Cobalt Phosphonate Research Articles

Hybrid bimetallic phosphonates as cathode materials for miniaturized in-plane asymmetric supercapacitor device

The utilization of wearable electronic devices facilitates the development of smart and flexible technology as a superior energy storage device that minimizes the dimension of wearable devices. The simple vacuum filtration method was employed to fabricate the micro-supercapacitor device (MSC) using the as-synthesized bimetallic nickel cobalt phosphonate (NiCoNPO) on the PVDF membrane as substrate. Novel microporous bimetallic metal phosphonates (NiCoNPO, Ni2CoNPO, NiCo2NPO) have been synthesized in a hydrothermal reaction condition by varying the molar ratio (Ni1:Co1; Ni2:Co1; Ni1:Co2) of metal sources without any employment of templating agent. Among these, NiCoNPO exhibits the remarkable specific capacitance of 2308 F g−1 at 1 mV s−1 and long-term cyclic stability up to the 5000th cycle with 99.6 % capacity retention in the three-electrode system. In addition, the electrode material demonstrates an exceptional capacitance of 574 F g−1 with stability (87.6 % retention) in a two-electrode system. Also, it displays excellent performance as a flexible MSC device with an areal capacitance of 123.5 mF cm−2. Notably, the MSC demonstrates long-term stability up to the 5000th cycle with a capacity retention of 85.6 %, suggesting the electrode material has excellent mechanical flexibility and superior electrochemical performance.

Greener production of styrene via low-temperature dehydration of phenethyl alcohol over Co-supported P/ZrO2

Despite the rising need for styrene, the alternative method of synthesis from bio-based alcohols is little explored and poorly understood. We have investigated the option for the alternate produce styrene via vapour-phase dehydration of phenethyl alcohol using a cobalt phosphonate zirconia oxide. The Study demonstrates that a metallic element (cobalt) is essential for dehydrating phenethyl alcohol, restricting the decomposition of styrene to polystyrene acid. This Co phosphonate-zirconium-based catalyst exhibits selective styrene from phenylethanol, showing a much greener route to producing styrene and lower activation energy (Ea = 54.36 KJ/mol) than other solid acid catalysts used so far. An 88.6 % conversion of phenethyl alcohol was achieved with a selectivity of 75.1 % over 4.5CoP/ZrO2 catalyst.

Robust water splitting based on new microporous hybrid iron cobalt phosphonate as efficient bifunctional electrocatalyst

The facile synthesis of microporous hybrid bimetallic iron-cobalt phosphonate (FeCoNAPH) has been reported under easy hydrothermal condition without using any kind of template. With the lower overpotential values of 154 and 132 mV at 10 mA cm−2 and having lower Tafel slopes, the electrocatalyst displays outstanding catalytic activities for OER and HER, repetitively in basic medium. The as-synthesized FeCoNAPH is a cost-effective material employed in practical applications, and it is analogous to the standard catalysts such as IrO2 and Pt/C (10 wt%). Having a high specific surface area with regular microporosity, the FeCoNAPH displays exceptional electrocatalytic activity, which could be utilized for commercialization purposes in the future to substitute the high-cost effectiveness and scarcity of noble metals. Additionally, the as-synthesized electrocatalyst exhibits long-term durability with the required cell potential of 1.43 V to attain 10 mA cm−2 for a two-electrode overall water splitting (OWS) system. Notably, the spherical structure helps in the production of a greater number of electroactive sites, which leads to a faster rate of kinetics of the development of electroactive intermediate species.

Iron Cobalt Phosphonate Derived Heteroatom Doped Metal Oxides as Superior Electrocatalysts for Water Oxidation Reaction

