Modulating the Hydrothermal Synthesis of Co₃O₄ and CoOOH Nanoparticles by H₂O₂ Concentration

Abstract

The formation process and product control are very important in material synthesis. In this study, a facile one-pot hydrothermal method was used to prepare Co3O4 and CoOOH. H2O2 was used to modulate the formation process and control the final product by changing its concentration. The crystalline structures and morphologies of the as-prepared products were characterized by X-ray diffraction (XRD), Raman spectra, and scanning electron microscopy (SEM) techniques. It was found that the concentration of H2O2 influenced not only the phase of the final products but also their morphologies. The influences of H2O2 concentration on the precursor formation and the reaction path have been revealed. At a low concentration of H2O2 (5 wt %), the formed precursor is Co­(CO3)0.5(OH)·0.11H2O, which can be directly transformed into Co3O4 upon increasing the hydrothermal time. At a medium concentration (15–20 wt %), the formed precursor and the final product are all CoOOH. At a high concentration (30 wt %), the formed precursor is CoOOH, and the final product is Co3O4. H2O2 plays the role of oxidant agent at the initial stage or reducing agent at the subsequent stage. This study offers a H2O2-concentration modulating method for the formation of Co3O4 and CoOOH.

Tuning Co2+ Coordination in Cobalt Layered Double Hydroxide Nanosheets via Fe3+ Doping for Efficient Oxygen Evolution

“…The change of the Raman peak at 400–600 cm –1 reflects the complex process from adsorption of water molecules to O 2 precipitation. The characteristic peaks at 452 and 522 cm –1 assigned to Co/Fe–O vibration in LDHs gradually disappear with the progress of the reaction, and a group of new peaks appear instead. ,, The bands at 469 and 576 cm –1 correspond to the formation of E g bending and A 1g stretching vibrational modes of Co–O in the CoO­(OH) or CoO x species, ,, and the characteristic peaks of CoO­(OH) at 510 and 680 cm –1 are weak to be observed in Co3/Fe1 and Co5/Fe1 . It is worth mentioning that the electrochemical response of Co5/Fe1 is most rapid during the OER process, owing to the highly efficient electrocatalytic activity of Co5/Fe1.…”

“…52,64,65 The bands at 469 and 576 cm −1 correspond to the formation of E g bending and A 1g stretching vibrational modes of Co−O in the CoO(OH) or CoO x species, 52,66,67 and the characteristic peaks of CoO(OH) at 510 and 680 cm −1 are weak to be observed in Co3/Fe1 and Co5/Fe1. 68 It is worth mentioning that the electrochemical response of Co5/Fe1 is most rapid during the OER process, owing to the highly efficient electrocatalytic activity of Co5/Fe1. According to the above result and further analyzing the structure of Fe-doped Co-LDH, we infer that the reason for electronic changes is mainly because Fe is doped into the CoO 6 octahedron layer and replaces some of the CoO 4 tetrahedrons.…”

Non‐enzymatic glucose sensor based on three‐dimensional hierarchical Co 3 O 4 nanobooks

“…The diversity of the polar sites is beneficial for detecting charges produced in the electrocatalytic reaction [19]. It is found that the performance of non‐enzymatic glucose sensors can be tuned and enhanced efficiently by tailoring the nanostructures of Co 3 O 4 materials, including nanoparticles [20, 21], twin‐spheres [22], microspheres [23, 24], nanofibres [25, 26], nanowires [27, 28], nanorods [29, 30], nanosheets [1], nanoflowers [31], and so on. Among them, three‐dimensional (3D) hierarchical Co 3 O 4 nanoarchitectures are particularly interesting due to their excellent electrochemical performances, which result from their favourable specific surface area and stable 3D network.…”

Porous N-doped carbon with confined Fe-doped CoP grown on CNTs for superefficient oxygen evolution electrocatalysis

“…4b). 25,26 These results revealed the transformation from Fe-CoP to Fe-CoOOH during the OER process.…”