A Spin Descriptor Map Predicts NiFe₂O₄ for Efficient Electrosynthesis of Cyclohexanone Oxime

Area of Science:

• Electrocatalysis
• Surface Chemistry
• Computational Chemistry

Background:

• Selective hydrogenation of nitric oxide (NO) to hydroxylamine (NH2OH) is crucial for cyclohexanone oxime electrosynthesis.
• The role of spin state transitions in NO hydrogenation pathways has been overlooked.

Purpose of the Study:

• To investigate the impact of spin state transitions on NO hydrogenation selectivity.
• To propose a spin locking mechanism for enhancing electrosynthesis performance.
• To identify key descriptors for catalyst screening.

Main Methods:

• Density functional theory (DFT) calculations.
• Sure independence screening and sparsifying operator (SIS) for feature selection.
• In situ spectroscopy for experimental validation.

Main Results:

• Medium spin states stabilize the *NHO intermediate by locking NO spin configuration.
• Weakened *NH2OH adsorption is achieved, enhancing selectivity.
• Predictive metrics (µS·θ)³ and (cos θ/q) were developed for catalyst screening.
• NiFe2O4 was identified as a promising catalyst, achieving 70% Faradaic efficiency.

Conclusions:

• Spin regulation is critical for controlling selectivity in electrosynthesis.
• The proposed spin locking mechanism offers a new strategy for catalyst design.
• Computational screening metrics can effectively predict catalyst performance.