Low-valent Mo single atoms stabilized by electronegative oxygen coordination enable efficient water oxidation.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen evolution reaction (OER) is kinetically limited, hindering efficient energy conversion.
• Low-valent single-atom catalysts coordinated with electronegative atoms are crucial for OER.
• Layered double hydroxides (LDHs) and oxyhydroxides offer promising matrices for catalyst anchoring.

Purpose of the Study:

• To rationally design and synthesize low-valent molybdenum single atoms (Mo SAs) anchored on NiFe LDH.
• To investigate the catalytic activity and stability of the resulting ^LSAMo-NiFe LDH for OER.
• To elucidate the underlying mechanism and optimize the catalyst for high-performance electrocatalysis.

Main Methods:

• Low-temperature solution-phase reduction for anchoring Mo SAs onto NiFe LDH.
• Electrochemical testing in alkaline media to evaluate OER performance.
• Operando electrochemical characterization and theoretical calculations to study the reaction mechanism.

Main Results:

• ^LSAMo-NiFe LDH exhibited superior intrinsic activity compared to pristine NiFe LDH and IrO₂.
• A 3D monolithic electrode achieved an ultra-low overpotential of 158 mV at 10 mA cm^-2.
• The catalyst demonstrated excellent stability, retaining its atomic structure after prolonged operation.

Conclusions:

• Low-valent Mo SAs synergistically enhance OER activity through electronic interactions with the NiFe LDH lattice.
• The lattice oxygen mechanism is the primary pathway for OER on this catalyst.
• This work provides a universal strategy for designing high-performance, low-valent single-atom catalysts.