Unusual Effect of Trace Water on the Structure and Activity of Ni_xCo_1−x Electrocatalysts for the Methanol Oxidation Reaction

Abstract

Highly active Ni‐based catalysts have attracted much attention but are still facing challenges owing to the immature synthetic method. Herein, polyhedral NixCo1−x alloy was prepared by a facile modified polyol method in which a trace amount of water could halve the particle size of the alloy. The Ni/Co ratios in NixCo1−x alloy strictly depended on the used amount of water owing to the different solubilities of the precursors. Among them, the Ni0.6Co0.4 nanoparticles obtained with 70 μL of deionized water exhibited the best performance in the methanol oxidation reaction with a peak current density of 116 mA cm−2 in the presence of 1 m NaOH+0.5 m CH3OH solution, which is higher than those of Ni0.7Co0.3 (80 mA cm−2) and Ni0.5Co0.5 (33 mA cm−2). The excellent performance of Ni0.6Co0.4 is attributed to the unique structure with appropriate Ni/Co ratio, which elongates the C−O bond in methanol and lowers the reaction free energy according to DFT calculations.

Acid-Etched Co3O4 Nanoparticles on Nickel Foam: The Highly Reactive (311) Facet and Enriched Defects for Boosting Methanol Oxidation Electrocatalysis

“…However, Co 3 O 4 NP/NF not only showed a relatively large ECSA but also an obvious high specific activity converted from the ECSA, suggesting that there were a superior intrinsic activity and a strong ability to activate the methanol molecules and reduce the (CO) ads on the surface of the catalysts. 13,14,43,44 It is further demonstrated by CO-stripping voltammograms in Figure S11. For Co 3 O 4 NP/NF, the CO electro-oxidation peak appears at a more negative potential, which also shows the highest peak current density, indicating the preference of CO oxidative desorption.…”

Recent Advances in Bio‐Templated Metallic Nanomaterial Synthesis and Electrocatalytic Applications

“…However, despite their potential advantages, DAFCs generally have slow kinetics [223] . In addition, various intermediates such as CO, aldehyde could be strongly adsorbed on the electrode surface and poison the active sites of the Pt catalyst [224] . It is thus vital to develop materials with fast kinetics and high durability.…”

“…Pd‐based materials have been found to show higher activity than Pt‐based catalysts towards EOR in alkaline conditions [224,225] . Controllable synthesis of Pd NMs with well‐defined morphology and size is thus beneficial to construct anode material.…”

Tuning the Electronic Structures of TMNs‐Modified Ni‐Based Catalysts to Enhance the Performance for MOR in Alkaline Media

“…Compared with the monometallic catalyst, previous studies have shown that the bimetallic alloy Ni-based catalysts can improve the electrocatalytic activity for methanol oxidation reaction. [14][15][16][17][18] Li et al [19] synthesized the bimetallic NiSn nano-catalysts with 3-5 nm particle size by adjusting the Ni/Sn ratio. The electrochemical results showed that the interaction between Ni and Sn could improve the electrocatalytic activity for MOR.…”

“…As we all know, introduction the appropriate second metal or components can modify the electronic structures of the active metals and further improve the catalytic performance. Compared with the monometallic catalyst, previous studies have shown that the bimetallic alloy Ni‐based catalysts can improve the electrocatalytic activity for methanol oxidation reaction [14–18] . Li et al [19] .…”