Ni-based Metal-organic Framework Research Articles

In-situ restructuring of Ni-based metal organic frameworks for photocatalytic CO2 hydrogenation

As the global quest for sustainable energy keeps rising, exploring novel efficient and practical photocatalysts remains a research and industrial urge. Particularly, metal organic frameworks were proven to contribute to various stages of the carbon cycle, from CO2 capture to its conversion. Herein, we report the photo-methanation activity of three isostructural, nickel-based metal organic frameworks incorporating additional niobium, iron, and aluminum sites, having demonstrated exceptional CO2 capture abilities from thin air in previous reports. The niobium version exhibits the highest performance, with a CO2 to CH4 conversion rate in the order of 750–7500 µmol*gcatalyst−1*h−1 between 180 °C and 240 °C, achieving 97% selectivity under light irradiation and atmospheric pressure. The in-depth characterization of this framework before and after catalysis reveals the occurrence of an in-situ restructuring process, whereas active surface species are formed under photocatalytic conditions, thus providing comprehensive structure-performance correlations for the development of efficient CO2 conversion photocatalysts.

A Lewis basic site rich metal-organic framework featuring a hydrogen-bonded acetylene nano-trap for the efficient separation of C2H2/CO2.

The physical separation of C2H2 from CO2 on metal-organic frameworks (MOFs) has received a substantial amount of research interest due to its advantages of simplicity, security, and energy efficiency. However, the exploitation of ideal MOF adsorbents for C2H2/CO2 separation remains a challenging task due to their similar physical properties and molecular sizes. Herein, we report a unique C2H2 nano-trap constructed using accessible oxygen and nitrogen sites, which exhibits energetic favorability toward C2H2 molecules. This material exhibits a good acetylene capacity of 55.31 cm3 g-1 and high C2H2/CO2 selectivity of 7.0 under ambient conditions. We have combined in situ IR spectroscopy and in-depth theoretical calculations to unravel the synergistic interactions driven by the high density of accessible oxygen and nitrogen sites. Furthermore, dynamic breakthrough experiments confirmed the capability of TUTJ-201Ni for the separation of binary C2H2/CO2 mixtures. This study on Ni-based MOFs will enrich Lewis basic site rich MOFs for gas adsorption and separation applications.

A Highly Stable Electrochemical Sensor Based on a Metal-Organic Framework/Reduced Graphene Oxide Composite for Monitoring the Ammonium in Sweat.

The demand for non-invasive, real-time health monitoring has driven advancements in wearable sensors for tracking biomarkers in sweat. Ammonium ions (NH4+) in sweat serve as indicators of metabolic function, muscle fatigue, and kidney health. Although current ion-selective all-solid-state printed sensors based on nanocomposites typically exhibit good sensitivity (~50 mV/log [NH4+]), low detection limits (LOD ranging from 10-6 to 10-7 M), and wide linearity ranges (from 10-5 to 10-1 M), few have reported the stability test results necessary for their integration into commercial products for future practical applications. This study presents a highly stable, wearable electrochemical sensor based on a composite of metal-organic frameworks (MOFs) and reduced graphene oxide (rGO) for monitoring NH4+ in sweat. The synergistic properties of Ni-based MOFs and rGO enhance the sensor's electrochemical performance by improving charge transfer rates and expanding the electroactive surface area. The MOF/rGO sensor demonstrates high sensitivity, with a Nernstian response of 59.2 ± 1.5 mV/log [NH4+], an LOD of 10-6.37 M, and a linearity range of 10-6 to 10-1 M. Additionally, the hydrophobic nature of the MOF/rGO composite prevents water layer formation at the sensing interface, thereby enhancing long-term stability, while its high double-layer capacitance minimizes potential drift (7.2 µV/s (i = ±1 nA)) in short-term measurements. Extensive testing verified the sensor's exceptional stability, maintaining consistent performance and stable responses across varying NH4+ concentrations over 7 days under ambient conditions. On-body tests further confirmed the sensor's suitability for the continuous monitoring of NH4+ levels during physical activities. Further investigations are required to fully elucidate the impact of interference from other sweat components (such as K+, Na+, Ca2+, etc.) and the influence of environmental factors (including the subject's physical activity, posture, etc.). With a clearer understanding of these factors, the sensor has the potential to emerge as a promising tool for wearable health monitoring applications.

