Highly Branched Metal Alloy Networks with Superior Activities for the Methanol Oxidation Reaction

Abstract

Three-dimensional (3D) interconnected metal alloy nanostructures possess superior catalytic performance owing to their advantageous characteristics, including improved catalytic activity, corrosion resistance, and stability. Hierarchically structured Ni-Cu alloys composed of 3D network-like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution-assisted electrodeposition approach. They were subsequently exploited for methanol electrooxidation in alkaline media. Among three hierarchically structured Ni-Cu alloys with different Ni/Cu ratios (Ni Cu , Ni Cu , and Ni Cu ), the Ni Cu electrode exhibited the fastest electrochemical response and highest electrocatalytic activity toward methanol oxidation. The markedly enhanced performance of Ni Cu eletrocatalyst can be attributed to its alloyed structure with the proper Ni/Cu ratio and a large number of active sites on the surface of hierarchical structures.

NiSn bimetallic nanoparticles as stable electrocatalysts for methanol oxidation reaction

“…The current densities largely dropped in the first minutes and then relatively stabilized. Similarly fast initial drops were previously observed [14] and are generally attributed to the fact that initially active sites are free of adsorbed methanol molecules and no methanol depletion layer around the electrode exist, allowing a very fast initial reaction. In the first minutes, an equilibrium coverage of methanol at the catalyst surface and an equilibrium gradient of methanol around case, no methanol depletion layer is formed and current densities do not suffer any initial drop.…”

“…Ni [7][8][9][10] and Nibased alloys reported to date, such as NiCu [11][12][13][14], NiFe [15], NiCo [16], NiMn [17] and NiTi [18,19] show excellent catalytic activities, but even in alkaline electrolytes, they lack of a satisfactory durability.…”

Unusual Effect of Trace Water on the Structure and Activity of NixCo1−x Electrocatalysts for the Methanol Oxidation Reaction

“…The binding energies of 852.6 and 869.7 eV can be assigned to Ni 2p 3/2 and Ni 2p 1/2 , respectively, which represent the chemical valence of Ni 0 at these two positions (Figure h). The Ni 2+ peaks and satellite peaks are located at 855.7, 873.5, and 861.5, 879.8 eV, respectively, in good agreement with the reported Ni 2+ binding energies . The peaks observed at 777.8 and 793.3 eV correspond to Co 2p 3/2 and Co 2p 1/2 and reflect that the chemical valence of Co is zero.…”

“…The Ni–MnO x /C nanoparticles synthesized by Abdel Hameed using a microwave‐assisted method exhibited several times higher catalytic performance than ordinary Ni/C . A layered Ni–Cu alloy network of composition Ni 0.75 Cu 0.25 with microscopically interconnected branches and nanoscale dendritic tentacles showed a peak current density of 84 mA cm −2 . The peak current density of Co–Ni/RGO synthesized by the traditional polyol method reached 22.5 mA cm −2 for a Co/Ni ratio of 1:4 .…”

Phase Modulating of Cu–Ni Nanowires Enables Active and Stable Electrocatalysts for the Methanol Oxidation Reaction

“…Figure a compares the I – t curves obtained for Cu 1 Ni 1 NWs/C (400 °C‐A/200 °C‐H) at three different applied potentials of +0.6, +0.7, and +0.8 V (vs. SCE) for 5 h. The current drops sharply at first and then decreases slightly for all kinds of catalysts. This is due to the fact that the active sites of the catalysts are free for adsorbing methanol at the beginning of the MOR reaction . Then with the electrochemical process going by, the intermediate species deposited on the catalysts may poison the active sites, leading to the decreased current .…”