AbstractThe development of low cost‐effective and highly efficient heterogeneous electrocatalysts is most appreciable in the research community. A newly designed microporous organic‐inorganic hybrid iron cobalt phosphonate (FeCoDPAM) is synthesized using diphenylphosphinamide as an organophosphorus ligand through a hydrothermal pathway without any template. To synthesize N, P‐codoped bimetallic oxides (NP/FeCoO350, NP/FeCoO550, and NP/FeCoO750), the as‐synthesized material FeCoDPAM has undergone pyrolysis at three different temperatures, i. e., 350, 550, 750 °C, respectively. The high specific surface area and a regular microporous array of N, P‐codoped iron cobalt oxide (NP/FeCoO350) material provide excellent oxygen evolution reaction (OER) activity. The NP/FeCoO350 material catalyzes OER with the overpotential of 331 mV at a current density of 10 mAcm−2 and Tafel slope of 56.7 mV dec−1 in 1.0 M KOH solution. The inclusion of iron in the cobalt phosphonate framework can change the electronic structure, and electron transfer can be feasible to the d‐orbital of cobalt. Due to the doping of heteroatoms such as N and P into the bimetallic oxide matrix, a synergistic effect can occur, which is the driving force for the efficient electrocatalytic OER activity. Also, the FeCoO350 displays stability with outstanding oxidative current up to 50 h time in chronoamperometry measurement.

Newly designed microporous organic-inorganic hybrid cobalt phosphonate for hydrogen evolution reaction

The electrochemical water splitting through hydrogen evolution reaction (HER) is a promising technique for generating clean hydrogen as alternative energy to fossil fuel. In recent times, various kinds of cobalt-based materials have been synthesized for hydrogen evolution reactions due to their good catalytic activity, robust structure and stability. New microporous organic-inorganic hybrid cobalt phosphonate material (CoGLy) was developed by a hydrothermal reaction pathway without any structure-directing agent. The material has been characterized through important tools such as powder X-ray diffraction, Nitrogen sorption, Fourier-transform infrared spectroscopy, High-resolution transmission electron microscopy, Field emission scanning electron microscope, and X-ray photoelectron spectroscopy technique. Notably, the material possesses a high specific surface area with a proper microporous channel, which are the key parameters for achieving excellent electrocatalytic activity towards HER. The as-synthesized CoGLy catalyst displays the high catalytic efficiency with the overpotential of 125 mV to acquire the current density of 10 mA cm−2 and low Tafel slope of 72 mV dec−1. Also, the CoGLy catalyst shows outstanding stability in chronoamperometry measurement up to 25 h time without significant change in current density.

Precisely modifying Co2P/black TiO2 S-scheme heterojunction by in situ formed P and C dopants for enhanced photocatalytic H2 production

The construction of S-scheme heterojunction catalysts is promising for efficient photocatalytic hydrogen production, but the conscious modulation of S-scheme charge transfer has remained largely underdeveloped. Herein, P and C modified Co2P/black TiO2 S-scheme heterojunction photocatalyst (Co2P/PC-b-TiO2) is prepared by pyrolyzing a mixture of cobalt phosphonate and TiO2 under H2 atmosphere. The in situ formed P and C dopants can not only enhance the ratio of surface active O species to bulk O defects but also inhibit anatase-to-rutile phase transformation, thereby ensuring the high intrinsic activity. More importantly, the S-scheme heterojunction between PC-b-TiO2 and Co2P is modified by the incorporation of P and C, wherein the intimately coupled heterointerface and strong internal electric field can accelerate charge separation and migration and optimize the available redox potential. Accordingly, Co2P/PC-b-TiO2 displays dramatically ascendant photocatalytic hydrogen evolution performance and outstanding stability. This study provides guidance for elaborately modifying S-scheme heterojunctions through heteroatom doping and heralds a new paradigm for engineering advanced heterojunction catalysts.

Novel microporous organic-inorganic hybrid metal phosphonates as electrocatalysts towards water oxidation reaction

In recent years, the development of electrochemical water oxidation requires an efficacious heterogeneous electrocatalyst to improve the high catalytic activity. Herein, newly designed three transition metal-based phosphonate materials i.e., cobalt phosphonate (CoEDA), nickel phosphonate (NiEDA), and nickel-cobalt phosphonate (NiCoEDA), were synthesized using etidronic acid (1-Hydroxyethane 1,1-diphosphonic acid) as the organophosphorus source under hydrothermal reaction condition at pH 6.5. Among these materials, CoEDA exhibits a high surface area with a proper microporous channel, one of the key parameters for showing excellent electrocatalytic activity towards oxygen evolution reaction (OER) with a lower overpotential (318 mV) and Tafel slope (70.1 mV dec−1). The superior catalytic activity towards OER can be correlated with the presence of the organic-inorganic hybrid material containing Co-O-P bond and the formation of highly electroactive cobalt oxyhydroxide (CoOOH) species onto the pore wall of the microporous channel. Besides, as-synthesized CoEDA catalyst displays outstanding catalytic stability for 25 h with a change in current density of only 6%.