Synergistic Inclusion of Reaction Activator and Reaction Accelerator to Ni-MOF Toward Extra-Ordinary Performance of Urea Oxidation Reaction.

Recently electrochemical urea oxidation reaction (UOR) has emerged as the technology of demand for commercialization of urea-based energy conversion. However, the nascent idea is limited by the energy burden of threshold voltage and the sluggish reaction kinetics involving a six-electron transfer mechanism. Herein, for the first time, the engineering of electrocatalysts are proposed with simultaneous inclusion of UOR activator and UOR accelerator. Nitrogen-doped carbon-decorated Ni-based Metal Organic Framework (MOF)has been synthesized as the base catalyst material. MoO2 and rGO with varied loading have been attached to the MOF to get the desired MoO2/Ni-MOF/rGO heterostructure incorporating defects and crystal strain within the materials. Investigations reveal that the invoked lattice strain and atomic defects promote plenteous Ni3+ active sites. The optimized sample demonstrates extraordinary performance of UOR having the potential value as low as 1.32V versus RHE to reach the current density of 10mAcm-2 and the tafel slope is only 31mVdec-1 reflecting very fast reaction kinetics. Here MoO2 plays the role of UOR activator whereas optimized loading of rGO proliferates the reaction speed. This work, experimentally and theoretically, presents a new insight to enhance electrocatalytic urea oxidation reaction opening an avenue of urea-based energy-harvesting technology.

Ligand modulated charge transfers in Z-scheme configured Ni-MOF/g-C3N4 nanocomposites for photocatalytic remediation of dye-polluted water

The development of photocatalysts must be meticulous, especially when they are designed to degrade hazardous dyes that cause mutagenesis and carcinogenesis. In this meticulous approach, Ni-based metal–organic frameworks with different ligands, including terephthalic acid (NTP), 2-aminoterephthalic acid (NATP), and their composite with g-C3N4 (NTP/GCN, and NATP/GCN) have been synthesized using hydrothermal method. Structural analysis by XRD and ATR-IR revealed synergistic properties due to robust chemical interactions between the NATP-MOFs and GCN systems. A flower-like morphology was observed for both NTP and NATP, while their composites showed mixed-particulate structures mimicking the morphology of GCN. Optical analyses indicated visible-light driven properties with modulated recombination resistance in the system. Among the synthesized bare and composite systems, NATP/GCN exhibited the highest photocatalytic degradation efficiency for the cationic rhodamine B dye (~ 93% in 120 min), while it was relatively less efficient for the anionic Congo red dye, (~ 64% in 120 min). The insights gained from the fundamental characterizations including Mott–Schottky, scavenger, and electrochemical impedance analysis revealed that the amino-groups in NATP/GCN composite offered the band edge potentials suitable for the effective generation of energetic radical species with the improved carrier delocalization, recombination resistance, and charge transfer properties in the composite system through Z-scheme formation. Parametric investigations by varying the concentration of catalyst, dye, and pH along with recycle studies, demonstrated the excellent stability of the developed composites for sustainable photocatalytic applications.

