Metallic nanoparticles remain the focus of diverse studies across various fields due to their exceptional properties and applications in biology, sensing, energy, and (electro)catalysis. Typical syntheses of metallic nanoparticles are solution-based and require the use of stabilizing agents. Although these surface agents prevent agglomeration, they also hinder access to active sites on the nanoparticle surface. A promising alternative is mechanochemical synthesis, offering a solvent and surfactant-free approach, which yields uniform nanoparticles with clean surfaces. Here, we employ ball milling as a mechanochemical method to prepare metallic bismuth nanoparticles in a single step, using BiVO4 semiconductor both as a bismuth source and a support. Our results demonstrate that, in addition to the formation of nanoparticles by the partial reduction of BiVO4, there is an increase in charge carriers in the semiconductor structure as probed by electrochemical experiments. The final properties of Bi@BiVO4 material make it a relevant candidate for (electro)catalysis. biology sensing energy electrocatalysis. electrocatalysis electro catalysis. catalysis (electro)catalysis solutionbased solution based agglomeration synthesis surfactantfree surfactant free approach surfaces Here step BiVO support that experiments BiBiVO4 BiBiVO Bi Bi@BiVO

ABSTRACT Proteins have been the subject of electrochemical studies. It is possible to apply electrochemical techniques to obtain information about their structure due to the presence of five electroactive amino acids that can be oriented to the outside of the peptidic chain. These amino acids are L-Tryptophan (L-Trp), L-Tyrosine (L-Tyr), L-Histidine (L-His), L-Methionine (L-Met) and L-Cysteine (L-Cys); their electrochemical behavior being subject of extensive research, but it is still controversial. No spectroscopic investigations have been reported on L-Trp, and due to the short life time of the intermediates, ex situ techniques cannot be employed, leading to a never-ending discussion about possible intermediates. In the L-Tyr and L-His cases, spectroelectrochemical studies were performed and different intermediates were observed, suggesting that some intermediates may be observed under specific conditions, as proposed for L-Cys. This amino acid is the most interesting among the electroactive ones because of the presence of a thiol moiety at its side chain, leading to a wide range of oxidation states. It can adsorb onto surfaces of different crystallographic orientation in stereoselective conformation, modifying the surface for different applications.as a surface engineering tool since it plays the role of as an anchor for the growing of nanocrystals inside proteic templates.

Electrodes modified with poly(5-amino-1-naphthol)/Prussian blue (poly(5-NH2-1-NAP)/PB) hybrid films are able to electrochemically reduce H2O2 in medium containing an excess of Na+ cations. This is an important advantage for biosensing applications over electrodes in which only conventionally (electro) deposited Prussian blue is present. Consequently, the aim of this work was to examine the application of templates of ordered arrays of colloidal poly(styrene) spheres (800, 450 and 100 nm in diameter) to produce inverse opal structures of poly(5-NH2-1-NAP)/PB hybrid platforms, in an effort to study the influence of the increase in surface area/volume ratio and higher exposition of the mediator active sites on material performance during H2O2 determination employing the different sized porous structures. Moreover, since the accentuated hydrophilic character of poly(5-NH2-1-NAP)/PB also allows H2O2 electrochemical reduction in inner active sites, issues concerning the amount of mediator electrodeposited on the electrode were also reflected in the observed results.