Charge Separated One-Dimensional Hybrid Cobalt/Nickel Phosphonate Frameworks: A Facile Approach to Design Bifunctional Electrocatalyst for Oxygen Evolution and Hydrogen Evolution Reactions.

Two new organoamine templated one-dimensional transition metal phosphonate compounds are synthesized, and their bifunctional electrocatalytic activities are examined in highly alkaline and acidic media. Compared with state-of-the-art materials, the cobalt phosphonate system is a new fabrication of sustainable and highly efficient catalysts toward electrochemical water splitting systems.

Two three-dimensional mixed-ligated cobalt phosphonate coordination polymers: Syntheses, crystal structures and magnetic properties

Two new mixed-ligated cobalt phosphonates, Co5(pbtc)2(4,4′-bpy)2(H2O)4·2H2O (1) and Co4.5(pbtcH0.5)2(bpm)(H2O)6·4H2O (2) (pbtcH5 = 5-phosphonatophenyl-1,2,4-tricarboxylic acid, 4,4′-bpy = 4,4′-bipyridine and bpm = 2,2′-bipyrimidine), are obtained by incorporating 4,4′-bipyridine and 2,2′-bipyrimidine co-ligands, respectively. Compound 1 has infinite chains constructed by the alternative arrangement of Co3 trimers and Co2 dimers, which are connected by pbtc5− and 4,4′-bpy to form a three-dimensional framework structure. For compound 2, zigzag-like pentamers of Co are connected by pbtc5− and bpm ligands achieving a different type of three-dimensional framework structure. The lattice water molecules fill in the void space in the framework structures of both compounds. Magnetic measurements show that the antiferromagnetic interactions are dominated in compound 1, while the weak ferromagnetic exchange couplings are observed in compound 2.

Iron anchored microporous cobalt phosphonate novel nanostructure for efficient oxygen evolution reaction

Very recently, microporous transition metal-based organic-inorganic hybrid phosphonate nanostructured materials have attracted attention for their good potential in electrocatalytic application involving oxygen evolution reaction (OER). Newly designed Iron anchored microporous cobalt-based phosphonate materials i.e. FeCoNTMP has been synthesized utilizing nitrilotri(methylphosphonic acid) under the hydrothermal reaction condition in absence of any structure directing agent (SDA). Moreover, FeCoNTMP material exhibits excellent catalytic performance towards electrochemical oxygen evolution reaction with the low overpotential value of 289 mV at the current density of 10 mA cm−2 in 1.0 M basic solution whereas Tafel slope was 59.3 mV dec-1. In addition, FeCoNTMP catalyst displays the outstanding durability up to 25 h, suggesting the potential heterogeneous electrocatalyst.

Insight into the Active Contribution of N-Coordinated Cobalt Phosphate Nanocrystals Coupled with Carbon Nanotubes for Oxygen Electrochemistry

The exploration of efficient nonprecious bifunctional electrocatalysts toward both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is highly desirable for the development of the rechargeable metal–air battery. Herein, “diamond necklace”-like N-coordinated cobalt phosphate nanocrystals coupled with carbon nanotubes (CoPiC-DP/CNTs) are synthesized through the facile hydrothermal-carbonization approach and employed as the bifunctional electrocatalyst for ORR and OER. The CNTs act like the “chain” as support, the “diamond”-like N-coordinated cobalt phosphate nanocrystals serve as catalytic active sites, and the N-doped carbon derived from the phosphonate ligand-like “linker” can not only protect the “diamond” from leaching but also promote the mass transfer. Such advanced structure and composition features endow CoPiC-DP/CNTs with impressive ORR and OER electrochemical activities. To probe the active contribution of CoPiC-DP/CNTs toward ORR, a series of cobalt phosphate–carbon hybrids are prepared by adjusting the types of phosphonate ligands of the cobalt phosphonate precursor to rationally control their active components. The comprehensive investigation from structural characterizations and electrochemical measurements of these cobalt phosphate–carbon hybrids verifies that both N-coordinated cobalt sites and the suitable carbon substrate are essential for the enhanced electrocatalytic performance. Furthermore, the liquid- and solid-state zinc–air batteries with these fabricated CoPiC-DP/CNTs employed as the air cathode exhibit decreased charge–discharge potential gaps, high power density, and considerable cycling durability, which are beneficial for the potential development of flexible/portable electronic devices.

