Engineering Self‐Reconstruction via Flexible Components in Layered Double Hydroxides for Superior‐Evolving Performance

Abstract

Most transition metal‐based catalysts for electrocatalytic oxygen evolution reaction (OER) undergo surface reconstruction to generate real active sites favorable for high OER performance. Herein, how to use self‐reconstruction as an efficient strategy to develop novel and robust OER catalysts by designing pre‐catalysts with flexible components susceptible to OER conditions is proposed. The NiFe‐based layered double hydroxides (LDHs) intercalated with resoluble molybdate (MoO42−) anions in interlayers are constructed and then demonstrated to achieve complete electrochemical self‐reconstruction (ECSR) into active NiFe‐oxyhydroxides (NiFeOOH) beneficial to alkaline OER. Various ex situ and in situ techniques are used to capture structural evolution process including fast dissolution of MoO42− and deep reconstruction to NiFeOOH upon simultaneous hydroxyl invasion and electro‐oxidation. The obtained NiFeOOH exhibits an excellent OER performance with an overpotential of only 268 mV at 50 mA cm−1 and robust durability over 45 h, much superior to NiFe‐LDH and commercial IrO2 benchmark. This work suggests that the ECSR engineering in component‐flexible precursors is a promising strategy to develop highly active OER catalysts for energy conversion.

Chameleon‐Like Reconstruction on Redox Catalysts Adaptive to Alkali Water Electrolysis

“…[ 22,23 ] In order to further understand reconstruction mechanism and apply reconstruction engineering, much effort has recently been devoted to capture real‐time reconstruction dynamics with advanced operando techniques and steer reconstruction direction/degree by selective pre‐catalysts or electrochemical conditions. [ 24–28 ] For example, Liu et al. discovered the dynamic reconstruction over nickel molybdate hydrate pre‐catalysts via cyclic voltammetry (CV) measurement under alkaline OER condition, [ 24 ] which spotlights the significance of deep/complete reconstruction to maximize active sites.…”

“…[ 25 ] More recently, our research group also designed the nickel‐iron layered hydroxides intercalated with resoluble molybdate anions in interlayers to demonstrate a complete self‐reconstruction into active nickel‐iron (oxy)hydroxides for favorable OER in alkaline media. [ 28 ] In particular, an interesting chameleon‐like reconstruction via electro‐oxidation was disclosed by Cao et al. on cobalt sulfide pre‐catalysts sensitive to the neutral and alkaline media using operando X‐ray spectroscopy.…”

“…[22,23] In order to further understand reconstruction mechanism and apply reconstruction engineering, much effort has recently been devoted to capture real-time reconstruction dynamics with advanced operando techniques and steer reconstruction direction/degree by selective pre-catalysts or electrochemical conditions. [24][25][26][27][28] For example, Liu et al discovered the dynamic reconstruction over nickel molybdate hydrate pre-catalysts via cyclic voltammetry (CV) measurement under alkaline OER condition, [24] which spotlights the significance of deep/complete reconstruction to maximize active sites. Wang et al recently achieved a rapid and deep self-reconstruction toward targeted nickel-iron (oxy)hydroxides as highly active OER catalysts via a creative design of multicomponent nanowire pre-catalysts enabling with fast anion etching and simultaneous cation incorporation at oxidized potentials.…”

“…[25] More recently, our research group also designed the nickel-iron layered hydroxides intercalated with resoluble molybdate anions in interlayers to demonstrate a complete self-reconstruction into active nickeliron (oxy)hydroxides for favorable OER in alkaline media. [28] In particular, an interesting chameleon-like reconstruction via electro-oxidation was disclosed by Cao et al on cobalt sulfide Pre-catalyst reconstruction in electrochemical processes has recently attracted intensive attention with mechanistic potentials to uncover really active species and catalytic mechanisms and advance targeted catalyst designs. Here, nickel-molybdenum oxysulfide is deliberately fabricated as precatalyst to present a comprehensive study on reconstruction dynamics for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkali water electrolysis.…”

Defect-rich Fe-doped NiS/MoS2 heterostructured ultrathin nanosheets for efficient overall water splitting

“…Electrooxidation of Ni compounds is commonly observed in OER catalysis, and the resultant NiOOH/Ni(OH) 2 is highly active with a long-term OER stability. [43][44][45] After 1000 OER cycles, the nanosheet morphology of the material is retained, except for a slight aggregation (Fig. S5b and c, ESI †).…”