NIR-switchable local hydrogen generation by tandem bimetallic MOFs nanocomposites for enhanced chemodynamic therapy

The inadequate quantity of hydrogen peroxide(H_(2)O_(2))in cancer cells promptly results in the constrained success of chemodynamic therapy(CDT).Significant efforts made throughout the years;nevertheless,researchers are still facing the great challenge of designing a CDT agent and securing H_(2)O_(2) supply within the tumor cell.In this study,taking advantage of H_(2)O_(2) level maintenance mechanism in cancer cells,a nanozyme-based bimetallic metal-organic frameworks(MOFs)tandem reactor is fabricated to elevate intracellular H_(2)O_(2) levels,thereby enhancing CDT.In addition,under nearinfrared excitation,the upconversion nanoparticles(UCNPs)loaded into the MOFs can perform photocatalysis and generate hydrogen,which increases cellular susceptibility to radicals induced from H_(2)O_(2),inhibits cancer cell energy,causes DNA damages and induces tumor cell apoptosis,thus improving CDT therapeutic efficacy synergistically.The proposed nanozyme-based bimetallic MOFs-mediated CDT and UCNPs-mediated hydrogen therapy act as combined therapy with high efficacy and low toxicity.

An intermittent lithium deposition model based on CuMnbimetallic MOF derivatives for composite lithium anode with ultrahigh areal capacity and current densities

Recently,three-dimensional(3D)conductive frameworks have been chosen as the host for composite lithium(Li)metal anode because of their exceptional electrical conductivity and remarkable thermal and electrochemical stability.However,Li tends to accumulate on the top of the 3D frameworks with homogenous lithiophilicity and Li dendrite still growth.This work firstly designed a bimetallic metal-organic framework(MOF)(CuMn-MOF)derived Cu_(2)O and Mn_(3)O_(4) nanoparticles decorated carbon cloth(CC)substrates(CC@Cu_(2)O/Mn_(3)O_(4))to fabricate a composite Li anode.Thanks to the synergistic effects of lithiophilic Cu_(2)O and Mn_(3)O_(4),the CC@Cu_(2)O/Mn_(3)O_(4)@Li symmetrical cell can afford a prolonged cycling lifespan(1400 h)under an ultrahigh current density and areal capacity(6 mA·cm^(-2)/6 mAh·cm^(-2)).When coupled with the LiFePO_(4)(LFP)cathode,the LFP||CC@Cu_(2)O/Mn_(3)O_(4)@Li full cell demonstrated a superior performance of 89.7 mAh·g^(-1) even at an extremely high current density(10 C).Furthermore,it can also be matched well with LiNi_(0.5)Co^(0).2Mn_(0.3)O_(2)(NCM523)cathode.Importantly,to explain the excellent performances of the CC@Cu_(2)O/Mn_(3)O_(4)@Li composite anode,an intermittent model was also proposed.This study offers a novel model that can enhance our comprehension of the Li deposition behavior and pave the way to attain stable and safe Li metal anodes by employing bimetallic MOF-derived materials to construct 3D frameworks.

An Fe-N/S-C hybrid electrocatalyst derived from bimetal-organic framework for efficiently electrocatalyzing oxygen reduction reaction in acidic media

Heteroatoms doped Fe-N-C electrocatalysts have been widely acknowledged as one of the most promising candidates to replace Pt-based materials for electrocatalyzing oxygen reduction reaction(ORR).However,the complicated synthesis method and controversial catalytic mechanism represent a substantial impediment as of today.Herein,a very facile strategy to prepare Fe-N/S-C hybrid through pyrolyzing Zn and Fe bimetallic MOFs is rationally designed.The electrocatalytic ORR performance shows a volcanotype curve with the increment of added Fe content.The half-wave potential(E1/2) for ORR at optimized Fe-N/S-C-10%(10%=n(Fe)/(n(Fe)+n(Zn)),n(Fe) and n(Zn) represent the moles of Fe2+ and Zn2+ in the precursors,respectively) shifts significantly to the positive direction of 19.6 mV with respect to that of Pt/C in acidic media,as well as a high 4 e selectivity and methanol tolerance.After 10,000 potential cycles,E1/2 exhibits a small negative shift of-27.5 mV at Fe-N/S-C-10% compared favorably with Pt/C(~141.0 mV).This can be attributed to:(ⅰ) large specific surface area(849 m^(2)/g) and hierarchically porous structure are favorable for the rapid mass transfer and active sites exposure;(ⅱ) the embedded Fecontaining nanoparticles in porous carbon are difficult to be moved and further agglomerated during the electrochemical accelerated aging test,further improving its stability;(ⅲ) there exist small Fecontaining nanoparticles,uniformly doped N and S,abundant Fe-N as efficiently active sites.This work represents a breakthrough in the development of high-efficient non-precious-metal catalysts(NPMCs)to address the current Pt-based electrocatalysts challenges.

Heterojunction between bimetallic metal-organic framework and TiO_(2):Band-structure engineering for effective photoelectrochemical water splitting

Bimetallic Fe/Ni-based metal-organic frameworks(MOFs)with different Fe/Ni ratios were coated on TiO_(2)nanorods(NRs),and the performances of the heterojunction photoanodes in photoelectrochemical water splitting were investigated.The bandgaps and band positions of the MOFs could be modulated by changing the ratio of the Fe and Ni components.An ideal band alignment was achieved between the TiO_(2)NRs and bimetallic MOFs with an optimum ratio of[Fe]/[Ni]=0.25/0.75,which allowed efficient light absorption and charge separation.The coating of NH_(2)-MIL(Fe)-88 layer on the TiO_(2)NRs decreased the photocurrent density by 33%.In comparison,TiO_(2)/NH_(2)-MIL(Ni)-88 showed a modest improvement in photocurrent density(0.85 mA·cm^(−2)at 1.23 V vs.a reversible hydrogen electrode(RHE)).When bimetallic NH_(2)-MIL(Fe_(0.25)Ni_(0.75))-88 was coated on the TiO_(2)NRs,the photocurrent density reached 1.56 mA·cm^(−2),which was an efficiency enhancement of 3.2 times.The mechanism underlying high photoelectrochemical performance was investigated.

