Solution-Liquid-Solid Growth and Catalytic Applications of Silica Nanorod Arrays

Abstract

As an analogue to the vapor-liquid-solid process, the solution-liquid-solid (SLS) method offers a mild solution-phase route to colloidal 1D nanostructures with controlled sizes, compositions, and properties. However, direct growth of 1D nanostructure arrays through SLS processes remains in its infancy. Herein, this study shows that SLS processes are also suitable for the growth of nanorod arrays on the substrate. As a proof of concept, seedless growth of silica nanorod arrays on a variety of hydrophilic substrates such as pristine and oxide-modified glass, metal sheets, Si wafers, and biaxially oriented polypropylene film are demonstrated. Also, the silica nanorod arrays can be used as a new platform for the fabrication of catalysts for photothermal CO₂ hydrogenation and the reduction of 4-nitrophenol reactions. This work offers some fundamental insight into the SLS growth process and opens a new avenue for the mild preparation of functional 1D nanostructure arrays for various applications.

Keywords: CO2 hydrogenation; catalysis; nanorod arrays; silica nanostructures; solution–liquid–solid growth.

Figure 1

Schematic illustration of the seedless growth of silica nanorod arrays on the substrate.

Figure 2

SEM images of a typical sample of SiO₂ nanorod arrays grown on the ITO glass slide viewed from different directions. The growth temperature was 60 °C and the growth time was 4 h.

Figure 3

SEM images of SiO₂ nanorod arrays grown on ITO glass substrates obtained at different growth times: a) 1, b) 2, and c) 4 h. d) The dependence of nanorod length and diameter on the growth time; SEM images of SiO₂ nanorod arrays grown on ITO glass substrates at different temperatures: e) 20, f) 40, and g) 60 °C. h) The dependence of nanorod length and diameter on the growth temperature.

Figure 4

SEM images of SiO₂ nanorods grown on different substrates: a) pristine glass, b) FTO glass, c) titanium sheets, and d) plasma‐treated Si wafers.

Figure 5

a) Schematic illustration of the sputtering different metals onto the surface of SiO₂ nanorod arrays. b–e) Element mapping of one rod from the Co@SiO₂‐array sample. f–g) Photothermal catalytic performance of Co@SiO₂‐array (in black), Co@SiO₂‐sphere (in red), and Co‐glass (in blue). h–k) Element mapping of one rod from the Au@SiO₂‐array sample. l) Time‐dependent UV−vis spectra of the reaction solution in the presence of Au@SiO₂‐array for 10‐min intervals. m) Plot of ln (C _t/C ₀) versus the duration of the reduction reaction. C _t and C ₀ are the concentrations of 4‐nitrophenol at time t and time 0, respectively.