Intrinsic Control in Defects Density for Improved ZnO Nanorod-Based UV Sensor Performance

Hitherto, most research has primarily focused on improving the UV sensor efficiency via surface treatments and by stimulating the ZnO nanorod (ZNR) surface Schottky barriers. However, to the best of our knowledge, no study has yet probed the intrinsic crystal defect generation and its effects on UV sensor efficiency. In this study, we undertake this task by fabricating an intrinsic defect-prone hydrothermally grown ZNRs (S1), Ga-doped ZNRs (S2), and defect-free microwave-assisted grown ZNRs (S3). The defect states were recognized by studying X-ray diffraction and photoluminescence characteristics. The large number of crystal defects in S1 and S2 had two pronged disadvantages. (1) Most of the UV light was absorbed by the defect traps and the e–h pair generation was compromised. (2) Mobility was directly affected by the carrier–carrier scattering and phonon scattering processes. Hence, the overall UV sensor efficiency was compromised based on the defect-induced mobility-response model. Considering the facts, defect-free S3 exhibited the best UV sensor performance with the highest on/off ratio, the least impulse response time, the highest recombination time, and highest gain-induced responsivity to 368 nm UV light, which was desired of an efficient passive metal oxide-based UV sensor. Our results were compared with the recently published results.

A Novel Electroactive Imide Oligomer and Its Application in Anticorrosion Coating

A novel aniline tetramer (AT) capped electroactive imide oligomer (EIO) for metal corrosion protection was successfully synthesized in this study. The chemical structure of the EIO was characterized by liquid chromatography-mass spectrometry and Fourier-transform infrared spectroscopy. Furthermore, the redox behavior of EIO was identified using electrochemical cyclic voltammetry studies. An EIO coated on a cold-rolled steel (CRS) electrode was found to possess superior corrosion resistance to polyimide (PI) on a series of electrochemical corrosion measurements in 3.5 wt.% NaCl solution over an extended period (30 days). The mechanism for the advanced corrosion protection of the PI coating on the CRS electrode could be attributed to the redox catalytic capabilities of the AT units present in the EIO. These capabilities may induce the formation of passive metal oxide layers on the CRS electrode. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to analyze the surface condition of the CRS after the corrosion test. EIO- and PI-coated electrodes were identified by a series of electrochemical measurements, including corrosion potential (Ecorr), polarization resistance (Rp), and corrosion current (Icorr) measurements, along with electrochemical impedance spectroscopy (EIS).

Tribo-electrochemical behavior of a ferritic stainless steel under applied potentials

A tribo-electrochemical characterization of a ferritic stainless steel has been carried out under reciprocating sliding against a corundum alumina pin in 0.02 M H2SO4 medium at room temperature. Theaim of this study is to present a refinement of the usually employed method to determine the synergismeffect occurring in a tribo system where the sample is made of passive metal and the counter body made ofinert material. The effects of mechanical, corrosion and synergistical contributions to tribocorrosion at eachinvestigated potential are discriminated. So as to further study the synergy, it is divided into two parts,electrochemistry-accelerated wear (EAW) and wear-accelerated electrochemistry (WAE), respectively.Focus is first addressed on the mechanical wear reference determination under cathodic polarization. It has been shown that depending on the selected cathodic potential a hydrogen effect or even a dissolutioncontribution could result in EAW contribution of about 60% of the overall degradation. These effects are avoided when polarization is made at a potential where the double layer thickness is maximum and couldserve as lubricant agent under friction. The wear volume found under these conditions could therefore be used as mechanical wear reference. In the anodic domain, with the employed set-up, it is possible to set anidle time long enough for the film to reform between each sliding. Charges released during pin motions periods are thus related to depassivation process only and are converted into WAE wear volumes using the Faraday’s law. Wear volumes are quite constant over the investigated range in the passive plateau. They are more important than what is observed at lower potentials because of great EAW wear volumes.However, the proportions of wear contributions to the overall material degradation are changing. Even if the mechanical contribution is quite constant over the considered passive range around 23%, a transfer isoccurring from the EAW contribution to the WAE one as the anodic potential is increased.

Electroactive Epoxy-Titania Hybrid Anti-Corrosive Coatings Prepared by Small Basic Molecule-Catalyzed Sol-Gel Route

This article, the preparation and corrosion protection studies of a series of electroactive epoxy titanium dioxide (EET) hybrid materials containing conjugated segments of electroactive amino-capped aniline trimer (ACAT) and titanium dioxide (TiO2) nanoparticles of ~100 nm in diameter was first presented. It should be noted that EET at higher concentration of TiO2 was found to reveal better corrosion protection effect as compared to neat electroactive epoxy coating on cold-rolled steel (CRS) electrode based on electrochemical corrosion measurements in 3.5 wt% NaCl electrolyte. Effective enhancement of corrosion protection of EET coatings could be interpreted by electroactive epoxy as a densely physical barrier coating and the redox catalytic capabilities of ACAT units existed in EET may induce the formation of passive metal oxide layers on CRS electrode. Further the well-dispersed TiO2 nanoparticles in EET matrix could act as effective hinder to enhance the oxygen barrier property of EET.