaction, Au6.4Ag2.6Pt1.0-NWs exhibit a high mass activity (3081.25 mA mgpt−1), which is 24.4 times higher than that of commercial Pt nanoparticles (126.38 mA mgpt−1). Au6.4Ag2.6Pt1.0-NWs also show enhanced electrocatalytic activity relative to commercial Pt nanoparticles for the hydrogen evolution reaction at 10 mA cm−2. Under light conditions, the electrolysis system of Au6.4Ag2.6Pt1.0-NWs only needs a voltage of 0.33 V to achieve H2 production, which originates from the excellent bifunctional electrocatalytic performance of Au6.4Ag2.6Pt1.0-NWs and the photothermal effect caused by LSPR. [ABSTRACT FROM AUTHOR]

It is of great challenge to produce highly pure C2H2 from the CO2/C2H2 mixture because of their similar physical properties. Metal–organic frameworks (MOFs) have shown great potential in purifying C2H2 by virtue of their versatile pore environment with excellent tunability. However, the rational exploration of ideal MOF adsorbents with CO2-preferred CO2/C2H2 separation performance (also called inverse C2H2/CO2 separation) is extremely difficult. In this work, we demonstrate a new Zn-MOF family (SNNU-334–336) with special CO2-preferred CO2/C2H2 separation performance, which can be rationally controlled by functional groups as well as temperature. Notably, SNNU-334–336 MOFs show extremely high stability, and SNNU-336 can maintain a stable structure even after 7 days in boiling water and 30 days in air, which is unprecedented for all Zn-based MOF materials. Different to common MOF adsorbents, the adsorption isotherms of SNNU-334–336 MOFs for C2H2 and CO2 under the same temperature all have an intersection point (we called the inverse point), which gradually moves to the high-pressure region with the increase of temperature and changes with the pore environment variation. So, SNNU-334–336 MOFs can be rationally controlled from C2H2-selective to CO2-selective CO2/C2H2 adsorption separation adsorbents. IAST selectivity calculation indicates that a very high CO2 over C2H2 selectivity (3595.4) can be achieved, which nearly surpasses those of all reported MOFs with CO2-preferred CO2/C2H2 separation performance. Fixed-bed column breakthrough experiments further prove that SNNU-334–336 MOFs all have controllable inverse CO2/C2H2 separation ability and can produce C2H2 with extra-high purity (>99.9%) from the CO2/C2H2 (1/99) mixture. [ABSTRACT FROM AUTHOR]

Al3+, Ga3+, In3+ and ligand 2,5-dihydroxyterephthalic acid (DHBDC) are used to construct the MIL-53 structure, which shows a sensing process based on the mechanism of excited state intramolecular proton transfer (ESIPT). The electron cloud density of the ligand in the framework is regulated by the metal, further adjusting the fluorescence sensing performance of the MOF. As the polarization of the metal weakens, the ligand-to-metal charge transfer ability weakens, the proton transfer ability of the DHBDC ligand increases, and the detection sensitivity increases. This rule was verified in the process of MIL-53-Al/Ga/In for N2H4 detection. The detection sensitivity and detection rate were ranked in the order MIL-53-In > MIL-53-Ga > MIL-53-Al. MIL-53-In was successfully applied to construct a high sensitivity, fast detection rate and reusable N2H4 sensor. This rule also laid the foundation for the construction of subsequent high-sensitivity fluorescence sensors. In addition, MIL-53-Al/Ga/In exhibits high-performance temperature sensing capabilities, which can achieve temperature sensing of 80–460 K. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) have attracted much attention for the oxygen evolution reaction (OER) in electrochemical water splitting. In this work, we use a two-dimensional (2D) MOF transformation strategy to synthesize FeNi layered double hydroxides (FeNi LDHs). 2D FeNi Hofmann MOFs ([Fe(L)2Ni(CN)4]) with a similar structure but different ligands (L = py, ISOQ) are synthesized as precursors. Accordingly, hydrolysis transformation assisted by NaBH4 leads to the growth of 2D FeNi-LDH nanosheets from 2D Hofmann-MOFs. During hydrolysis, OH− ions preferentially attack the coordination bond of [Fe(L)2Ni(CN)4], which allows FeNi-LDHs to form quickly on the surface of 2D MOFs. This rapid conversion process can effectively avoid the self-accumulation of LDHs. The hydrogen bubbles produced by NaBH4 can also inhibit the self-stacking of LDHs, which expose ample active species for the OER. Meanwhile, the synergistic effect between Fe and Ni contributes to the outstanding OER performance of FeNi-py-LDH, which shows an overpotential of 238 mV at 10 mA cm−2, a Tafel slope of 22 mV dec−1 and an excellent stability for 15 h. This work provides a universal synthesis method for ultra-thin FeNi-LDHs, which avoids the self-stacking of nanosheets and offers new insights into the OER. [ABSTRACT FROM AUTHOR]

