Boosting Electrocatalytic Water Oxidation by Creating Defects and Lattice‐Oxygen Active Sites on Ni‐Fe Nanosheets

Wang

et al. 2021

Small

challenge and can provide an adequate pathway to store renewable energy in the form of hydrogen fuel. [2] Oxygen evolution reaction (OER) is however a half-reaction that largely limits the efficiency of water splitting, as emphasized in fundamental catalysis recently, [3] where the multiple electron-proton coupled transfer steps of the OER process often lead to sluggish kinetics and high overpotentials, and therefore limit the device performance at increased operating costs. [4,5] There is therefore an urgent need for high-performance electrocatalysts to reduce the energy barrier and accelerate the catalytic reaction to improve the overall energy conversion efficiency. In general, the currently known state-of-the-art electrolysis technology requires the use of Ru/Ir-based electrocatalysts as the OER electrodes. [6] However, the high cost of these precious metals apparently impedes their largescale applications. [7,8] On the other hand, although transition metal compounds (TMC) with earth abundance, multifunctional redox valence, and unsaturated transition metal sites have been widely studied, their inherently poor activity and unsatisfactory long term stability need to be further improved. [9][10][11] The development of highly active and durable electrocatalysts is therefore of great significance for accelerating the application of OER.The electrochemical oxygen evolution reaction (OER) by efficient catalysts is a crucial step for the conversion of renewable energy into hydrogen fuel, in which surface/near-surface engineering has been recognized as an effective strategy for enhancing the intrinsic activities of the OER electrocatalysts. Herein, a facile quenching approach is demonstrated that can simultaneously enable the required surface metal doping and vacancy generation in reconfiguring the desired surface of the NiCo 2 O 4 catalyst, giving rise to greatly enhanced OER activities in both alkaline freshwater and seawater electrolytes. As a result, the quenched-engineered NiCo 2 O 4 nanowire electrode achieves a current density of 10 mA cm −2 at a low overpotential of 258 mV in 1 m KOH electrolyte, showing the remarkable catalytic performance towards OER. More impressively, the same electrode also displays extraordinary activity in an alkaline seawater environment and only needs 293 mV to reach 10 mA cm −2 . Density functional theory (DFT) calculations reveal the strong electronic synergies among the metal cations in the quench-derived catalyst, where the metal doping regulates the electronic structure, thereby yielding near-optimal adsorption energies for OER intermediates and giving rise to superior activity. This study provides a new quenching method to obtain high-performance transition metal oxide catalysts for freshwater/seawater electrocatalysis.

Section: Introductionmentioning

confidence: 99%

Quench‐Induced Surface Engineering Boosts Alkaline Freshwater and Seawater Oxygen Evolution Reaction of Porous NiCo₂O₄ Nanowires

Wang

et al. 2021

Small

Advanced Energy Materials

“…This defect‐rich structure required an overpotential of 172 mV to obtain the current density of 10 mA cm −2 . [ 113 ] The presence of defects on the electrocatalyst surface suggests the influence of mesoscale diffusion control. In the case of the NiFe LDHs electrocatalyst, which is obtained from NFF through a self‐growth method, it exhibited dynamic changes in surface morphology due to the presence of Ni vacancies.…”

Section: Fabrication Of Self‐supported Fe‐based Oer Electrocatalystsmentioning

confidence: 99%

Self‐Supported Fe‐Based Nanostructured Electrocatalysts for Water Splitting and Selective Oxidation Reactions: Past, Present, and Future

Gaikwad,

Burungale,

Malavekar

et al. 2024

Electrochemical water splitting plays a vital role in facilitating the transition towards a sustainable energy future by enabling renewable hydrogen (H2) production, energy storage, and emission‐free transportation. Developing earth‐abundant electrocatalysts with outstanding overall water‐splitting performance, excellent catalytic activity, and robust long‐term stability is highly important in the practical application of water electrolysis. Self‐supported electrocatalysts have emerged as the most appealing candidate for practical H2 production due to their increased active site loading, rapid mass and charge transfer, and strong interaction with the underneath conducting support. Additionally, these electrocatalysts also provide enhanced reaction kinetics and stability. Here, a comprehensive review of recent progress in developing self‐supported Fe‐based electrocatalysts for water splitting and selective oxidation reactions is presented with examples of oxyhydroxides, layered double hydroxides, oxides, chalcogenides, phosphides, nitrides, and other Fe‐containing electrocatalysts. A comprehensive historical development in the synthesis of self‐supported Fe‐based electrocatalysts is provided, with an emphasis on the various deposition methods and the choice of self‐supported conducting substrates considering large‐scale commercial applications. An overview of mechanistic understanding and approaches for enhanced H2 production are also presented. Finally, the challenges and opportunities associated with developing Fe‐based electrocatalysts for practical applications in water splitting and alternative oxidation reactions are discussed.

“…The cooperative interaction between Ni and Fe toward OER catalysis was also realized by doping Fe into Ni(OH) 2 , which offers a more tunable and simpler system compared with NiFe-LDHs. [6][7][8][9] Recently, Kou et al reported that a direct reaction of Fe(NO 3 ) 3 with Ni foam (Ni 0 + NO 3 À + H + ! Ni 2+ + NO 2 À + OH À ) could produce ultrathin Fe-doped Ni(OH) 2 nanosheets that showed further boosted OER activities with a low (0.54 at %) Fe doping.…”

Section: Introductionmentioning

confidence: 99%

Surface modulated Fe doping of β‐Ni(OH)₂ nanosheets for highly promoted oxygen evolution electrocatalysis

Kim

et al. 2022

EcoMat

Active yet low‐cost electrocatalysts for water oxidation are crucial for the development of hydrogen energy economy. The Fe doping into Ni(OH)2 dramatically enhances catalytic activity toward oxygen evolution reaction (OER) but fabricating Ni(OH)2 of high Fe loading is still challenging. Herein, we report a one‐pot strategy to prepare disordered β‐Ni(OH)2 nanosheets with a high Fe doping level (9.9 at%, D‐Fe‐Ni(OH)2). By engaging 1,4‐phenylenediphosphonic acid (BDPA), FexBDPAy precursors are in situ generated in a growth solution containing Fe3+ ions, which decrease the reaction kinetics of Ni2+ and Fe3+ ions at the surface of Ni foam. This prevents the deconstructive hydrolysis by Fe3+ ions and enables a high Fe‐doping in D‐Fe‐Ni(OH)2. The as‐prepared D‐Fe‐Ni(OH)2 affords 10 mA cm−2 at an ultralow OER overpotential of 194 mV in alkaline media. This work offers a promising strategy of engaging organic ligands to achieve high‐doping levels for the construction of efficient electrocatalysts.