Magnetically tunable selectivity in methane oxidation enabled by Fe-embedded liquid metal catalysts
Haoran Zhang, Yinhe Wang, Yu Zhang, Fan Wu, Rui Huang, Sicong Wang, Xiaokang Liu, Yihua Ran, Zhiwen Zhang, Jun Cai, Zhou Huang, Tao Yao, Jun Jiang, Zhi Liu, Yu Mao, Weijie Zhong, Lin Hu, Lei Zheng, Yuen Wu
Abstract
As they are liquids at room temperature, gallium-based metal substrates allow catalytic metal atoms to move freely without lattice constraints, thereby facilitating the development of catalysts with reconfigurable structures. Here we design an iron-embedded liquid metal catalyst that enables reversible switching of the aggregation and electron spin of iron atoms by controlling an external magnetic field. This facilitates a reversible conversion of the primary liquid products, methyl hydroperoxide (CH3OOH) and acetic acid (CH3COOH), under ambient conditions. The catalyst achieves promising production rates (CH3OOH, 1,679.6 $${\rm{m}}{\rm{m}}{\rm{o}}{\rm{l}}\,{{\rm{g}}}_{{\rm{F}}{\rm{e}}}^{-1}\,{{\rm{h}}}^{-1}$$ ; CH3COOH, 790.5 $${\rm{m}}{\rm{m}}{\rm{o}}{\rm{l}}\,{{\rm{g}}}_{{\rm{F}}{\rm{e}}}^{-1}\,{{\rm{h}}}^{-1}$$ ) and high selectivities (CH3OOH, 99.9%; CH3COOH, 91.7%). In the absence of the magnetic field, iron atoms are atomically dispersed, leading to the C1 pathway without C–C bond coupling. When a magnetic field is applied, iron atoms cluster, favouring CH3COOH production in the C2 pathway. The product distribution can be finely and reversibly tuned with magnetic field intensity adjustments ranging from 0 to 500 G. Our findings highlight the potential for using an external magnetic field to precisely control catalytic pathways. A gallium-based, iron-embedded liquid metal catalyst enables reversible, magnetic-field-controlled switching between atomically dispersed and clustered iron states, achieving tunable production of CH₃OOH and CH₃COOH under ambient conditions.