Synthesis and Characterization of Nickel Cobalt Glycerate Derived Nickel Cobalt Based Metal-Organic Framework

This study produced Ni/CO-MOF material from Ni/Co-Glycerate with Ni:Co composition ratios of 1:2, 1:5, and 1:10. The Ni/Co-Glycerate template was synthesized using the solvothermal method at 180°C for 16 hours and dried at 60°C for 6 hours. MOFs were synthesized by dissolving Ni/Co-Glycerate as the metal ion source and 2-mIM as the ligand in distilled water at room temperature. The precipitate was washed with ethanol and dried for 16 hours at 80°C. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier-Transform Infrared (FT-IR) were used to examine material properties. The XRD results show that increasing the concentration of nickel metal can increase crystallinity, according to increasing intensity peaks at 2θ of 7.19°, 10.30°, 12.39°, and 17.88°. The morphology of Cu/Ni-MOF is hybrid; the hydroxide phase has a flower-like morphology, and MOFs have a circular shape. FT-IR spectra show the same spectrum absorption peaks band. The similarity of the peaks indicates that the functional groups in the Ni/Co-MOF material are the same at different metal concentrations.


Introduction
A Metal-Organic Framework (MOF) is a material composed of metal ions or clusters coordinated with organic ligands to form a porous, three-dimensional framework [1][2][3].MOFs are highly versatile and have received significant attention in various fields due to their unique properties, such as high surface area, tuneable porosity, and diverse functionality [4][5][6].MOFs have gained substantial attention in recent years owing to their diverse applications in catalysis, gas storage, separation, sensing, and drug delivery.Modifications can be applied to MOFs to improve physical, chemical, and functional properties.Several common methods for modifying MOFs include incorporating guest molecules, developing hybrid MOFs, and forming bimetallic or multimetallic MOFs [7][8][9].According to the many MOF materials, bimetallic nickel and cobalt-based metal-organic frameworks (Ni/Co-MOF) attract the interest of researchers due to their potential in distinct redox behaviors, catalytic activity, and electrochemical applications [10][11][12][13][14][15].
An especially intriguing approach to MOF synthesis involves using precursor materials derived from complexing agents such as glycerol [16][17][18][19][20]. Glycerol, a renewable and biodegradable compound, is an intriguing precursor for MOF synthesis due to its renewable nature and multifunctional hydroxyl groups that can act as coordinating sites during MOF formation [21,22].Its ability to coordinate with metal ions makes it an ideal candidate for preparing precursor materials for MOF synthesis.The formation of metal glycerates and their subsequent conversion into MOFs represents a promising route for the controlled fabrication of MOFs with tuneable composition, structure, and properties [23][24][25].
This paper focuses on synthesizing and characterizing nickel cobalt glycerate-derived MOF, particularly emphasizing the effect of metal composition ratio as transition metals with abundant coordination geometries on material properties.Nickel and cobalt provide a platform for designing MOFs with diverse morphologies and functionalities.The insights gained from the structural and property characterization pave the way for future studies to optimize MOF synthesis routes and tailor their functionalities for specific applications.

Chemicals
), 2-propanol, and Glycerol (C 3 H 8 O 3 ) were acquired from SIGMA-ALDRICH in Germany.These chemicals were commercially sourced and utilized directly without undergoing any additional purification steps.

Synthesis of Ni/Co -Glycerate as Template Material
The solvothermal method created a bimetal complex of Ni/Co-Glycerate.In 40 ml of 2-Propanol ( 3 ) 2 .6 2  and ( 3 ) 2 .3 2  were dissolved until a homogeneous solution with Ni and Co composition ratio of 1:2, 1:5, 1:10.After that,  3  8  3 (8 ml) added to the Ni/Co solution until completely dissolved.The solution was placed in a 100 ml sealed Teflon-lined stainless steel autoclave.After 16 h of reaction at 180℃, the precipitates were collected by centrifugal separation, then subjected to an ethanol wash, and finally dried at 60℃ for 6 hours.

Synthesis of Ni/Co -MOF
The preparation of Ni/Co-MOF involved dissolving Ni/Co-Glycerate (20 mg) in distilled water (20ml) for 6 h at room temperature.Subsequently, 2-mIM (0.5 gr) was gradually introduced into the solution and stirred for one hour.The precipitate was washed with ethanol until the pH was close to normal.Finally, the precipitate was dried for 16 h at 80℃.

Materials Characterization
XRD patterns were characterized by a Rigaku Minifex advanced instrument diffractometer.The morphologies and microstructures of the materials were examined with a Thermoscientifict: Quanta 650.FT-IR spectra were obtained using a Shimadzu-Japan Prestige 21.

Materials Characterization
Figure 1 shows the phase composition of the Cu/Ni MOF was evaluated by XRD (λ=0.15405nm) between 3-90°.Ni/Co-MOF with a Ni:Co concentration ratio of 1:2 (Fig. 1a) shows no peaks appearing, indicating the amorphous phase of the MOF.Increasing the concentration of Co 2+ ions can increase crystallinity, according to increasing intensity peaks at 7.19°, 10.30°, 12.39°, and 17.88°.The absence of a significant peak shift indicates that Co 2+ ions have replaced Ni 2+ ions.According to the theory of complex compound formation, the central metal ion can be replaced by another metal ion with the same coordination number and charge but a slightly different ionic radius [26].The microstructures and morphologies of Ni/Co MOF were examined using SEM.The effect of the increase in concentration of Co 2+ metal ions can be seen clearly in Figure 2. The effect of adding 2-mIM as a ligand at the nickel and cobalt metal nodes changes the morphology of the material from spherical [25] to hybrid phase.Hydroxides have a flower-like morphology, whereas MOFs have a disk-shape.The presence of an N-H (amine) group with an imidazole ring vibration is indicates by absorption between 900-650 cm -1 , at 991 cm -1 is a bend of the C-H group (alkene) [25].The C-O stretching vibrations (alcohols) are observed in the 1300-1000 cm -1 range, and aromatic C-C stretching shows at 1600-1400 cm -1 [28,29].The absorption band between 3500-3400 cm -1 assigned to the stretching vibration of the OH group from hydroxyl, indicating that water molecules are bound to the material [30].

Conclusion
In summarised, synthesizing and characterizing a novel MOF derived from nickel cobalt glycerate precursors.The study focuses on developing a nickel cobalt-based MOF through a controlled synthetic approach using glycerate ligands.The resulting MOF's structural properties, morphology, and composition are comprehensively characterized using various analytical techniques, including XRD, SEM, and FT-IR.The successful synthesis and characterization offer insights into the formation mechanism and properties of the nickel-cobalt glycerate-derived MOF.This research contributes to the growing field of MOF synthesis and provides a foundation for potential applications in catalysis, sensor, supercapacitor and other relevant areas due to the unique properties of Ni/Co MOFs.

Figure 3
Figure3shows that FT-IR has the same spectrum absorption peaks band.The similarity of the peaks indicates that the functional groups in the Ni/Co-MOF material with different concentrations of metals are the same.The wavenumber at ~700 cm -1 indicates the M-O bond in the Cu/Ni metal complex[27].The presence of an N-H (amine) group with an imidazole ring vibration is indicates by absorption between 900-650 cm -1 , at 991 cm -1 is a bend of the C-H group (alkene)[25].The C-O stretching vibrations (alcohols) are observed in the 1300-1000 cm -1 range, and aromatic C-C stretching shows at 1600-1400 cm -1[28,29].The absorption band between 3500-3400 cm -1 assigned to the stretching vibration of the OH group from hydroxyl, indicating that water molecules are bound to the material[30].