MOF-derived Porous Carbon Nanofiber Assembly as High Efficiency ORR Electrocatalysts for Zinc-air Batteries

Reasonable construction of high activity and low cost non-noble metal oxygen reduction reaction(ORR)catalyst is of great importance for the wide application of zinc-air batteries(ZABs).Using bimetallic MOF as a precursor combined with electrospinning,high-temperature carbonization and electrodeposition,we successfully developed a porous carbon nanofiber(Co@Fe-CNFs-1000)with bimetallic active center as an efficient catalyst for ORR.The successful construction of this special core-shell structure directly explores the synergy between different active centers.The results showed that the synthesized Co@Fe-CNFs-1000 catalyst exhibited ORR performance comparable to that of Pt/C in 0.1 mol/L KOH electrolyte,high half-wave potential(E_(1/2)=0.81 V)and limiting current density(J_(L)=5.4 mA·cm^(-2)).In addition,homemade liquid ZABs with Co@Fe-CNFs-1000 as the air cathode showed excellent power density(155.8 mW·cm^(-2)),specific capacity(780.6 mAh·g_(Zn)^(-1))and long-term stability(over 100 h at 2 mA·cm^(-2)),surpassing even Pt/C-based batteries.In addition,the flexible solid-state ZABs assembled based on Co@Fe-CNFs-1000 demonstrates excellent flexibility and durability.This work provides a new idea for constructing ORR catalysts with high activity centers.

Ultrathin two-dimensional bimetal NiCo-based MOF nanosheets as ultralight interlayer in lithium-sulfur batteries

Lithium-sulfur batteries as one of the most promising next-generation high-energy storage system, the shuttle effect, the expansion of cathode and the slow electrode redox kinetics limit its further development. Herein, we report a two-dimensional, ultrathin and ultra-light bimetal-Ni Co-organic framework as the interlayer for Li-S batteries. This kind of interlayer can effectively block polysulfides and accelerate the conversion with a thickness of only 1 μm and a load of 0.1 mg/cm^(2). Because the MOF nanosheets with a thickness of a few nanometers have a large specific surface and a large number of exposed accessible active sites. At the same time, the intrinsic activity of each site is enhanced and the catalytic performance is improved due to the synergistic effect of mixed metals and the unique coordination environment around the active sites. So, 2D NiCo MOF/CNT totally meets the requirements for the lightweight and effective interlayer. The initial discharge capacity of cell with 2D NiCo MOF/CNT interlayer can reach 1132.7 m Ah/g at 0.5 C. It remained 709.1 m Ah/g after 300 cycles, showing good cycling stability and rate performance.

Mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes synthesized in deep eutectic solvent and their catalytic performances

To develop high-performance metal-organic frameworks(MOFs)for catalysis is of great importance.Here,we synthesized the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)(BTC=benzene-1,3,5-tricarboxylate)nanocubes in a deep eutectic solvent of ZnCl_(2)/ethylene glycol solution.The route can proceed at room temperature and the reaction time needed is shortened to be 30 min,which is superior to the conventional solvothermal route that usually needs high temperature and long reaction time.The formation mechanism of the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes in deep eutectic solvent(DES)was investigated by in situ synchrotron X-ray diffraction/small angle X-ray scattering/X-ray absorption fine structure conjunction technique.The mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes exhibit high catalytic activity and reusability for cyanosilylation reaction of benzaldehyde and aerobic oxidation reaction of benzylic alcohol.

Preparation of metal‐organic frameworks and their derivatives for supercapacitors

To satisfy the requirements of social power development,it is urgently necessary to develop innovative and sustainable new energy storage devices.Supercapacitors have attracted considerable attention as a new type of energy storage device,owing to their high energy density,high power density,fast charging and discharging speeds,and long cycle life.The electrode material is an important factor in determining the electrochemical performance of supercapacitors.In recent years,researchers explored the application of metal‐organic frameworks(MOFs)and their derivatives as electrode materials for supercapacitors.In this paper,the preparation of monometallic,bimetallic,and conductive MOFs,and their derivatives for application in supercapacitors are reviewed.In addition,challenges facing MOFs in the field of supercapacitors and their future development prospects are discussed.

Chelating Metal Ions in a Metal-Organic Framework for Constructing a Biomimetic Catalyst Through Post-modification

Crystal engineering,as a burgeoning technology,has been widely used to construct metalloporphyrins biomimetic catalysts.Herein,a bimetallic metal-organic framework(MOF)was constructed by 4-(4-carboxyphenyl)-1,2,4-triazole ligand,Co2+and Zr4+metal ions by solvothermal reaction(named PFC-88).A N,N-chelation site was found between the two adjacent ligands in PFC-88,consequently a porphyrin-like structure was obtained through chelating Fe^(3+) in this site by post-modification,named PFC-88-Fe.The result of a single crystal X-ray technology verified that Fe ions were successfully metalated in the N,N-chelation site of PFC-88,which is assisted by the X-ray absorption near-edge structure(XANES)spectra.An o-phenylenediamine oxidation reaction was applied to assessing the catalytic activity of PFC-88-Fe,in which the absorbance increases of phenazine-2,3-diamine atλ=418 nm were recorded by absorption spectroscopy in kinetic mode,exhibiting the application potential as a biomimetic catalyst.