Mn-doped Ni(OH)₂ Nanostructures as an Efficient Electrocatalyst for Methanol Oxidation in Basic Solution

Abstract

The Mn-doped Ni(OH) 2 nanostructures were obtained by a simple ion-exchange hydrothermal method. The as-prepared materials were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) for their morphological, composition and structural properties. As a material for modified electrodes, electrochemical tests demonstrate that the methanol oxidation peak current density of Mn-doped Ni(OH) 2 nanostructures reached 14.18 mA cm −2 at 0.596 V (vs Ag/AgCl) in NaOH electrolyte. Similarly, the Mn-doped Ni(OH) 2 nanostructures also maintained good electrocatalytic stability during the term of 36,000 s. The improvement of electrochemical performance is related to the introduction of Mn element in Ni(OH) 2 . It may promote Ni in the Mn-doped Ni(OH) 2 nanostructures to carry the lower electron density and the higher oxidation state which may be responsible for the better performance toward methanol oxidation.

Alcohol oxidation with high efficiency and selectivity by nickel phosphide phases

“…[12][13][14][15][16] Among the proposed materials to replace noble metals as catalysts for alcohol oxidation, transition metals, especially Ni, are a cheap alternative and produce valuable products such as aliphatic acids with very high selectivity. 10,[16][17][18][19] So far, faceted Ni nanoparticles, 20 Ni 3 C branched nanoparticles, 18 NiO, 21,22 Ni(OH) 2 , 23,24 doped NiO 25 and Ni(OH) 2 , 26 and Ni nitrides and selenides have been synthesized and tested, mainly for methanol oxidation. The accumulated body of knowledge points to a thin layer of oxidized Ni as the active material, usually Ni(OH) 2 , which is electrochemically oxidized to NiOOH and reduced back to Ni(OH) 2 as the alcohol (or water) is oxidized.…”

Dual Matrix Influence on Ni(II) Rich Hybrid Catalyst for Electrochemical Methanol Oxidation Reaction

“…Similarly, in the case of Ni, the binding energy values for Ni 2p 3/2 and Ni 2p 1/2 were found in the range of 855.1–856 eV and 872.9–873.5 eV, respectively for Ni(OH) 2 . The satellite peaks observed in the range of 861.3–861.6 eV and 879.6–879.8 eV were also the characteristic peaks of the Ni 2+ state for Ni(OH) 2 species, Figure 2d–f [24,52] . The XPS of Al, Si, C, and O are provided in the supporting information, Figure S1–S3.…”

“…[50,51] Similarly, in the case of Ni, the binding energy values for Ni 2p 3/2 and Ni 2p 1/2 were found in the range of 855.1-856 eV and 872.9-873.5 eV, respectively for Ni(OH) 2 . The satellite peaks observed in the range of 861.3-861.6 eV and 879.6-879.8 eV were also the characteristic peaks of the Ni 2 + state for Ni(OH) 2 species, Figure 2d-f. [24,52] The XPS of Al, Si, C, and O are provided in the supporting information, Figure S1 S2a and S3a. [24,53] The O 1s bands for the material MnO 2 À Ni(OH) 2 -Y the band obtained at 532.9 eV, 531.1 eV and 529.8 eV for SiÀ O, Al 2 O 3 and MÀ O species respectively present in the material, Figure S1a.…”

Hybrid 2D‐1D nanostructure of NiO composited with PEDOT : PSS and rGO : Bifunctional electrocatalyst towards methanol oxidation and oxygen evolution reaction

“…Table 3 reveals that NiPR/ITO electrode exhibits lower onset voltage and higher oxidation current density towards methanol oxidation than earlier reported works. 60,70,74 The enhanced electrocatalytic activity can be explained using the following facts: (a) the high electrocatalytic activity of NiO and its conversion to NiOOH that acts as the active sites for combination of methanol; (b) the porous structure of NiPR nanocomposite is beneficial for methanol diffusion during the reaction; (c) the NiPR nanocomposite has high specific surface area owing to the both nanoplate and nanorod-like structures of NiO, which enable it to act as an excellent methanol oxidation catalyst in the alkaline solution; (d) in onedimensional nanorod structure, the transfer of charge between electrode and active sites is enhanced and (e) the large surface area of rGO present in NIPR catalyst enhances the adsorption of methanol molecules while the excellent electrical conductivity of rGO favours the good electrocatalytic activity of the electrode.…”