Spherical NiS2/Ni17S18–C accelerates ion transport and enhances kinetics for lithium-sulfur battery host material

Transition metal sulfides exhibit notable catalytic activity and possess a high theoretical specific capacity as host materials in lithium-sulfur batteries. However, their restricted conductivity and sluggish Li+ transport hinder their broader application. In this research, we developed a Ni-based metal-organic framework (Ni-MOF) using nitrogen-containing benzimidazole and coupled it with a highly conductive carbon nanotube (CNT) to form NixSy (NiS2–Ni17S18)–C/CNT. The N-doped carbon skeleton derived from the MOF enhances the adsorption and chemical anchoring of polysulfides, while the even distribution of NiS2 and Ni17S18 enhances the redox reaction kinetics. Additionally, the conductive CNT networks aid in rapid electron transport, resulting in improved sulfur utilization. Consequently, the NixSy-C/CNT@S electrode demonstrates an impressive initial specific capacity of 1468 mAh g−1 at 0.2C and maintains 904.4 mAh g−1 after 200 cycles. Moreover, NixSy-C/CNT@S displays exceptional cycle stability, with a capacity retention of 76.20 % and a decay rate of only 0.05 % per cycle after 500 cycles at 0.5C. This study paves the way for the development and synthesis of cathode materials with outstanding electrochemical performance in LSBs.

Alkali-Stable Metal-Organic Frameworks with Enhanced Electroconductivity for Black-Brown Electrochromic Energy Storage Smart Window.

Metal-organic frameworks (MOFs) deliver potential applications in electrochromism and energy storage. However, the poor intrinsic conductivity of MOFs in electrolytes seriously hampers the development of the above-mentioned electrochemical applications, especially in one MOF electrode. Herein, a new Ni-based MOF (denoted Ni-DPNDI) is proposed with enhanced conductivity by π-delocalized DPNDI connectors. Predictably, the obtained Ni-DPNDI MOF achieves a conductivity of up to 4.63 S∙m-1 at 300 K. Profiting from its unique electronic structure, the Ni-DPNDI MOF delivers excellent electrochromic and energy storage performance with a great optical modulation (60.8%), a fast switching speed (tc = 7.9 s and tb = 6.4 s), a moderate specific capacitance (25.3 mAh·g-1) and good cycle stability over 2000 times. Meanwhile, energy storage capacity is visual by the coloration states of Ni-DPNDI film. As a proof of the potential application, a large-area (100 cm2) electrochromic energy storage smart window is further designed and displayed. The strategy provides an interesting alternative to porous multifunctional materials for the new generation of electronic devices with diverse applications.

Multifunctional Ni-MOF (3D) with N-rich structures for self-generated reactive oxygen species and enhanced electron transfer for synergistic degradation of organic pollutants and removal of Hg(II)

Metal–organic frameworks (MOFs) can effectively adsorb or remove pollutants; however, their application to water treatment remains limited. Herein, we report the preparation of two novel multifunctional Ni-based MOFs (2D and 3D), via the design and synthesis of multi-nitrogen-like ligands. The introduction of polynitrogen-containing organic macrocyclic ligands improved the structure and electron transfer capability of the MOF, and its adsorption and synergistic degradation performance were further enhanced via coordination with Ni. The 3D MOF (MOF-2) had a maximum adsorption capacity of 948 mg/g for Hg(II). The adsorption and synergistic degradation capacities of MOF-2 for tetracycline (TC, 18 mg/L), 17α-ethynylestradiol (EE2, 3 mg/L), rhodamine B (RhB, 6 mg/L), and methylene blue (MB, 6 mg/L) were 98.54%, 97.32%, 91.08%, and 85.02%, respectively. The addition of KHSO5 (PMS, 0.01 g/L) resulted in nearly 100% degradation of the organic pollutants within 100 min. MOF-2 alone simultaneously degraded more than 90.73% (360 min Hg(II) adsorption equilibrium) of five pollutants in ultrapure water, tap water, and lake water. MOF-2+PMS degraded 99.13% of TC within 60 min, and the remaining four pollutants were completely adsorbed and degraded. DFT calculations and experiments indicated that the efficient adsorption of Hg(II) and efficient degradation of the organic pollutants by MOF-2 were mainly attributed to its abundant N atoms, which provide active sites for Hg(II) capture; and the structure itself has strong electron transfer ability and self-produced reactive oxygen species (ROS), which can effectively degrade organic pollutants and activate PMS to enhance the degradation efficiency. MOF-2 also exhibited 100% antibacterial activity against Escherichia coli and Staphylococcus aureus. This work provides a basis for designing synthesis pathways for MOFs and elucidates the electron-transfer mechanism underlying the enhanced synergistic removal of complex pollutants from water.

