Synthesis of carbon dots (CDs) from natural resources not only enables green synthesis and production of environmentally friendly materials, but also provides a cost-effective probe as a fluorescence nanosensor. The proposed sensor introduces a unique one-pot hydrothermal CDs synthesis from alfalfa leaves, which is promising for sensing hydrochlorothiazide (HCTZ) via inner filter effect (IFE) and resonance Rayleigh scattering (RRS). The as-prepared CDs had wide emission spectra, excitation-dependent emission, high solubility, high stability, and visible fluorescence light with a quantum yield of up to 11%. The absorption of HCTZ overlapped with the excitation spectra of CDs. Therefore, CDs represented excellent quenching due to IFE when HCTZ was gradually added. Furthermore, this fluorescent sensor was successfully used to quantify HCTZ in the linear ranges (0.17-2.50 μg mL-1) with the limit of detection of 0.11 μg mL-1. The sensing system was simple as no surface functionalization was required for CDs, leading to less laborious steps and more cost-effective synthesis. The reaction time was short, i.e., less than 2 min, indicating a simple approach for rapid analysis of HCTZ. By optimizing conditions, successful measurements were carried out on pharmaceutical tablets.

Solar cells (Gratzel cells) have been highly regarded due to their extremely efficient and low-cost process of converting sun light into electricity. In this work screen printed electrodes were fabricated by spraying organic and organometallic dyes on glass and flexible aluminum foil. These solar cells were prepared based on three dyes, namely nickel Di thiocyanato bis(triphenyl phosphine), nickel Dimethylglyoxime and Nile blue, and the performance of these dye-sensitized solar cells (DSSC) has been experimentally evaluated. The solar cells were fabricated using thin TiO2 films; these films were characterized by FTIR. The dyes were characterized using UV-Vis and typical J-V and P-V curves of the cells. The best performance was obtained for the mixture of nickel Dithiocyanatobis (triphenyl phosphine) and Nile blue with an open circuit voltage (Voc) of 976 mV using an incident irradiation of 100 mW cm-2 at 25 C.

Um filme eletroativo fino, de pentacianonitrosilferrato de cobalto (CoPCNF), foi eletrodepositado em um eletrodo de carbono vítreo por voltametria cíclica. O eletrodo modificado exibe boa atividade eletrocatalítica frente à oxidação de tiossulfato. A oxidação eletrocatalítica de tiossulfato em eletrodo de carbono modificado com CoPCNF, como um eletrodo de trabalho, tem sido estudada usando-se voltametria cíclica, voltametria com eletrodo de disco rotatório (RDE) e cronoamperometria, em uma solução de 0,25 mol L-1 KNO3, como eletrólito de suporte. Um gráfico de Tafel, obtido dos voltamogramas, indicou como etapa determinante na velocidade da reação de oxidação do tiossulfato, o processo de transferência de carga de um elétron. A cinética da reação catalítica foi investigada e o valor médio da constante de velocidade (k) para a reação catalítica e o coeficiente de difusão (D) foram avaliados por diferentes aproximações para tiossulfato. Foram encontrados os valores de (5,61 ± 0,14) <FONT FACE=Symbol>´</FONT>10² (mol L-1)-1s-1 e (6,59 ± 0,70) <FONT FACE=Symbol>´</FONT>10-6 cm²s-1, respectivamente.

An electroactive thin film of Cobalt pentacyanonitrosylferrate (CoPCNF) was electrodeposited on a glassy carbon electrode by cyclic voltammetry. The modified electrode exhibits good electrocatalytic activity toward oxidation of thiosulfate. The electrocatalytic oxidation of thiosulfate at glassy carbon electrode modified with CoPCNF as a working electrode has been studied by using cyclic voltammetry, rotating disk electrode (RDE) voltammetry and chronoamperometry in a solution of 0.25 mol L-1 KNO3 as a supporting electrolyte. A Tafel plot, derived from voltammograms indicated a one-electron charge transfer process, at rate determining step in the catalytic oxidation of thiosulfate. The kinetics of catalytic reaction was investigated and the average value of the rate constant (k), for the catalytic reaction and the diffusion coefficient (D) were evaluated by different approaches for thiosulfate and found to be (5.61 ± 0.14) <FONT FACE=Symbol>´</FONT>10² (mol L-1)-1s-1 and (6.59 ± 0.70) <FONT FACE=Symbol>´</FONT>10-6 cm²s-1 respectively.