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Indium tin oxide (ITO), as an electrode, has superiority over metal electrodes commonly used for electroanalysis due to its low cost, low electrochemical background response, wide working potential window, easy surface functionalization and commercial availability. However, researchers have often modified its surface with electron mediators/electrocatalysts to improve its electrocatalytic properties. The modification of the ITO surface with electron mediators/electrocatalysts is tedious, time consuming, and expensive and often suffers from reproducibility problems. As an alternative to this modification step, scientists have tried to develop different strategies to utilize ITO without modification by electron mediators/electrocatalysts. The suitability of bare ITO electrodes i) to obtain potential electrochemical responses from some electroactive species with high signal to noise (S/N) ratios and ii) to possibly improve the S/N ratio with additional signal amplifying systems make it a very lucrative tool for electrochemists. To promote its advancement, it is of great significance to summarize the recent advances and to highlight its excellence in electroanalysis. Thus, this review summarizes literature published up to 2019, focusing specifically on self-electrocatalytic properties of ITO toward suitable electroactive molecules and signal amplification strategies from bare/electroinactive-binder-modified ITO platforms and evaluating their performance in electrochemical sensing. In addition, the review outlines the scope for further research in this context.

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Herein, we have successfully constructed a solid-state Z-scheme photosystem with enhanced light absorption capacity by combining the optoelectrical properties of AgNPs with those of the MoS 2 /RGO/NiWO 4 (Ag-MRGON) heterostructure. The Ag-MRGON Zscheme system demonstrates improved photo-electrochemical (PEC) water-splitting performance in terms of applied bias photon-to-current conversion efficiency (ABPE), which is 0.52%, and 17.3-and 4.3-times better than those of pristine MoS 2 and MoS 2 /NiWO 4 photoanodes, respectively. The application of AgNPs as an optical property enhancer and RGO as an electron mediator improved the photocurrent density of Ag-MRGON to 3.5 mA/cm 2 and suppressed the charge recombination to attain the photostability of ∼2 h. Moreover, the photocurrent onset potential of the Ag-MRGON heterojunction (i.e., 0.61 V RHE ) is cathodically shifted compared to those of NiWO 4 (0.83 V RHE ), MoS 2 (0.80 V RHE ), and MoS 2 /NiWO 4 heterojunction (0.73 V RHE ). The improved PEC water-splitting performance in terms of ABPE, photocurrent density, and onset potential is attributed to the facilitated charge transfer through the RGO mediator, the plasmonic effect of AgNPs, and the proper energy band alignments with the thermodynamic potentials of hydrogen and oxygen evolution.

Our work was devoted to studying the effect of different concentrations of Mentha spicata aqueous extract on the green synthesis of silver nanoparticles (AgNPs) in order to obtain the most effective of these concentrations for bacteria inhibitory activity. Different concentrations of the aqueous M. spicata extract (0.25, 0.50, 0.75, and 1.00 mM) were used as biological solvent to synthesize AgNPs by means of the reduction method. The crystal structure and morphology of the NPs were characterized UV–vis spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The inhibition effect of AgNPs on Escherichia coli was studied to determine the minimum inhibitory concentration (MIC). The dark yellow color of the M. spicata extract aqueous solution indicates the successful synthesis of the AgNPs. UV spectra of the NPs show a gradual increase in absorption with increasing concentration of aqueous M. spicata extract solution from 0.25 to 1.00 mM, accompanied by a shift in the wavelength from 455 to 479 nm along with a change in the nanoparticle size from 31 to 9 nm. The tests also showed a high activity of the particles against bacteria (E. coli) ranging between 15.6 and 62.5 µg/ml. From the AgNPs, it was confirmed that aqueous M. spicata extract is an effective biosolvent for the synthesis of different sizes of AgNPs according to the solvent concentration. The AgNPs also proved effectual for the killing of bacteria.