Unraveling the Potential Dependence of Active Structures and Reaction Mechanism of Ni-based MOFs Electrocatalysts for Alkaline OER.

Nickel-based metal-organic frameworks (MOFs) with flexible structure units provide a broad platform for designing highly efficient electrocatalysts, especially for alkaline oxygen evolution reaction (OER). However, the stability of MOFs under harsh and dynamic reaction conditions poses significant challenges, resulting in ambiguous structure-activity relationships in MOFs-based OER research. Herein, Ni-benzenedicarboxylic acid-based MOF (NiBDC) is selected as prototypical catalyst to elucidate its real active sites for OER and reaction pathway under different reaction states. Electrochemical measurements combined with X-ray absorption spectroscopy (XAS) and Raman spectroscopy reveal that the complete reconstruction of NiBDC to β-NiOOH in the chronoamperometry activation process is responsible for significantly increased OER performance. In situ XAS and Raman results further demonstrate the electro-oxidation of β-NiOOH into γ-NiOOH at high-potential state (above 1.6V vs RHE). Furthermore, the collective evidences from key reaction intermediates and isotope-labeled products definitely unravel the potential dependence of OER mechanism: OER process at low-potential state proceeds mainly through the lattice oxygen-mediated mechanism, while adsorbate evolution mechanism emerges as the predominant pathway at high-potential state. Interestingly, the dynamically changing OER mechanism can not only reduce the required overpotential at the low-potential state but also improve the electrochemical stability of catalysts at high-potential state.

Upgrading Structural Conjugation in Three-Dimensional Ni-Based Metal-Organic Frameworks for Promoting Electrical Conductivity and Specific Capacitance.

Metal-organic frameworks (MOFs) have emerged as promising candidates for electrochemical energy storage and conversion due to their high specific surface areas, abundant active sites, and excellent chemical and structural tunability. However, the direct utilization of MOFs as electrochemical materials is a challenge because of the poor electroconductivity induced by the insulating nature of most organic linkers. Herein, a conjugated three-dimensional Ni-MOF {Ni(HBTC)(BPE)}n (Ni-BPE) with a 2-fold interpenetrating structure was developed via the coordination polymerization of Ni2+, a H3BTC ligand (1,3,5-benzenetricarboxylic acid), and a vinyl-functionalized bipyridine linker (1,2-di(4-pyridyl)ethylene, BPE). Ni-BPE displayed an enhanced conjugation system compared to analogous and insulated Ni-BPY that is constructed by the Ni-BTC layer and ordinary bipyridine linker (4,4'-bipyridine, BPY). Notably, upgrading structural conjugation promoted a dramatical ∼204 times increase in the electroconductivity of Ni-BPE compared to Ni-BPY. More importantly, Ni-BPE displayed a higher specific capacitance of 633.2 F g-1 (316.6 C g-1) at 1 A g-1, which exhibited a significant ∼1.5-fold enhancement than Ni-BPY. Furthermore, the asymmetric supercapacitor can reach a good energy density of 25.2 Wh kg-1 with a reasonable cycle stability of 71.0% over 5000 cycles. This work provides an effective method for optimizing the structure of insulating MOFs to enhance the electroconductivity and specific capacitance.

Equimolar CO2 adsorption by two Ni-based MOFs and their kinetic and thermodynamic studies

Metal-organic frameworks (MOFs) show great potential in CO2 capture due to their unique structure. This study investigated two Ni-based MOFs, Ni-MOF-74 and IR-MOF-74, with different organic ligand chain lengths. The optimal activation temperatures for each material were determined, resulting in high CO2 adsorption capacities (1.9401 and 1.9475 mmol/g at 30 °C and 0.16 bar, respectively). The adsorption capacities of the two materials were found to reach the equimolar adsorption by the fitting calculation. The adsorption process of Ni-MOF-74 and IR-MOF-74 were found to follow a pseudo-first-order kinetic model. Thermodynamic analysis revealed an entropy-enthalpy complementarity between Ni-MOF-74 and IR-MOF-74 during CO2 capture. Notably, optimal adsorption and desorption temperatures were determined for these materials, a first in the field of porous solid adsorbents. Finally, the materials demonstrated stable adsorption capacity over 10 cycles.

