Efficacy analysis of compartmentalization for ambient CH(4) activation mediated by a Rh(II) metalloradical in a nanowire array electrode

Compartmentalization is a viable approach for ensuring the turnover of a solution cascade reaction with ephemeral intermediates, which may otherwise deactivate in the bulk solution. In biochemistry or enzyme-relevant cascade reactions, extensive models have been constructed to quantitatively analyze the efficacy of compartmentalization. Nonetheless, the application of compartmentalization and its quantitative analysis in non-biochemical reactions is seldom performed, leaving much uncertainty about whether compartmentalization remains effective for non-biochemical reactions, such as organometallic, cascade reactions. Here, we report our exemplary efficacy analysis of compartmentalization in our previously reported cascade reaction for ambient CH(4)-to-CH(3)OH conversion, mediated by an O(2)-deactivated Rh(II) metalloradical with O(2) as the terminal oxidant in a Si nanowire array electrode. We experimentally identified and quantified the key reaction intermediates, including the Rh(II) metalloradical and reactive oxygen species (ROS) from O(2). Based on such findings, we experimentally determined that the nanowire array enables about 81% of the generated ephemeral intermediate Rh(II) metalloradical in air, to be utilized towards CH(3)OH formation, which is 0% in a homogeneous solution. Such an experimentally determined value was satisfactorily consistent with the results from our semi-quantitative kinetic model. The consistency suggests that the reported CH(4)-to-CH(3)OH conversion surprisingly possesses minimal unforeseen side reactions, and is favorably efficient as a compartmentalized cascade reaction. Our quantitative evaluation of the reaction efficacy offers design insights and caveats into application of nanomaterials to achieve spatially controlled organometallic cascade reactions.