Boosting Benzene Oxidation with a Spin-State-Controlled Nuclearity Effect on Iron Sub-Nanocatalysts

A fundamental understanding of the nature of nuclearity effects is important for the rational design of superior sub-nanocatalysts with low nuclearity, but remains a long-standing challenge. Using atomic layer deposition, we precisely synthesized Fe sub-nanocatalysts with tunable nuclearity (Fe-1-Fe-4) anchored on N,O-co-doped carbon nanorods (NOC). The electronic properties and spin configuration of the Fe sub-nanocatalysts were nuclearity dependent and dominated the H2O2 activation modes and adsorption strength of active O species on Fe sites toward C-H oxidation. The Fe-1-NOC single atom catalyst exhibits state-of-the-art activity for benzene oxidation to phenol, which is ascribed to its unique coordination environment (Fe1N2O3) and medium spin state (t(2g)(4)e(g)(1)); turnover frequencies of 407 h(-1) at 25 degrees C and 1869 h(-1) at 60 degrees C were obtained, which is 3.4, 5.7, and 13.6 times higher than those of Fe dimer, trimer, and tetramer catalysts, respectively.

Automated summary

A profound understanding of the nature of nuclearity effects is crucial for designing high-performance sub-nanocatalysts with low nuclearity, yet it remains a longstanding challenge. By employing atomic layer deposition, we precisely synthesized Fe sub-nanocatalysts with adjustable nuclearity (Fe-1-Fe-4) immobilized on N,O-co-doped carbon nanorods (NOC). The nuclearity-dependent electronic properties and spin configuration of the Fe sub-nanocatalysts dominate the activation modes of H2O2 and the adsorption strength of active O species on Fe sites for C-H oxidation.