Folic acid-assisted in situ solvothermal synthesis of Ni-MOF/MXene composite for high-performance supercapacitors

The synthesis of Ni-based metal-organic framework (MOF) and Ti3C2Tx MXene nanosheets is achieved via a straightforward solvothermal method, resulting in the formation of Ni-MOF/MXene composite material. This study introduces an innovative strategy that employs the biomolecule folic acid for the solvothermal synthesis of Ni-MOF/MXene nanosheets, intending to achieve high-performance supercapacitors. This approach effectively prevents the oxidation and restacking of MXene nanosheets and ensures the uniform dispersion of Ni-MOF on the surface of MXene nanosheets. The Ni-MOF/MXene composite exhibits an outstanding specific capacitance of 716.19 F/g at 1 A/g current density. Furthermore, an asymmetric supercapacitor device was assembled using activated carbon and Ni-MOF/MXene composite as negative and positive electrodes, respectively. The asymmetric device exhibited an impressive energy density of 23.28 Wh/kg at a power density of 2.841 KW/kg, along with good cyclic stability. These results establish an excellent potential of the Ni-MOF/MXene composite material as a candidate for next-generation energy devices.

Synthesis and characterization of nickel-based MOFs: Enhancing photocatalysis and targeted cancer drug delivery

Metal–organic frameworks (MOFs) are intricate molecular solids formed by connecting organic ligands with metal or metal–cluster binding sites. They have exceptional characteristics such as expansive surface area, adaptability, and meticulously structured porosity, rendering them valuable in various applications including photocatalytic degradation and drug delivery systems. In this investigation, a benign Ni-based MOF was synthesized using benzene 1,4dicarboxylic acid as a linker and dimethyl sulfoxide as a solvent through the hydrothermal approach within a Teflon autoclave. The synthesized MOFs were precisely characterized using techniques such as X-ray diffraction, scanning electron microscope with energy-dispersive X-ray analysis, Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis, and N2-sorption measurements. The photocatalytic efficiency of the Ni-based MOF was explored against Congo red under visible light exposure, with the proposed mechanism involving electron transfer from photoexcited organic ligands to metallic clusters, resulting in a degradation efficiency of 98.68 % after 145 min. Furthermore, the Ni-based MOFs, when loaded with the anticancer drug cisplatin, displayed notable capabilities in drug delivery against the human breast cancer cell line MDA-MB-231, leading to a 35.26 % reduction in cell viability. Cytotoxicity assessments using the MTT assay revealed that the nano-carriers hindered cell proliferation with an IC50 value of 46.84 μg/mL.

Fabrication Methods of Continuous Pure Metal-Organic Framework Membranes and Films: A Review.

Metal-organic frameworks (MOFs) have drawn intensive attention as a class of highly porous, crystalline materials with significant potential in various applications due to their tunable porosity, large internal surface areas, and high crystallinity. This paper comprehensively reviews the fabrication methods of pure MOF membranes and films, including in situ solvothermal synthesis, secondary growth, electrochemical deposition, counter diffusion growth, liquid phase epitaxy and solvent-free synthesis in the category of different MOF families with specific metal species, including Zn-based, Cu-based, Zr-based, Al-based, Ni-based, and Ti-based MOFs.

