Operando Reconstruction toward Dual‐Cation‐Defects Co‐Containing NiFe Oxyhydroxide for Ultralow Energy Consumption Industrial Water Splitting Electrolyzer

Abstract

1987, Corrigan discovered a trace amount of Fe doped nickel oxide electrode can significantly enhance the OER. [3] Since then, most of the unmodified NiFe (oxy) hydroxide has been gradually pushed to the forefront, yet its catalytic activity (today above overpotentials of 0.3 V at 100 mA cm −2 ) is still insufficient compared to the thresholds of economic viability predicted by techno-economic assessments. [4] Tuning the oxygenated intermediates adsorption of the OER process by manipulating the electronic structure of the active site is crucial to further improve catalytic performance, which would render NiFe-based industrial water splitting electrolyzers more competitive. [5] Vacancy engineering, especially for metal cation vacancies with multifarious electron configuration and orbit has been implemented for enhancing OER activities via manipulating the energy band structure, carrier concentration, and spin state. [6] Beyond that, recent reports indicate that atomic cation-vacancy can improve the lattice bond energy in NiFe (oxy) hydroxide and thus inhibit Fe ion leaching to enhance the stability during OER. [7] However, as vacancies are introduced and concentrations increase, the catalyst structure will tend to be destroyed and its electrical conductivity will Nickel-iron oxygen evolution catalysts have been under the spotlight as substitutes for precious metals, however, they rarely operate efficiently in practical industrial electrolyzers due to their moderate activity. Guided by density functional theory, the interaction of cation vacancies and dopants can manipulate d band centers, thus gaining near-optimal binding energies of the oxygenated intermediates and ultralow potentials. This principle is implemented experimentally by catalysis operando variations synthesis, more specifically, in situ Mo leaching from high-entropy Co, Mo co-doped NiFe hydroxide precursors form Co dopant and cation vacancy coexistent NiFe oxyhydroxide. Operando electrochemical spectroscopy uncovers that dual-cation-defects promote the readier oxidation transition of metal sites, thus contributing to a low overpotential of 255 mV at 100 mA cm −2 . Furthermore, dual-regulated NiFe oxyhydroxide electrodes operate stably at 8 A in practical industrial electrolyzers with ultralow energy consumption of ≈4.6 kWh m −3 H 2 , verifying the feasibility of lab-constructed novel catalysts towards industrialization.

Fundamental Understanding of Structural Reconstruction Behaviors in Oxygen Evolution Reaction Electrocatalysts

“…Electrochemical water splitting to produce hydrogen fuel has been recognized as a highly promising technology for storing zero-carbon electricity generated from intermittent and nondispatchable renewable energy sources. [1][2][3][4][5] Generally, the water DOI: 10.1002/aenm.202301391 splitting technology comprises two half reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Unlike the HER which involves a relatively straightforward twoelectron transfer step, the OER is a more complex process that requires fourelectron transfer steps.…”

Synergistic Effect of N‐NiMoO4/Ni Heterogeneous Interface with Oxygen Vacancies in N‐NiMoO4/Ni/CNTs for Superior Overall Water Splitting

“…This may lead to the negative shift of Ni 2+ by gaining electrons. [50] More importantly, this process will lead to more Ni exposed to the surface and thereby explain why the HER activity of N-NiMoO 4 /Ni/CNTs is enhanced.…”

Low-temperature molten salt synthesis and catalytic mechanism of CoS2/NC as an advanced bifunctional electrocatalyst

“…The Tafel slopes of CoS 2 , CoS 2 /NC and commercial IrO 2 were 217, 172 and 171 mV dec −1 , respectively, indicating that the CoS 2 /NC composite exhibits excellent OER activity. 40 The double-layer capacitance ( C dl ) was evaluated through CV (Fig. S2†).…”