Efficacy Analysis of Compartmentalization for Ambient CH4 Activation Mediated by RhII Metalloradical in Nanowire Array Electrode

<p>Compartmentalization is a viable approach of 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 seldomly performed, leaving much uncertainty about whether compartmentalization remains effective for non-biochemical, such as organometallic, cascade reactions. Here, we report our exemplary efficacy analysis of compartmentalization in our previously reported cascade reaction for ambient CH4-to-CH3OH conversion, mediated by O2-deactivating RhII metalloradical with O2 as the terminal oxidant in Si nanowire array electrode. We experimentally identified and quantified the productivity of key reaction intermediates, including RhII metalloradical and reactive oxygen species (ROS) from O2. We subsequently determined that the nanowire array enables about 81 % of the generated ephemeral intermediate in air, RhII metalloradical, to be utilized towards CH3OH formation, which is 0% in homogenous solution. Such an experimentally determined value was satisfactorily consistent with the results from our semi-quantitative kinetic model. The consistency suggests that the reported CH4-to-CH3OH 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 a spatially controlled organometallic cascade reactions.</p>

Efficacy Analysis of Compartmentalization for Ambient CH4 Activation Mediated by RhII Metalloradical in Nanowire Array Electrode

<p>Compartmentalization is a viable approach of 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 seldomly performed, leaving much uncertainty about whether compartmentalization remains effective for non-biochemical, such as organometallic, cascade reactions. Here, we report our exemplary efficacy analysis of compartmentalization in our previously reported cascade reaction for ambient CH4-to-CH3OH conversion, mediated by O2-deactivating RhII metalloradical with O2 as the terminal oxidant in Si nanowire array electrode. We experimentally identified and quantified the productivity of key reaction intermediates, including RhII metalloradical and reactive oxygen species (ROS) from O2. We subsequently determined that the nanowire array enables about 81 % of the generated ephemeral intermediate in air, RhII metalloradical, to be utilized towards CH3OH formation, which is 0% in homogenous solution. Such an experimentally determined value was satisfactorily consistent with the results from our semi-quantitative kinetic model. The consistency suggests that the reported CH4-to-CH3OH 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 a spatially controlled organometallic cascade reactions.</p>

A Novel Dry Selective Isotropic Atomic Layer Etching of SiGe for Manufacturing Vertical Nanowire Array with Diameter Less than 20 nm

Semiconductor nanowires have great application prospects in field effect transistors and sensors. In this study, the process and challenges of manufacturing vertical SiGe/Si nanowire array by using the conventional lithography and novel dry atomic layer etching technology. The final results demonstrate that vertical nanowires with a diameter less than 20 nm can be obtained. The diameter of nanowires is adjustable with an accuracy error less than 0.3 nm. This technology provides a new way for advanced 3D transistors and sensors.

Fabrication and Field-Emission Properties of Vertically-Aligned Tapered [110]Si Nanowire Arrays Prepared by Nanosphere Lithography and Electroless Ag-Catalyzed Etching

In this study, the controllable fabrication of a variety of vertically aligned, single-crystalline [110]-oriented Si nanowire arrays with sharp tips on (110)Si substrates is achieved using a combined self-assembled nanosphere lithography and multiple electroless Ag-catalyzed Si etching processes. All of the experiments were performed at room temperature. The morphological evolution and formation mechanism of long tapered [110]Si nanowire arrays during the multiple tip-sharpening cycle processes have been investigated by scanning electron microscopy, transmission electron microscopy and water contact angle measurements. Field emission measurements demonstrate that the field-emission behaviors of all nanowire samples produced in this study agree well with the Fowler–Nordheim theory, and the produced long tapered [110]Si nanowire array possesses superior electron emission characteristics, with a very low turn-on field of 1.4[Formula: see text]V/[Formula: see text]m and a high field enhancement factor of 3816. The simple and room temperature fabrication of the well-ordered long tapered [110]Si nanowire array and its excellent electron field emission performance suggest that it can serve as a good candidate for applications in high-performance Si-based vacuum electronic nanodevices.