Strong electronic coupling between Ni-based MOF and Ni2P enables high-efficiency oxygen evolution reaction for various application scenarios

The high overpotential and sluggish kinetics of oxygen evolution reaction (OER) severely hinder the widespread application of electrochemical water splitting, especially at industrial-level current densities. Herein, we report a novel heterostructural Ni-based metal organic framework (MOF)-Ni2P in-situ grown on iron foam (NiMOF-Ni2P/IF), which shows remarkable OER activity and stability. We demonstrate that the work function difference between NiMOF and Ni2P leads to the strong electron coupling effect by promoting electron transfer at the interface and results in a discernible upward shift of the d-band center of Ni sites for favorable OH− adsorption. The as-fabricated NiMOF-Ni2P/IF exhibits an ultralow overpotential of 330 mV and a small cell voltage of 1.796 V to drive NiMOF-Ni2P/IF‖Pt/C system at 1000 mA cm−2 in 1 M KOH, outperforming the majority of state-of-the-art non-noble-metal-based electrocatalysts. Furthermore, the catalyst shows remarkable performance even under harsh industrial conditions of 40, 60, and 80 °C in 6 M KOH. In addition, NiMOF-Ni2P/IF holds great promise with remarkable stability of 200 h and 600 cycles in simulated seawater and secondary zinc-air batteries (ZABs), respectively. This work offers a rational design strategy for low cost, high activity, and long durability OER electrocatalyst based on in-depth comprehension of the electronic coupling effect.

Regulation of eg orbital occupancy in Ni-based metal-organic frameworks for efficient hydrogen peroxide electrosynthesis

Subject to the binding strength between the cathode and the oxo-intermediates, the hydrogen peroxide (H2O2) electrosynthesis with high productivity and high selectivity in oxygen reduction reaction (ORR) cannot be achieved simultaneously. In this work, the dual-metal-organic frameworks (NiFe-MOFs) is designed and synthesized, in which the eg orbital occupancy of Ni nodes is regulated by the super-exchange effect of Ni(2+σ)+-O-Fe(3-σ)+ bond. As a result, the binding strength between the cathode and the oxo-intermediates (*O2, *OOH) is optimized, which efficiently promotes oxygen reduction kinetics and inhibits O-O bond breakage. The H2O2 yield of NiFe-MOFs cathode reaches 1.83 mol·g−1·h−1 with a Faraday efficiency of 96.3 % at 0.5 V vs. RHE, which is far superior to Ni-MOFs (0.21 mol·g−1·h−1, 65.4 %), Fe-MOFs (0.65 mol·g−1·h−1, 57.5 %). This work offers a new strategy to design and develop cathodic catalysts for H2O2 electrosynthesis with high productivity and high selectivity.

Design a novel mixed-ligand Ni-MOF/MWCNT nanocomposite to enhance the electrochemical performance of supercapacitors

Metal-organic frameworks (MOFs) have garnered considerable interest for supercapacitors as electrode materials. Although MOFs possess large pore sizes and high specific surface areas, most MOFs face major challenges due to their inferior stability and low electronic conductivity. In this study, we synthesized Ni-MOF/MWCNT nanocomposite using a mixed-ligand approach through hydrothermal method to provide more redox reaction sites, facilitate ion diffusion, increase the stability, and electronic conductivity of the electrode. Benzoic acid (BA) has partially replaced Benzene-1,3,5-tricarboxylic acid (BTC). BTC has been used to shape Ni-MOF nanosheets into flower-like microspheres, which can reduce the electron/ion diffusion path. The introduction of BA and combination of MWCNT and Ni-MOF result in high electric conductivity. Furthermore, the combination of two organic ligands, and the synergistic effect of MWCNTs and Ni-based MOFs lead to excellent electrochemical performance. The prepared Ni-MOF/MWCNT nanocomposite shows an outstanding capacitance of 900 F g−1 at 0.5 A g−1 and excellent cycling stability with 82 % capacity etention over 1000 cycles. This study presents an innovative strategy for enhancing energy storage performance.

Open Active Sites in Ni-Based MOF with High Oxidation States for Electrooxidation of Benzyl Alcohol.

