Enhanced visible light photoelectrochemical performance of β-Bi2O3-TiO2/ITO thin films prepared by aqueous sol-gel

Journal of Solid State Electrochemistry - Semiconductor heterojunction of β-Bi2O3-TiO2/ITO thin films was prepared by aqueous sol-gel and their photoelectrochemical and photoelectrocatalytic...     

Mixed oxide semiconductors based on bismuth for photoelectrochemical applications

The structural and photoelectrochemical properties of mixed oxide semiconductor films of Bi-Nb-M-O (M = Al, Fe, Ga, In) were studied in order to explore their use as photoanodes in photoelectrochemical cells. These films were prepared on AISI/SAE 304 stainless steel plates by sol–gel dip-coating. The films were characterized by scanning electron microscopy—energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), and their photoelectrochemical properties were studied by open circuit potential (OCP) measurements, linear sweep voltammetry (LSV), and cyclic voltammetry (CV). SEM micrographs show homogeneous and rough films with agglomerates on the surface. EDS analyses show that the films are composed of Bi, Nb, and M, and the agglomerates are mainly composed of Bi. XRD analyses show a predominant crystalline phase of bismuth(III) oxide (Bi₂O₃) and a secondary phase composed of Bi-M mixed oxides. It is noteworthy that there was no identified niobium-based crystalline phase. XPS results reveal that the films are composed by Bi(III), Nb(V), and M(III). CV results show that the electrochemical behavior is attributed only to the semiconductor films which indicate a good coating of the stainless steel support. OCP measurements show that all the films have n-type semiconductor properties and exhibited photoresponse to the visible light irradiation. LSV results show that the application of a potential higher than +0.1 V enhances the photocurrent which can be attributed to an improved charge carrier separation. The results indicate that these materials can be used in photoelectrochemical cells.     

A Bioinspired Peptide in TIR Protein as Recognition Molecule on Electrochemical Biosensors for the Detection of E. coli O157:H7 in an Aqueous Matrix

Currently, the detection of pathogens such as Escherichia coli through instrumental alternatives with fast response and excellent sensitivity and selectivity are being studied. Biosensors are systems consisting of nanomaterials and biomolecules that exhibit remarkable properties such as simplicity, portable, affordable, user‑friendly, and deliverable to end‑users. For this, in this work we report for the first time, to our knowledge, the bioinformatic design of a new peptide based on TIR protein, a receptor of Intimin membrane protein which is characteristic of E. coli. This peptide (named PEPTIR‑1.0) was used as recognition element in a biosensor based on AuNPs‑modified screen‑printed electrodes for the detection of E. coli. The morphological and electrochemical characteristics of the biosensor obtained were studied. Results show that the biosensor can detect the bacteria with limits of detection and quantification of 2 and 6 CFU/mL, respectively. Moreover, the selectivity of the system is statistically significant towards the detection of the pathogen in the presence of other microorganisms such as P. aeruginosa and S. aureus. This makes this new PEPTIR‑1.0 based biosensor can be used in the rapid, sensitive, and selective detection of E. coli in aqueous matrices.