Metallic Gold-Incorporated Ni(OH)₂ for Enhanced Water Oxidation in an Alkaline Medium: A Simple Wet-Chemical Approach

Abstract

The development of a highly efficient electrocatalyst for the oxygen evolution reaction (OER) with a lower overpotential and high intrinsic activity is highly challenging owing to its sluggish kinetic behavior. As an alternative to the state-of-the-art OER catalyst, recently, transition-metal-based hydroxide materials have been shown to play important roles for the same. Owing to the high earth abundance of various Ni-based hydroxide and its derivatives, these are known to be highly studied materials for the OER. Herein, we report a simple wet-chemical synthesis of metallic gold-incorporated (by varying the concentration of Au3+ ions) Ni­(OH)2 nanosheets as an active and stable electrocatalyst for the OER in 1 M KOH medium. The Au-Ni­(OH)2 (2) catalyst demanded a low overpotential of 288 mV to attain a geometric current density of 10 mA/cm2 with a lower Tafel value of 55 mV/dec compared to bare Ni­(OH)2 with a lower mass loading of only 0.1 mg/cm2. Tafel slope analysis reveals that the incorporation of metallic gold on the hydroxide surfaces could alter the mechanistic pathways of the overall OER reaction. It has been proposed that the incorporation of metallic gold over the Ni­(OH)2 surfaces led to a change in the electronic structure of the electroactive nickel sites (Jahn–Teller distortion), which favors the OER by electronic aspects.

Vanadium-Doped Nickel Cobalt Layered Double Hydroxide: A High-Performance Oxygen Evolution Reaction Electrocatalyst in Alkaline Medium

“…Since the ligand field of the metallic component is fully based on the weak field OH – ions, we are assuming that all of the octahedral entities are present in high-spin configuration. As it is well known, the presence of Ni in the +3 oxidation state would always favor the OER with a lower applied potential . Besides the presence of the Ni 3+ ions, the presence of Ni 2+ ions can synergistically participate in electronic interaction with other ions, especially in the case of the LDH system.…”

“…As it is well known, the presence of Ni in the +3 oxidation state would always favor the OER with a lower applied potential. 67 Besides the presence of the Ni 3+ ions, the presence of Ni 2+ ions can synergistically participate in electronic interaction with other ions, especially in the case of the LDH system. Here, in NiCo-LDH, the cobalt ions are present in +2 and +3 oxidation states.…”

Tuning the Electronic Structure of a Ni-Vacancy-Enriched AuNi Spherical Nanoalloy via Electrochemical Etching for Water Oxidation Studies in Alkaline and Neutral Media

“…The availability of a vacant d x 2 – y 2 orbital could offer a vacant orbital (LUMO) toward the incoming OH – ions (HOMO) during the OER . Also, from the mechanistic point of view, the creation of a Ni vacancy led to alteration of the rate-determining step (RDS) of the overall reaction.…”

“…The availability of a vacant d x 2 −y 2 orbital could offer a vacant orbital (LUMO) toward the incoming OH − ions (HOMO) during the OER. 81 catalysts is shown in Figure 10. The presence of S and N will definitely play an important role in deciding the electrochemical outcomes of alloys.…”

Rationally Constructing Chalcogenide–Hydroxide Heterostructures with Amendment of Electronic Structure for Overall Water-Splitting Reaction

“…In this regard, the transition metal (TM)-based sulfides, selenides, and phosphides are employed as promising electrocatalysts for HER, and copious efforts have been made to improve the HER performance. ,− Among them, transition metal sulfides show high activities, which might be due to the presence of unsaturated metal sites, and low intrinsic resistivities with high stabilities toward HER . Also, for OER, the transition metal-based oxides, chalcogenides, hydroxides, and layered double hydroxides (LDHs) are considered as highly active electrocatalysts. − Among the aforementioned catalysts, nickel-based LDHs exhibit higher catalytic activities toward water-splitting reactions in an alkaline electrolyte solution. − Recently, a NiV-monolayer double hydroxide shows better activity with 350 mV as the overpotential to attain a 27 mA cm –2 current density which was lower than the pristine NiFe-LDH catalyst . However, to attain high performance toward overall water splitting, the use of same catalyst for OER as well as for HER is facing a huge challenge in alkaline media.…”