The kinetics of electrocatalytic reactions are closely related to the number and intrinsic activity of the active sites. Open active sites offer easy access to the substrate and allow for efficient desorption and diffusion of reaction products without significant hindrance. Metal-organic frameworks (MOFs) with open active sites show great potential in this context. To increase the density of active sites, trimesic acid was utilized as a ligand to anchor more Ni sites and in situ construct the nickel foam-loaded Ni-based trimesic MOF electrocatalyst (Ni-TMA-MOF/NF). When tested as an electrocatalyst for benzyl alcohol oxidation, Ni-TMA-MOF/NF exhibited lower overpotential and superior durability compared to Ni foam-loaded Ni-based terephthalic MOF electrocatalyst (Ni-PTA-MOF/NF) and Ni(OH)2 nanosheet array (Ni(OH)2/NF). Ni-TMA-MOF/NF required only a low potential of 1.65 V to achieve a high current density of 400 mA cm-2. Even after 40000 s of electrocatalytic oxidation at 1.5 V, Ni-TMA-MOF/NF maintained a current density of 175 mA cm-2 with ∼68% retention, showing its potential for benzyl alcohol oxidation. Through a combination of experimental and theoretical investigations, it was found that Ni-TMA-MOF/NF displayed superior electrocatalytic activity due to an optimized electron structure with high-valence Ni species and a high density of active sites, enabling long-term stable operation at high current densities. This study provides a new perspective on the design of electrocatalysts for benzyl alcohol oxidation.

Real direct urea fuel Fell operation using standalone Ni-based metal-organic framework prepared by ball mill at room temperature

Climate change and health issues are exacerbated by fossil fuel use. Efficient environmental energy conversion devices can reduce these effects. For the first time, we used a simple ball milling approach to manufacture a Nickel-based metal-organic framework (Ni-MOF) at ambient temperature directly onto a carbon cloth surface (Ni-MOF/CC) for a direct urea fuel cell (DUFC) anode. The prepared materials' crystaline structure, surface topography, and elemental content were studied using X-Ray diffraction and a scanning electron microscope with an EDS analyzer. Cyclic voltammetry, impedance electrochemical spectroscopy, and chronoamperometry were used in a three-electrode cell configuration to evaluate the material's electrochemical oxidation efficiency, particularly toward urea. In-Situ, under real fuel cell operation circumstances, we tested the electrodes in a two-electrode cell configuration. The Ni-MOF/CC exhibited a 0.35 V onset potential owed to Ni(OH)2 (Ni+2)/Ni+3 NiOOH active site. The electrode was stable for urea oxidation and operated well under real fuel cell conditions, producing 5 mW/cm2 using 1 M urea. The Ni-based MOF's fast charge and mass transfer capabilities, which was directly synthesized onto the carbon cloth surface, make the produced electrode operate well compared with bare carbon cloth. The results of the current work allow for more efficient environmental energy conversion devices that will reduce global warming.

Interpretable Data-Driven Descriptors for Establishing the Structure-Activity Relationship of Metal-Organic Frameworks Toward Oxygen Evolution Reaction.

The development of readily accessible and interpretable descriptors is pivotal yet challenging in the rational design of metal-organic framework (MOF) catalysts. This study presents a straightforward and physically interpretable activity descriptor for the oxygen evolution reaction (OER), derived from a dataset of bimetallic Ni-based MOFs. Through an artificial-intelligence (AI) data-mining subgroup discovery (SGD) approach, a combination of the d-band center and number of missing electrons in eg states of Ni, as well as the first ionization energy and number of electrons in eg states of the substituents, is revealed as a gene of a superior OER catalyst. The found descriptor, obtained from the AI analysis of a dataset of MOFs containing 3-5d transition metals and 13 organic linkers, has been demonstrated to facilitate in-depth understanding of structure-activity relationship at the molecular orbital level. The descriptor is validated experimentally for 11 Ni-based MOFs. Combining SGD with physical insights and experimental verification, our work offers a highly efficient approach for screening MOF-based OER catalysts, simultaneously providing comprehensive understanding of the catalytic mechanism.