In Situ Transformed Cobalt Metal–Organic Framework Electrocatalysts for the Electrochemical Oxygen Evolution Reaction

Abstract

The development of an active and efficient electrocatalyst for the oxygen evolution reaction remains indispensable for the smooth running of an electrolyzer. Herein, we have synthesized two cobalt metal–organic frameworks (Co-MOFs) with the formulas [C6H6CoN2O4] (compound 1) and [C12H10CoN2O4] (compound 2) using pyrazine and 4,4′-bipyridine as linkers in dimethylformamide medium by a solvothermal method. Both Co-MOFs shows strong antiferromagnetic interactions with Θp = −70 and −61 K for compounds 1 and 2, respectively. The in situ transformation of both compounds catalyzes the OER efficiently in alkaline medium, affording a current density of 10 mA/cm2 at overpotentials of 276 ± 3 and 302 ± 3 mV by compounds 1 and 2, respectively. Moreover, compound 1 shows a very high turnover frequency (15.087 s–1), lower Tafel slope (56 mV/dec), and greater Faradaic efficiency of 95.42% in comparison to compound 2. The transformations of the Co-MOFs have been accessed by employing powder X-ray diffraction (PXRD), high-resolution transmission electron microscopic (HRTEM) analysis, and X-ray photoelectron spectroscopy, which reveal the formation of uniform hexagonal Co­(OH)2 plates. Therefore, the as-developed Co-MOF is found to be an efficient pre-electrocatalyst for the OER in alkaline medium. These results not only reveal the preparation of OER electrocatalysts from a Co-MOF but also establish a method to derive a potentially active electrocatalyst to substitute for the traditional noble-metal-based materials.

Cobalt metal organic framework (Co-MOF) derived CoSe2/C hybrid nanostructures for the electrochemical hydrogen evolution reaction supported by DFT studies

“…Therefore, current research focuses on the designing of methodologies to derive metal nanostructures from these MOFs and make composites with carbon to achieve better electrocatalytic behavior. 17–20 In this report, we designed a novel approach for the synthesis of CoSe 2 encapsulated in a graphitic carbon network from cobalt metal organic framework [Co 4 (BTC) 3 (BIm) 6 ] by selenization through a solvothermal method. Here, the single reaction step simultaneously makes the possible selenization of the metal centers as well as graphitization of the carbon framework present in the MOF, forming the hybrid structure (CoSe 2 /C).…”

Co‐MOF Nanosheet Arrays for Efficient Alkaline Oxygen Evolution Electrocatalysis

“…In Figure 3a, the oxidation peak of Co‐MOF/NF at 1.25 V is attributed to the change of Co 2+ into Co 3+[35] and the peak of bare NF at 1.48 V is ascribed to the change of Ni 2+ into Ni 3+ [36] . It is worthwhile mentioning that Co‐MOF/NF is superior to most reported Co‐based MOF catalysts in alkaline condition (Table S1), such as Co‐MOF [37] (η10 mA cm −2 =302 mV), Co‐BTC‐5 wt % rGO [38] (η10 mA cm −2 =290 mV), UTSA‐16 [39] (η10 mA cm −2 =408 mV), Co‐MONs [40] (η10 mA cm −2 =309 mV), etc. Figure 3b displays the Tafel slopes for Co‐MOF/ NF, RuO 2 /NF, Co‐MOF powder/NF and bare NF, where it can be seen that the Co‐MOF/NF has a smaller Tafel slope of 74 mV dec −1 than that of Co‐MOF powder/NF (109 mV dec −1 ) and even the commercial RuO 2 grown on NF (75 mV dec −1 ), suggesting Co‐MOF/NF owns more favorable catalytic kinetics.…”

Interfacial interaction induced OER activity of MOF derived superhydrophilic Co3O4–NiO hybrid nanostructures

“…MOF derived materials contain controllable surface functionalities and a very high surface area and hence can be used as promising materials for several electrocatalytic applications. [19][20][21][22][23][24][25][26] Herein, we have synthesized the two-dimensional Co 2 -BDC(OH) 2 MOF over NF hydrothermally followed by controlled calcination leading to the generation of a uniform heterostructure of spinel cobalt oxides/nickel oxides over NF. The interface formation between Co 3 O 4 and NiO nanoparticles induces a synergistic effect, leading to an excellent OER performance with the overpotential value of 311 mV at 10 mA cm −2 current density in 1 M KOH.…”