Ni Foam-Supported Ni Nanoclusters for Enhanced Electrocatalytic Oxygen Evolution Reaction

Abstract

Developing oxygen evolution reaction (OER) electrocatalysts is essential to accomplish viable CO2 and water electrolysis. Herein, we report the fabrication and OER performance of Ni-foam (NF)-immobilized Ni6 nanoclusters (NCs) (Ni6/NF) prepared by a dip-coating process. The Ni6/NF electrode exhibited a high current density of 500 mA/cm<sup>2</sup> for the OER at an overpotential as low as 0.39 V. Ni6/NF exhibited high durability in an alkaline solution without corrosion. Electrokinetic studies revealed that OER can be easily initiated on Ni6 NC with fast electron-transfer rates. Finally, we demonstrated stable CO2-to-CO electroreduction using an NC-based zero-gap CO2 electrolyzer operated at a current density of 100 mA/cm<sup>2</sup> and a full-cell potential of 2.0 V for 12 h.

Atomically precise metal nanoclusters for energy conversion

“…34,58,68,69 This low performance (i.e., OER current) is mainly ascribed to the use of carbon supports, which are widely employed as electronic conductors but are vulnerable to corrosion under oxidation conditions. 70,71 In a recent study on Ni 6 NCs as OER electrocatalysts, 36 Ni foam-supported Ni 6 NCs (Ni 6 /NF) were fabricated using a simple dip-coating method (Figure 4e, left). Methanol, which does not dissolve Ni 6 (SEtPh) 12 NCs (SEtPh = 2-phenylethanethiolate) but acts as a good dispersion medium for the same, was used as the suspension medium to achieve the adherence of the NCs to the support.…”

“…OER currents of Ni 6 NCs reported elsewhere are shown for comparison. (g) Faradaic efficiency (FE) for O 2 production on various electrodes measured after electrolysis at 50 mA/cm 2 for 1 h. Reproduced with permission from Seong et al 36 Copyright 2023, The Korean Electrochemical Society.…”

A homologous series of macrocyclic Ni clusters: synthesis, structures, and catalytic properties

“…In particular, the synthesis of core-shell structured clusters is extremely challenging; instead, cyclic polynuclear, tiara-like Ni clusters are readily available. [18][19][20][21][22][23][24][25][26][27][28][29][30][31] The development of the cyclic polynuclear Ni 6 (SR) 12 clusters dates back to the 1960s. 18,19 Since then, nickel clusters have received increasing attention, probably because of their low price and availability of large reserves of nickel compared to platinum and palladium.…”

“…21,25,28,32 As a medium-sized cyclic nickel cluster, Ni 6 clusters stabilized by diverse ligands have been intensively studied. [18][19][20][21][22][23][24][25][26]33,34 For example, Woodward and co-workers reported the first representative of a Ni 6 cluster, which was obtained from the reaction of diethyl disulfide with nickel carbonyl in benzene. 18 Subsequently, cyclic Ni 6 clusters stabilized by other thiol ligands have also been reported, and in-depth investigations into their structure and properties conducted.…”

“…18 Subsequently, cyclic Ni 6 clusters stabilized by other thiol ligands have also been reported, and in-depth investigations into their structure and properties conducted. [19][20][21][22][23][24][25][26]33,34 In addition, smaller size nickel clusters such as Ni 4 and Ni 5 have also been prepared, and structure characterization results demonstrated that both have crown-like structures built up from approximately planar [NiS 4 ] units linked by bridged thiolate ligands. 27,[29][30][31][32]35 Such series of small-ring Ni n clusters (n = 4, 5, 6) are easy to prepare and display highly symmetric polygonal structures, probably because of their aromaticity.…”