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Ultrathin two‐dimensional (2D) metal‐organic nanosheets (MONs) have attracted continued attention in the field of advanced functional materials. Their nanoscale thickness, high surface‐to‐volume ratio, and abundant accessible active sites, are superior advantages compared with their 3D bulk counterparts. Bioinspired molecular scalpel strategy is a promising method for the creation of 2D MONs, and may solve the current shortcomings of MONs synthesis. This review aims to provide a state‐of‐the‐art overview of molecular scalpel strategies and share the results of current development to provide a better solution for MONs synthesis. Different types of molecular scalpel strategies have been systematically summarized. Both mechanisms, advantages and limitations of multiform molecular scalpel strategies have been discussed. Besides, the challenges to be overcome and the question to be solved are also introduced. [ABSTRACT FROM AUTHOR]

The preparation of ultra-small and well-dispersed metal nanoparticles (NPs) is of great importance for promoting oxygen reduction. Here, a metal (Fe and Zn) NP (7 nm) based catalyst derived from a Zn-based metal–organic framework was obtained by a vapor adsorption strategy, demonstrating a high half-wave potential (0.868 V) and power density (196 mW cm−2). [ABSTRACT FROM AUTHOR]

The production of metal–organic framework (MOF) nanoplates with well‐defined geometric morphology is remarkable for expanding their applications. Herein, the cobalt‐based MOF nanoplates with hexagonal channels from a layer‐pillared MOF are accomplished, via a molecular scalpel strategy, utilizing monodentate pyridine to replace the bidentate 4,4′‐bipyridine. The morphology can be modified from nanorods to nanoplates with controllable thickness tuned by the amounts of pyridine. Succeeding carbonization treatment transforms the MOF nanoplates into Co particles homogeneously encapsulated in the nitrogen‐doped carbon layers. The prepared catalyst with a unique platelike morphology displays a high half‐wave potential of 0.88 V in oxygen reduction reaction. When used in primary Zn−air batteries, it delivers a high peak power density of 280 mW cm−2. This work clarifies the structure‐morphology‐reactivity connection of MOF nanoplates. [ABSTRACT FROM AUTHOR]

For rechargeable Zn–air batteries, it is still a great challenge to design a safe and efficient bifunctional oxygen catalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this paper, an ultrasmall Ni3Fe alloy electrocatalyst embedded in nitrogen-doped carbon (denoted as Ni3Fe-NCNTs-800) was obtained by pyrolysis of Ni-MOF hybridized with ferrocene and assisted by melamine in an argon atmosphere at 800 °C. Metal–organic framework (MOF) precursors serve as cages to exert synergistic effects with melamine to limit the aggregation of metal particles, which is a promising strategy for the preparation of advanced oxygen catalysts. Ni3Fe-NCNTs-800 exhibits excellent electrochemical catalytic performance with an ORR (half-wave potential: 0.862 V) and OER (overpotential: 353 mV@10 mA cm−2) potential gap of 0.72 V. Density functional theory (DFT) calculations validate that the strong synergistic coupling of Ni3Fe bimetal plays a key role in lowering the reaction barrier and promoting the reversible oxygen reaction. In addition, liquid Zn–air batteries assembled with Ni3Fe-NCNTs-800 as the air cathode catalyst have ultra-high peak power density (211 mW cm−2 at 240 mA cm−2), specific battery capacity (806 mA h gZn−1), and robust cycle stability (no obvious decay after more than 1350 charge–discharge cycles), which are superior to commercial Pt/C + RuO2 based Zn–air batteries. And three all-solid-state ZABs connected in series can successfully light a LED (∼2.2 V), demonstrating their great potential in portable devices. [ABSTRACT FROM AUTHOR]

Rapid and accurate determination of biomarkers of human poisoning in real urine is of great significance for the assessment of health status. Herein, a luminescent urea-functionalized metal–organic framework (MOF), {[Cd(L)0.5(bpbix)]·x(solv)}n (1) (H4L = 5,5′-(((naphthalene-1,5-diylbis(azanediyl))bis(carbonyl))bis(azanediyl))diisophthalic acid; bpbix = 4,4′-bis((1H-imidazol-1-yl)methyl)biphenyl), has been successfully synthesized, and exhibits good stability in aqueous solutions in the normal urinary pH range and real urine. Complex 1 can serve as a dual-responsive luminescent biosensor for the detection of diphenyl phosphate (DPP) and hippuric acid (HA) as biomarkers of flame retardant triphenyl phosphate and toluene poisoning, and shows the advantages of high sensitivity, rapid response, good anti-interference capability, and reversibility. More significantly, complex 1 is successfully applied to the sensitive and accurate detection of DPP and HA in real urine with satisfactory recoveries. This work presents a dual-responsive luminescent MOF-based biosensor for simple, rapid, accurate, and reversible determination of urinary DPP and HA, which has promising application potential for the diagnosis of diseases related to triphenyl phosphate and toluene poisoning. [ABSTRACT FROM AUTHOR]