Fabrication of new structures from a 3D cobalt phosphonate network: structural transformation and proton conductivity investigation

Three new compounds with novel structures were prepared from cobalt 318, among which, 0-dimensional structural compound 1 shows a higher proton conductivity.

Microporous metal phosphonate-based N-doped graphene oxide for efficient electrocatalyst for water oxidation

Nowadays, microporous hybrid metal phosphonates have displayed very good electrocatalytic activity towards oxygen evolution reaction (OER). Herein, microporous cobalt phosphonate (CoImP) has been synthesized using Iminodi(methylphosphonic acid) as an organophosphorous source without utilizing any structure directing agent. Also, the cobalt phosphonate-based N-doped graphene oxide (CoImP/N-GO) has shown the excellent OER activity due to the good conductive property, high surface area with proper microporous channel and the formation of electroactive CoOOH species on the surface of pore wall. In addition, CoImP/N-GO material displays the outstanding static current density up to 25 h time, suggesting the good stability of the material.

Novel microporous cobalt phosphonate: Efficient heterogeneous catalyst towards oxygen evolution reaction

In recent years, organic-inorganic hybrid transition metal-based phosphonate nanomaterials have gained immense attention due to their high electrocatalytic efficiency in oxygen evolution reaction (OER). Newly synthesized porous cobalt-based phosphonate materials i.e. CoNTO-1-3 and CoNTO-1-4 have been synthesized using nitrilotri(methylphosphonic acid) under the hydrothermal reaction condition without utilization of any structure directing agent. Among them, CoNTO-1-3 material displays high catalytic activity towards electrochemical OER having low overpotential value of 312 mV at 10 mA cm−2 current density in 1.0 M basic (KOH) solution where Tafel slope was 61.1 mV dec−1. Also, CoNTO-1-3 catalyst exhibits the good stability up to 25 h.

Halogen bonding interactions assisted network expansion of a tetrahedral cobalt phosphonate coordination polymer bearing 4,4′-bipyridine ligand

A new cobalt phosphonate coordination polymer {[Co2(BrBzPO3)2(bpy)]∙2H2O}n (1) has been synthesized from the reactions of Co(NO3)2, 2-bromobenzyl phosphonic acid (BrBzP(O)(OH)2), and 4,4′-bipyridine (bpy) via reactants slow diffusion in H2O/ethanol solvent media at 60°C. Single-crystal X-ray diffraction analysis reveals that the Co(II) center has a {CoO3N} tetrahedral geometry. The coordinative network of 1 shows a layer structure constructed from Co–BrBzPO3 chains, which contain four-membered rings assembled from vertex-sharing {CoO3N} and {CPO3} tetrahedral units, connected by bpy linkers. It is worthy to note that net-to-net Br–Br halogen bonding interactions play the key supramolecular interactions to significantly dominate network expansion from a two-dimensional (3,4)-connected coordinative layer with a point symbol of (426)(42638) to a three-dimensional (4,4)-connected supramolecular network having a point symbol of (42638)(42638). Further, there are multiple noncovalent supramolecular interactions involving strong O–H∙∙∙O and weak C–H∙∙∙Br and C–H∙∙∙π interactions that provide powerful supports for stabilizing the whole crystal structure. Thermogravimetric (TG) analysis indicates that the coordinative network of 1 is high thermally stable upon heating to 340°C.

