Electrografting of 4-Nitrobenzenediazonium Salts on Al-7075 Alloy Surfaces—The Role of Intermetallic Particles

Abstract

In this work, the electrografting of Al-7075 aluminium alloy substrates with 4-nitrobenzenediazonium salt (4-NBD) films was studied on a complex aluminium alloy surface. Prior to the electrografting reaction, the substrates were submitted to different surface treatments to modify the native aluminium oxide layer and unveil intermetallic particles (IMPs). The formation of the 4-NBD films could be correlated with the passive film state and the distribution of IMPs. The corresponding electrografting reaction was performed by cyclic voltammetry which allowed the simultaneous analysis of the redox reaction by a number of complementary surface-analytical techniques. Spatially resolved thin film analysis was performed by means of SEM-EDX, AFM, PM-IRRAS, Raman spectroscopy, XPS, and SKPFM. The collected data show that the 4-NBD film is preferentially formed either on the Al oxide layer or the IMP surface depending on the applied potential range. Potentials between −0.1 and −1.0 VAg/AgCl mostly generated nitrophenylene films on the oxide covered aluminium, while grafting between −0.1 and −0.4 VAg/AgCl favours the growth of these films on IMPs.

Nickel-Induced Reduced Graphene Oxide Nanoribbon Formation on Highly Ordered Pyrolytic Graphite for Electronic and Magnetic Applications

“…The scanning Kelvin probe force microscopy (SKPFM) analysis was performed to determine the contact potential differences on the A much more detailed explanation on the nobility, polarity, referencing, and other precautions when working with SKPFM is provided in the seminal contributions reported by Su et al 26 The Raman spectra of the samples were obtained by an InVia Renishaw confocal Raman microprobe system (Renishaw RE 04plc, Gloucestershire, UK) equipped with a Leica DM 2500 M confocal microscope and an λ = 532 nm laser.…”

“…To this end, ScanAsyst-Air-HR (130–160 kHz, 0.4–0.6 N·m –1 , and nominal radius of 2 nm) tips, purchased from Bruker, were used. In order to minimize tip convolution effects affecting the NPs width, data obtained from AFM image profiling have been corrected according to Canet-Ferrer et al 25 For the characterization of both the shape and size of the nanoparticles and nanoribbons, NPs and NRs, respectively, 26 freshly cleaved HOPG substrates were incubated for t = 1 h in a 20% (w/w) Ni-rGO-containing solution by drop casting a 100 μL droplet. After that, the modified surfaces were thoroughly rinsed with ultrapure water and dried under a N 2 stream.…”

“…Intermediate positive potential figures were recorded for the Si domains. A much more detailed explanation on the nobility, polarity, referencing, and other precautions when working with SKPFM is provided in the seminal contributions reported by Su et al 26 …”