Zn–air batteries (ZABs) have attracted considerable attention due to the growing requirement for energy storage systems with high-energy density and safety. Meanwhile, the reasonable design of robust and cut-price bifunctional oxygen electrocatalysts is greatly desired for ZABs. Herein, a simple method to develop MOF (metal–organic framework)-derived hierarchical Fe,Co@N–C materials (FeCo–N–C-T), has been developed for effectively electrocatalyzing the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) based on ZnCo–ZIFs encapsulated with Fe-doped glucosamine (ZnCo–ZIF@Fe/glucosamine). Compared with commercial Pt/C and RuO2, the newly developed FeCo–N–C-700 exhibited superior electrocatalytic properties for the ORR (half-wave potential of 0.896 V) and OER (overpotential of 370 mV at 10 mA cm−2) and a reversible oxygen overpotential of 0.71 V. Simultaneously, it was demonstrated that the combination of Fe and Co showed synergistic improvements on the bifunctional activity. As a proof of concept, liquid- and solid-state Zn–air batteries (ZABs) were fabricated with FeCo–N–C-700 as air-cathodes. The developed liquid-ZABs exhibited an ultrahigh peak power density (150 mW cm−2 at 240 mA cm−2) and robust cycling stability (no obvious decay after more than 360 Please change to–discharging cycles), outperforming those based on commercial Pt/C + RuO2. As expected, all-solid-state ZABs based on FeCo–N–C-700 exhibited excellent reversibility and durability. In addition, density functional theory (DFT) investigations revealed that FeCoN8 was more active than Fe/CoN4 for the ORR and OER, indicating the synergetic effect of the Fe and Co active sites in FeCo–N–C-700 affording superior electrocatalytic performance. [ABSTRACT FROM AUTHOR]

As one of the most promising alternatives for future energy systems, the rechargeable Zn–air battery (ZAB) has attracted extensive attention due to its extraordinarily high theoretical specific energy density. However, several obstacles restrict its practical application. One challenge is the sluggish kinetics of oxygen-reduction reaction (ORR) and oxygen-evolution reaction (OER) in the discharging and charging processes of ZABs. In addition, when using unifunctional ORR or OER electrocatalysts as air electrodes, like noble metal catalysts (Pt/C or Ru/IrO2), there are the disadvantages of high cost and poor stability. Therefore, rational design of non-noble metal bifunctional ORR/OER electrocatalysts with high activity and stability is essential for the development of ZABs. In this review, we discuss the latest developments of non-noble metal bifunctional ORR/OER electrocatalysts for ZABs. Firstly, the related reaction mechanisms of ORR and OER are introduced. Then, the latest developments of bifunctional ORR/OER materials for ZABs are discussed in detail from three aspects: (i) MOF-based catalysts, including pristine MOFs and their derivatives; (ii) metal-free-based carbon catalysts, including heteroatom-doped carbon and defective carbon; (iii) metal-based catalysts, including metal–nitrogen–carbon materials (such as metals/alloys, single-atom) and metal compound materials. Finally, some challenges and outlooks for the optimal design of bifunctional air electrodes for rechargeable ZABs with high activity and ultra-long lifetime are put forward. [ABSTRACT FROM AUTHOR]

Rational design of non-noble metal-based bifunctional electrocatalysts for hydrogen evolution reactions (HER) and oxygen evolution reactions (OER) is still a challenge in water splitting. Herein, a MOF-on-MOF (MOF = metal-organic framework) strategy is developed to obtain trimetal-based nitrogen-doped carbon nanotubes arrays loaded on nickel foams (denoted as FeNiCo@NC/NF). Benefiting from the superior compositional and structural feature, FeNiCo@NC/NF self-supported electrodes exhibit excellent bifunctional HER and OER activity with a low overpotential of 145 and 245 mV at 10 mA cm−2. When simultaneously used as cathode and anode for water splitting, it only requires 1.61 V to achieve 10 mA cm−2 and even outperforms the benchmark electrode couple of Pt/C||RuO 2 at higher current densities. Studies discover that trimetallic FeNiCo nanoparticles can provide more synergetic metal active sites, interconnected N-doped carbon nanotubes arrays can offer more effective electron transports channels, and conductive Ni foam substrate can reduce the internal impedance of the material. Density functional theory (DFT) calculations also demonstrate that FeNiCo@NC/NF electrode possesses a favorable Gibbs free energy of hydrogen adsorption (ΔG H*) value of −0.13 eV, which is benefit for its superior HER activity. Overall, our work reports an efficient self-supported electrode for hydrogen/oxygen evolution reactions and water splitting. • Synergistic effect among trimetals and N-dopants enhances HER/OER activities. • N-CNTs could offer more effective electron transports channels. • Hierarchical structure ensures super-fast evolution and escape of H 2 and O 2. • Without polymer binder reduces the internal impedance of the material. • ΔG H* = −0.13 eV further manifests their superior HER activity. [ABSTRACT FROM AUTHOR]

The rational design of advanced oxygen reduction reaction (ORR) catalysts is essential to improve the performance of energy conversion devices. However, it remains a huge challenge to construct hierarchical micro-/meso-/macroporous nanostructures, especially mesoporous transport channels in catalysts, to enhance catalytic capability. Herein, motivated by the characteristics of energetic metal-organic frameworks (EMOFs) that produce an abundance of gases during high-temperature pyrolysis, we prepared a unique tetrazine-based EMOF-derived electrocatalyst (denoted as Fe 3 C@NSC-900) consisting of highly dispersed Fe 3 C nanoparticles and N,S-codoped mesoporous carbon nanotubes. The mesopore-dominated core-shell structure endows Fe 3 C@NSC-900 with excellent catalytic activity and efficient mass transfer. Thus, optimal Fe 3 C@NSC-900 demonstrates a high half-wave potential of 0.922 V and great stability in 0.1 M KOH, outperforming commercial Pt/C and most of the reported ORR catalysts. As far as we know, this work is the first application of a tetrazine-based EMOF derivative for the electrocatalytic ORR and is expected to offer some constructive insights into potential of EMOFs for new-generation catalyst design.