Nitrogen-Doped Mixed-Phase Cobalt Nanocatalyst Derived from a Trinuclear Mixed-Valence Cobalt(III)/Cobalt(II) Complex for High-Performance Oxygen Evolution Reaction

Abstract

Because of a continuous increase in energy demands and environmental concerns, a focus has been on the design and construction of a highly efficient, low-cost, environmentally friendly, and noble-metal free electrocatalyst for energy technology. Herein we report facile synthesis of the mixed-valence trinuclear cobalt complex 1 by the reaction of 2-amino-1-phenylethanol and CoCl2·6H2O in methanol as the solvent at room temperature. Further, 1 was reduced by using aqueous N2H4 as a simple reducing agent, followed by calcination at 300 °C for 3 h, yielding a nitrogen-doped mixed phase cobalt [β-Co­(OH)2 and CoO] nanocatalyst (N@MPCoNC). Both 1 and N@MPCoNC were characterized by various physicochemical techniques. Moreover, 1 was authenticated by single-crystal X-ray diffraction studies. The hybrid N@MPCoNC reveals a unique electronic and morphological structure, offering a low overpotential of 390 mV for a stable current density of 10 mA cm–2 with high durability. This N@MPCoNC showed excellent electrocatalytic as well as photocatalytic activity for oxygen evolution reaction compared to 1.

A Highly Active Nitrogen‐Doped Mixed‐Phase Mixed‐Valence Cobalt Nanocatalyst for Olefins and Nitroarenes Hydrogenation

“…For Co2P XPS spectra showed the presence of both oxidation state of cobalt such as Co +2 and Co +3 in N@MPCoNC . The characteristic peaks of XPS spectrum for O1s and N1s confirms the presence of OH or surface absorbed oxygen and pyridinic nitrogen [59–61] …”

“…In PXRD analyses of N@MPCoNC contains β‐Co(OH) 2 and CoO whereas most of the peaks correspond to β‐Co(OH) 2 rather than CoO. The high intensity diffraction peaks represents the prepared material is crystalline in nature [59] . HRTEM analysis were carried out to observe the morphological features and size of the prepared nanomaterials.…”

“…We have synthesized and characterized a trinuclear mixed valence cobalt complex 1 and nitrogen doped mixed phase cobalt (β-Co(OH) 2 and CoO) nanocatalyst (N@MPCoNC) as reported earlier. [59] N@MPCoNC was synthesized via single source molecular precursor by reducing 1 by aq. N 2 H 4 followed by calcinations (Scheme 1).…”

“…[59] Nitrogen doped mixed phase cobalt nanocatalyst N@MPCoNC was thoroughly characterized by powder XRD, FTIR, BET, FESEM, HRTEM, TGA, UV, and XPS analyses and all these characterizations were fully explained in our previous work. [59] In PXRD analyses of N@MPCoNC contains β-Co(OH) 2 and CoO whereas most of the peaks correspond to β-Co(OH) 2 rather than CoO. The high intensity diffraction peaks represents the prepared material is crystalline in nature.…”

Rational Design of a Confacial Pentaoctahedron: Anisotropic Exchange in a Linear ZnIIFeIIIFeIIIFeIIIZnII Complex

“…[1,2] Confacial trioctahedra -homonuclear and heteronuclearhave been realized using different ligands and synthetic strategies. [9][10][11][12][13][14][15][16][17][18][19] E. g., the ligand L 3À (Scheme 1b) [14][15][16][17][18] was first reacted to form mononuclear complexes [LM t ] 0,nÀ as metalloligands that can coordinate a third central metal ion M c by their terminal S 3 facial coordination sites resulting in the confacial trioctahedra. A different synthetic strategy does not require the isolation of the metallo-ligand but generates and reacts it with the central metal ion M c in situ.…”