Novel porous metal phosphonates as efficient electrocatalysts for the oxygen evolution reaction

Recently, metal-doped organic-inorganic hybrid nanomaterials have attracted substantial attention for their high catalytic activity in the electrochemical oxygen evolution reaction (OER). Here, we report three novel porous metal phosphonates, cobalt phosphonate (CoPIm), nickel phosphonate (NiPIm), and nickel-cobalt phosphonate (NiCoPIm), using iminodi(methylphosphonic acid) as an organophosphorous precursor via a hydrothermal nontemplated synthetic route. All three materials have been explored as electrocatalysts for the OER. Notably, the CoPIm material exhibits excellent electrocatalytic behavior among all of the as-prepared catalysts. The high surface area and the formation of active CoOOH species on the catalyst surface during the OER process are the main driving force for a superior electrochemical OER. The CoPIm catalyst requires a very small overpotential (334 mV) to reach the current density of 10 mA cm−2 in 1.0 M KOH solution with a Tafel slope of 58.6 mV dec−1 as compared to NiPIm, NiCoPIm, and commercial IrO2. Additionally, the prepared CoPIm catalyst shows excellent stability up to 25 h, suggesting its potential in electrochemical water splitting.

Boosting water oxidation activity by tuning the proton transfer process of cobalt phosphonates in neutral solution.

Water oxidation is a vital step in both natural and artificial photosynthetic processes. However, the effect of second coordination sphere for efficient oxygen evolution electrocatalysts has rarely been studied, becoming a bottleneck in many energy-related issues. In this article, the cobalt phosphonate (NH3C6H4NH3)Co2(hedpH)2·H2O (Co-PDA) displayed decent electrocatalytic water oxidation activity in 50 mM PBS solution (pH 7.0), comparable to the activity of state-of-the-art IrO2. Moreover, it exhibited a 160 mV lower onset potential and 6 times higher TOF than those of the counterpart, (NH4)2Co2(hedpH)2 (Co-NH4+), which existed with the same Co active center, while surrounded by different ligands. The related mechanistic studydemonstrates that the ligand in Co-PDA would benefit the proton-coupled electron transfer (PCET) processes and the formation of high valence state Co(iv).

Detecting structural transformation of cobalt phosphonate to active bifunctional catalysts for electrochemical water-splitting

An in situ transformation of cobalt phosphonate precursor to two distinct active catalyst structures at the anode and cathode during electrochemical water splitting has been uncovered by spectroscopic and microscopic techniques.

Phosphonate-derived nitrogen-doped cobalt phosphate/carbon nanotube hybrids as highly active oxygen reduction reaction electrocatalysts

The exploration of cost-effective non-noble-metal electrocatalysts is highly imperative to replace the state-of-the-art platinum-based catalysts for oxygen reduction reaction (ORR). Here, we prepared cobalt phosphonate-derived N-doped cobalt phosphate/carbon nanotube hybrids (CoPiC-N/CNTs) by hydrothermal treatment of N-containing cobalt phosphonate and oxidized carbon nanotubes (o-CNT) followed by high-temperature calcination under nitrogen atmosphere. The resultant CoPiC-N/CNT exhibits a superior electrocatalytic performance for the ORR in alkaline media, which is equal to the commercial Pt/C catalyst in the aspect of half-wave potential, onset potential and diffuse limiting current density. Furthermore, the excellent tolerance to methanol and strong durability outperform those of commercial Pt/C. It is found that cobalt phosphonate-derived N-doped cobalt phosphate and the in-situ formed graphitic carbons play key roles on the activity enhancement. Besides, introducing a suitable amount of CNTs enhances the electronic conductivity and further contributes to the improved ORR performance.

Amorphous cobalt phosphate porous nanosheets derived from two-dimensional cobalt phosphonate organic frameworks for high performance of oxygen evolution reaction

Two-dimensional cobalt phosphonate organic frameworks nanosheets were synthesized by a bottom-up chemical precipitation method. Different products were obtained by controlled calcination of the cobalt phosphonate organic frameworks. Results of products obtained at different temperatures were analyzed. The product obtained after calcination at 600 °C was amorphous, porous, and retains the original sheet-like structure of the two-dimensional cobalt phosphonate organic frameworks. The amorphous cobalt phosphate exhibited excellent reactivity in the oxygen evolution reaction. At 10 mA cm−2, the overpotential was only 278 mV, and the Tafel slope was 80 mV dec-1. The porous structure makes the amorphous cobalt phosphate have a large free space, increases the distribution of the active center, and facilitates the diffusion of hydroxide. The two-dimensional nanosheet structure has a high proportion of exposed metal atoms on the surface, and these coordinated unsaturated metal centers are important for electrocatalysis.