The cathodic oxygen reduction reaction (ORR) is a key half-reaction for direct methanol fuel cells (DMFCs). Enhancing the electroactivity and selectivity of cathodic Pt-based ORR electrocatalysts is pivotal for accelerating the commercialization of DMFCs because of the scarcity of Pt metal and the inherent electroactivity of Pt-based electrocatalysts towards the methanol electrooxidation reaction. Herein, highly dispersed carbon nanobowl (CNBs) supported 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid (BmimBF4) functionalized Pt1Rh1 alloy nanocrystal nanohybrids (Pt1Rh1@BmimBF4/CNBs) are successfully synthesized by reducing mixed BmimBF4-PtII and BmimBF4-RhIII complex precipitates with NaBH4 solution. During the reduction process, PtRh alloy nanocrystals are simultaneously functionalized by BmimBF4 because of the strong N–metal interaction. Pt1Rh1@BmimBF4/CNBs nanohybrids with the optimal chemical composition reveal significantly enhanced ORR electroactivity and fascinating ORR selectivity (i.e., methanol tolerance) compared to Pt1Rh1/CNBs nanohybrids without BmimBF4 because of the carrier effect, alloy effect, and particular metal–organic interface. [ABSTRACT FROM AUTHOR]

High-quality CoP nanorings (CoP NRs) are easily achieved using a phosphorating treatment of CoOOH nanorings, and reveal high activity towards the hydrogen evolution reaction and the nitrate electrocatalytic reduction reaction due to substantial coordinately unsaturated active sites, a high surface area, and available mass transfer pathways. Consequently, the CoP NRs can achieve a faradaic efficiency of 97.1% towards NO3−-to-NH3 conversion and provide an NH3 yield of 30.1 mg h−1 mg−1cat at a −0.5 V potential. [ABSTRACT FROM AUTHOR]

A ligand exchange induced single crystal to single crystal (SCSC) transformation from 3D Hofmann-type frameworks [Fe(ep)M(CN)4] (ep = ethylpyrazine; M = Pt, Pd) to 2D layer networks [Fe(mp)2M(CN)4] (mp = methoxypyrazine) was observed. Interestingly, the different pillar–ligands showed a significant influence on the structural assembly and spin-crossover properties. [ABSTRACT FROM AUTHOR]

Holey CoOOH nanosheets (CoOOH HNSs) are easily synthesized by a successive coordination–oxidation–hydrolysis strategy. The CoOOH HNSs possess a large surface area, numerous pores, and substantial edge atoms with excellent electroactivity towards the oxygen evolution reaction in alkaline solution. The overpotential of 305 mV at 10 mA cm−2 for the CoOOH HNSs exceeds that of most monometallic Co-based electrocatalysts. [ABSTRACT FROM AUTHOR]

As an alternative pathway for present nitrogen fixation methods, the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions represents an attractive approach for sustainable and economic development of chemistry and biology. In this work, we synthesize bimetallic RhCu ultrathin nanoflake nanoaggregates (RhCu-BUNNs) with atomic thickness by a facile hydrothermal method. For the NRR, bimetallic RhCu-BUNNs exhibit better electrocatalytic activity than monometallic Rh ultrathin nanoflake nanoaggregates (Rh-UNNs) because the introduction of Cu can effectively weaken the competitive hydrogen evolution reaction (HER), which can achieve a high NH3 yield rate (95.06 μg h−1 mgcat−1) at −0.2 V potential. Density functional theory (DFT) calculations suggest that the introduction of Cu can effectively lower the energy demand in the *NN reductive process, resulting in NRR activity enhancement. Meanwhile, RhCu-BUNNs also show excellent electrocatalytic activity and selectivity for the glycerol oxidation reaction (GOR). For the electrochemical NH3 production, the sluggish anodic oxygen evolution reaction (OER) increases the overall electrolysis voltage. Herein, we replace the anodic OER with the GOR to assist the NRR using a bifunctional RhCu-BUNN electrocatalyst. Specifically, only 1.2 V whole voltage is required for electrochemical NH3 production in the presence of glycerol, accompanied by the generation of valuable glyceraldehyde at the anode. This work may provide a promising pathway to obtain both NH3 and valuable organic chemicals with high efficiency and low cost. [ABSTRACT FROM AUTHOR]

