Two functionalized graphene oxides, diazo pyridine functionalized graphene oxide and diamino pyridine functionalized graphene oxide, were synthesised and evaluated as corrosion inhibitors on mild steel in 1 M hydrochloric acid.

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The current study aims at the development of an electrochemical sensor based on a silver nanoparticlereduced graphene oxide-polyaniline (AgNPs-rGO-PANI) nanocomposite for the sensitive and selective detection of hydrogen peroxide (H 2 O 2 ). The nanocomposite was fabricated by simple in situ synthesis of PANI at the surface of rGO sheet which was followed by stirring with AEC biosynthesized AgNPs to form a nanocomposite. The AgNPs, GO, rGO, PANI, rGO-PANI, and AgNPs-rGO-PANI nanocomposite and their interaction were studied by UV-vis, FTIR, XRD, SEM, EDX and XPS analysis. AgNPs-rGO-PANI nanocomposite was loaded (0.5 mg cm À2 ) on a glassy carbon electrode (GCE) where the active surface area was maintained at 0.2 cm 2 for investigation of the electrochemical properties. It was found thatAgNPs-rGO-PANI-GCE had high sensitivity towards the reduction of H 2 O 2 than AgNPs-rGO which occurred at À0.4 V vs. SCE due to the presence of PANI (AgNPs have direct electronic interaction with N atom of the PANI backbone) which enhanced the rate of transfer of electron during the electrochemical reduction of H 2 O 2 . The calibration plots of H 2 O 2 electrochemical detection was established in the range of 0.01 mM to 1000 mM (R 2 ¼ 0.99) with a detection limit of 50 nM, the response time of about 5 s at a signal-to-noise ratio (S/N ¼ 3). The sensitivity was calculated as 14.7 mA mM À1 cm À2 which indicated a significant potential as a non-enzymatic H 2 O 2 sensor.

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The alkaline medium oxygen reduction reaction (ORR) activities of Ag–Cu bimetallic nanoparticles (BNPs), consisting of neighboring Ag and Cu domains, were studied and compared with those of pure Ag and Cu nanoparticles prepared by the same polyol route. Three variations of Ag–Cu BNPs viz. Ag–Cu (4:1), Ag–Cu (2:1), Ag–Cu (1:1) BNPs were considered. The electrocatalytic performances of these nanoparticles were investigated by using different techniques, such as cyclic voltammetry (CV) and linear sweep voltammograms (LSV). The Ag–Cu bimetallics demonstrated synergistic ORR electrocatalytic activity compared to pure Ag or Cu. Optimum values of these parameters were observed for Ag–Cu (4:1) BNPs. According to LSV, the reduction peak position is at lower applied potential and showed higher intensity for the Ag–Cu (4:1) as compared to Ag–Cu (2:1) and Ag–Cu (1:1) BNPs. Density Functional Theory (DFT) calculations show that charge transfer from Cu to Ag (in the bimetallic nanoparticles) results in their stronger oxygen interaction and water activation properties relative to that of pure Ag nanoparticles.

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