Chemically Deposited Amorphous Zn-Doped NiFeO_xH_y for Enhanced Water Oxidation

Abstract

Although NiFeO x H y has attracted enormous attention as an alkaline water electrolyzer owing to its high performance in the oxygen evolution reaction (OER), it still requires further improvement in terms of catalytic activity, durability, and an underlying understanding of the mechanism. Here we report the fabrication of Zn-doped NiFeO x H y (Zn;NiFeO x H y ) that has advanced electrocatalytic activity and stability in comparison to pure NiFeO x H y in the OER via simple chemical bath deposition and electrochemical activation. The improvement with Zn;NiFeO x H y is due to the Zn2+ dopant, a strong Lewis acid that modulates its electronic property for better intermediate binding for the electrochemical process, resulting in the stabilization of the OER-active phase. This work opens up an opportunity to elucidate the detailed mechanism of NiFeO x H y -based electrocatalysts and improves our understanding of redox tuning through inductive effects, thereby leading to advanced OER catalyst developments.

A Glass‐Ceramic with Accelerated Surface Reconstruction toward the Efficient Oxygen Evolution Reaction

“…The onset potential of Ni oxidation peak gradually decreases (inset of Figure 2 a), accompanying the cathodic peak shifts negatively (Δ E P,C =−94 mV), which suggest that the active species (Ni 3+ ) form at a lower potential [28] . It was reported that the phosphates can be easily exchanged with hydroxide anions [3a, 29] . As for pure amorphous triMPO 4 (Figure 2 b), both the cathodic peak shift (Δ E P,C =−34 mV) and the onset potential of Ni oxidation peak shift become smaller than those of glass‐ceramic under the same conditions.…”

“…Recent studies reported that cations or anions in catalysts could leach into the electrolyte under alkaline OER conditions, for examples, Sn 4+ leaching from CoSn 2, [31] CoSn(OH) 6 [32] and SnNiFe hydroxide perovskite, [33] Zn 2+ leaching from Zn‐Ni‐Co spinel oxides, [34] and F − leaching from NiFe‐OH‐F [16] . In addition, phosphates can be easily exchanged with hydroxide anions during the electrochemical process [3a, 8a] . Generally, the ion leaching behaviors can trigger favorable OH − adsorption on catalyst surface to accelerate the OER [13b]…”

“…Therefore, the development of efficient and durable earth‐abundant OER catalysts to replace precious metal oxides (e.g., IrO x and RuO 2 ) is essential for the commercialization of practically viable water splitting devices [3] . Currently, considerable efforts have been devoted to developing non‐precious OER electrocatalysts, including transition metal oxides, [4] layered double hydroxides (LDHs), [5] oxyhydroxide, [3a, 6] sulfides, [7] and pnictides [8] . Nevertheless, there is much room for the activity improvement by rationally designing and optimizing the micro‐nano structures and compositions of the electrocatalysts.…”

Non-redox doping boosts oxygen evolution electrocatalysis on hematite

“…67,68 Very recently, the positive effect of Zndoping on OER activity in alkaline media has been independently reported for the case of NiFeO x H y . 69 Of course, optimum doping levels and mechanistic considerations will depend on the structure and electronics of other host matrices. Such studies are in progress.…”

Efficient Water Splitting Actualized through an Electrochemistry‐Induced Hetero‐Structured Antiperovskite/(Oxy)Hydroxide Hybrid

“…It has been demonstrated that metal (oxy)hydroxides serve as promising OER catalysts. [ 14 ] Accordingly, we deduce that the rational design of antiperovskite/(oxy)hydroxide hybrid with abundant active sites and high conductivity may offer an opportunity for the application of water splitting. However, due to the demanding conditions required for heterostructure synthesis, [ 15 ] a simple synthetic process for antiperovskite/(oxy)hydroxide hybrid system is greatly valuable.…”