The development of active and durable non-precious metal based bifunctional electrocatalysts for overall water splitting is an urgent yet challenging task. In this work, we have successfully achieved iron doped cobalt phosphide ultrathin nanosheets (Fe-CoP UNSs) with a 2.3 nm thickness on a nickel foam (NF) substrate (termed Fe-CoP UNSs/NF) by high-temperature phosphidation treatment using atomically thick Fe doped cobalt oxide nanosheets as the reaction precursor. Because of the large surface area, sufficient edge active sites, synergistic effect between heteroatoms, high conductivity of the NF substrate, and porous structure of the NF substrate, Fe-CoP UNSs/NF displays outstanding electrocatalytic performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in a 1 M KOH electrolyte, such as overpotentials of 67 and 166 mV at current densities of 10 mA cm−2 and 50 mA cm−2, respectively. More importantly, Fe-CoP UNSs/NF can serve as a bifunctional electrocatalyst for overall water splitting, achieving a 10 mA cm−2 current density at a voltage of only 1.46 V in an alkaline electrolyte. [ABSTRACT FROM AUTHOR]

The controllable synthesis of highly stable porous metal–organic frameworks (MOFs) with targeted functions is urgently needed but still challenging up to now. In this work, we report the latest achievement in our continuous quest for robust 9-connected (9-c) MOFs based on [M3(O/OH)(COO)6(pyridine)3] building blocks. Different from the reported nets (ncb, xmz and pacs-MOFs) constructed from integrated or separated carboxylate and pyridine ligands, our metal–organic linker (MOL) strategy led to the discovery of six fascinating 9-c MOFs (SNNU-51–56) showing two types of completely new topological nets generated by cis, trans-coordination isomerism. As expected from highly connected architectures and the absence of open metal sites, all these MOFs show high thermal and moisture stability. They can even retain their frameworks after being treated at different pH values for 24 h. Furthermore, SNNU-51–56 not only inherit the excellent gas uptake performance of robust 9-c MOFs, but also exhibit extremely high CH4 separation from CO2, C2H2 and C2H4. Together with robust frameworks, the effective inner-cluster redox process in [M3(OH)(COO)6(pyridine)3] (M = Fe, Co and Ni) units makes SNNU-51–56 high-performance electrochemical pseudocapacitor materials. The asymmetric supercapacitor (ASC) fabricated with the SNNU-52 positive electrode and activated carbon (AC) negative electrode can be reversibly charged/discharged in a working voltage range of 0–1.6 V in 2 M KOH aqueous electrolyte for application in practical energy storage devices, and two serially connected ASCs can continuously light a light emitting diode. In all, greater control over the MOF structure, excellent thermal and chemical stability, and superb metal compatibility make [M3(O/OH)(COO)6(pyridine)3] clusters an ideal building block to design multifunctional MOF materials in the future. [ABSTRACT FROM AUTHOR]

Presented herein is a magnesium–organic framework (SNNU-88) incorporated with active hydroquinone groups, which exhibits not only remarkable semiconductor sensing for traces of ammonia vapor (5–100 ppm), but also extra-high fluorescence response to liquid NH3·H2O through an unusual turn-off (0–1.5 ppm) and turn-on (3.0–100 ppm) luminescence sensing mechanism at room temperature. Such bifunctional quantitative ammonia detection together with the extraordinary sensitivity and selectivity, fast response, and good reusability makes SNNU-88 one of the most powerful ammonia sensors. [ABSTRACT FROM AUTHOR]

A porous MOF platform (SNNU-65s) formed by creatively combining paddle-wheel-like [Cu2(COO)4] and trigonal prismatic [M3(μ3-O)(COO)6] building blocks was designed herein. The mixed and high-density open metal sites and the OH-functionalized pore surface promote SNNU-65s to exhibit ultra-high C2H2 uptake and separation performance. Impressively, SNNU-65-Cu-Ga stands out for the highest C2H2/CO2 (18.7) and C2H2/CH4 (120.6) selectivity among all the reported MOFs at room temperature. [ABSTRACT FROM AUTHOR]

