Application of Visible Light Photocatalysis with Particle Lithography To Generate Polynitrophenylene Nanostructures

Abstract

Visible light photoredox catalysis was combined with immersion particle lithography to prepare polynitrophenylene organic films on Au(111) surfaces, forming a periodic arrangement of nanopores. Surfaces masked with mesospheres were immersed in solutions of p-nitrobenzenediazonium tetrafluoroborate and irradiated with blue LEDs in the presence of the photoredox catalyst Ru(bpy)3(PF6)2 to produce p-nitrophenyl radicals that graft onto gold substrates. Surface masks of silica mesospheres were used to protect small, discrete regions of the Au(111) surface from grafting. Nanopores were formed where the silica mesospheres touched the surface; the mask effectively protected nanoscopic local areas from the photocatalysis grafting reaction. Further reaction of the grafted arenes with aryl radicals resulted in polymerization to form polynitrophenylene structures with thicknesses that were dependent on both the initial concentration of diazonium salt and the duration of irradiation. Photoredox catalysis with visible light provides mild, user-friendly conditions for the reproducible generation of multilayers with thicknesses ranging from 2 to 100 nm. Images acquired with atomic force microscopy (AFM) disclose the film morphology and periodicity of the polymer nanostructures. The exposed sites of the nanopores provide a baseline to enable local measurements of film thickness with AFM. The resulting films of polynitrophenylene punctuated with nanopores provide a robust foundation for further chemical steps. Spatially selective binding of mercaptoundecanoic acid to exposed sites of Au(111) was demonstrated, producing a periodic arrangement of thiol-based nanopatterns within a matrix of polynitrophenylene.

Facile synthesis of Z-scheme graphitic-C3N4/Bi2MoO6 nanocomposite for enhanced visible photocatalytic properties

“…3c shows an asymmetrical feature indicating the co-existence of a number of distinguishable nitrogen environments; fitting with four results in binding energies of 398.86, 399.80, 401.36 and 404.05 eV. The two peaks at 399.80 and 401.36 eV can be assigned to tertiary nitrogen (N-(C) 3 ) and amino functional groups having a hydrogen atom (C-N-H) [43,44]. The peak at 398.86 eV is typically attributed to N atoms sp 2 -bonded to two carbon atoms (C N-C), thus confirming the presence of graphite-like sp 2 -bonded g-C 3 N 4 [45].…”

“…Over the past two decades, considerable public and scientific attention has been focused on semiconductor photocatalysts in environmental pollution remediation field because of the simple fabrication procedures, environmental friendliness, transparency, and excellent plasticity [1][2][3][4][5]. Due to its high chemical stability, nontoxicity, long-term stability and low cost, titanium dioxide (TiO 2 ) has been widely used in toxic pollutant degradation applications [6][7][8][9][10].…”

Remote Hydroxylation through Radical Translocation and Polar Crossover

“…It is also possible that ground‐state fac ‐[Ir(ppy) 3 ] serves as an initiator by transferring an electron to 1 , while SET from radical intermediates such as 3 to 1 is a propagation step in a chain reaction that accounts for product formation. The reduction of arenediazonium salts in the dark under conditions in which SET is even less favorable have been observed elsewhere, albeit at lower efficiency,15a–c while the irreversible formation of alkyl radicals has been reported in a related context 15d. Similarly, a ground‐state Ru polypyridyl catalyzes the oxidative esterification of aldehydes without irradiation 15e.…”

Patterning Surfaces through Photografting of Iodonium Salts

“…With deep UV light patterns below 20 nm are obtained. 25 Photosensitized grafting of diazonium salts has been demonstrated, [26][27][28] including local photografting. Millipipettes permit to pattern PVC surfaces with grafted nitrophenyl spots 26 while nanosphere lithography on gold (the mask consists of a layer of 500 nm silica spheres deposited on the surface) provides an array of triangular spots corresponding to the unmasked surface between the spheres.…”