The controllable synthesis of branched noble metal nanostructures has attracted significant attention as it provides excellent catalytic activity and durability to these metal nanostructures. In the present study, a facile and effective complexation–reduction strategy was developed for synthesizing Rh nanodendrites with hippocampus tail-like branches (Rh-NDHTs) using N2H4·H2O as a reductant and multiphosphonate molecule with small molecular weight as a complexant and functional agent. During the synthesis, the coordination interaction between multiphosphonate and RhCl3 as well as the hydrazine decomposition reaction (H2NNH2 = N2 + 2H2) catalyzed by the freshly formed Rh nanocrystals play important roles in the generation of Rh-NDHTs. Moreover, phosphonate functionalization of Rh-NDHTs was simultaneously achieved during the course of the synthesis, originating from the strong adsorption of multiphosphonate on the Rh surface. When used as a heterogeneous catalyst for the o-phenylenediamine oxidation reaction, the phosphonate-functionalized Rh-NDHTs exhibited enhanced catalytic efficiency and durability as compared to the commercially available Rh nanocrystals, attributing to their extraordinary morphological and interfacial properties. [ABSTRACT FROM AUTHOR]

Reported herein is the new application of ionothermal synthesis for inorganic optical materials. Under ionothermal conditions with different imidazolium ionic liquids, novel quaternary heterometallic frameworks based on [Pb4(OH)4] cubane and [CuCl4] or [CuBr4] chains and [Cu2I6] binuclear clusters have been successfully produced. Simple chlorine, bromine and iodine replacement leads to not only the space group change (tetragonal I41/acd for 1 and 2, and orthorhombic Fddd for 3) but also the topological net transformation (8,12-net for 1 and 2, and 6,6-net for 3). Notably, compounds 1, 2 and 3 all show tunable solid-state semiconducting and luminescence properties. [ABSTRACT FROM AUTHOR]

The synthetic design of new porous open-framework materials with pre-designed pore properties for desired applications such as gas adsorption and separation remains challenging. We proposed one such class of materials, rod metal–organic frameworks (rod MOFs), which can be tuned by using rod secondary building units (rod SBUs) with different geometrical and chemical features. Our approach takes advantage of the readily accessible metal–triazolate 1-D motifs as rod SBUs to combine with dicarboxylate ligands to prepare target rod MOFs. Herein we report three such metal–triazolate–dicarboxylate frameworks (SNNU-21, -22 and -23). During the formation of these three MOFs, Cd or Zn ions are firstly connected by 1,2,4-triazole through the N1,N2,N4-mode to form 1-D metal–organic ribbon-like rod SBUs, which further joint four adjacent rod SBUs via eight BDC linkers to give 3-D microporous frameworks. However, tuned by the different NH2 groups from metal–triazolate rod SBUs, different space groups, pore sizes and shapes are observed for SNNU-21–23. All of these rod MOFs show not only remarkable CO2 uptake capacity, but also high CO2 over CH4 and C2-hydrocarbons over CH4 selectivity under ambient conditions. Specially, SNNU-23 exhibits a very high isosteric heat of adsorption (Qst) for C2H2 (62.2 kJ mol−1), which outperforms the values of all MOF materials reported to date including the famous MOF-74-Co. [ABSTRACT FROM AUTHOR]

We report herein the synthesis of core–shell sandwich Au@polyallylamine@Pd nanostructures, in which the electronic structure of the Pd shell can be strongly tuned by the medial polyallylamine layers. The designed Au@polyallylamine@Pd nanostructures exhibit significantly improved electrocatalytic activity and stability for the formic acid oxidation reaction through the preferential dehydrogenation pathway. [ABSTRACT FROM AUTHOR]

The unusual 10-connected self-penetrating metal–organic framework based on sixteen-nuclear hybrid cadmium clusters has been constructed using 1,2,4-triazole, SCN−and F−as coligands, which represents the highest-connected uninodal network topology presently known for self-penetrating systems. [ABSTRACT FROM AUTHOR]

The first ionothermal case of the heterometallic iodoplumbate, [CuPb2I2Br(OH)2] (1), was prepared using 1-ethyl-3-methyl imidazolium bromide as a solvent. It exhibits an unprecedented (4,12)-connected topology with [Pb4(OH)4] cubane as the joint points of the helices. [ABSTRACT FROM AUTHOR]

A novel 3D (4,6)-connected topological architecture, obtained under ionothermal conditions by using 1-ethyl-3-methyl imidazolium bromide ([EMI]Br) as solvent and structure-directing agent, presents a non-centrosymmetric polar packing arrangement showing an interesting ferroelectric property. [ABSTRACT FROM AUTHOR]