Nanostructured transition-metal phthalocyanine complexes for catalytic oxygen reduction reaction

Oxygen reduction reaction (ORR) plays a key role in the field of fuel cells. Efficient electrocatalysts for the ORR are important for fuel cells commercialization. Pt and its alloys are main active materials for ORR. However, their high cost and susceptibility to time-dependent drift hinders their applicability. Satisfactory catalytic activity of nanostructured transition metal phthalocyanine complexes (MPc) in ORR through the occurrence of molecular catalysis on the surface of MPc indicates their potential as a replacement material for precious-metal catalysts. Problems of MPc are analyzed on the basis of chemical structure and microstructure characteristics used in oxygen reduction catalysis, and the strategy for controlling the structure of MPc is proposed to improve the catalytic performance of ORR in this review.

Carbon Paste Modified Electrode as Powerful Sensor Approach Determination of Food Contaminants, Drug Ingredients, and Environmental Pollutants: A Review

Background:

Application of electrochemical sensors for analysis of food, biological and water polluting compounds helps to speed up their analysis in the real samples. Electrochemical sensors with low cost, fast response and portable ability are a better choice compared to traditional methods for analysis of electro-active compounds such as HPLC. Therefore, in recent years, many analytical scientists have suggested this type of analytical method for analysis of food, biological compounds and water pollutants.

Objective:

Due to low cost, easy modification and low non-faradic current, the carbon paste electrode is a suitable choice as a working electrode in the electrochemical and especially voltammetric analysis. On the other hand, modification of carbon paste electrode can improve the quality of the sensor for the analysis of electroactive compounds at nanomolar level.

Chemical analysis in saliva and the search for salivary biomarkers – a tutorial review

A review of the uses of saliva biomarkers, detection methods and requirements for new biomarkers.

Cobalt phthalocyanine modified electrodes utilised in electroanalysis: nano-structured modified electrodes vs. bulk modified screen-printed electrodes

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes l-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards l-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

Nanostructured metallophthalocyanine complexes: synthesis and electrocatalysis

In this review, we have attempted to summarize the synthesis and catalytic applications of the nanophthalocyanine complexes. In cases where possible, we have compared the catalytic activity of the nanophthalocyanines to the bulk material. Catalytic detection of dopamine, epinephrine, glucose and some pollutants using nanostructured metallophthalocyanine have been covered.

Electrochemical behavior of some purine derivatives on carbon based electrodes

The electrochemical behaviour of three purine derivatives was investigated by cyclic voltammetry on different electrode materials: glassy carbon in native form and electrochemically activated, carbon paste electrode unmodified or modified with 1, 4-benzoquinone. The preliminary study obtained on solid electrodes was extended to graphite based planar screen-printed electrodes, unmodified and modified with multi-wall carbon nanotubes, or cobalt phthalocyanine.

The influence of some experimental parameters (pH, scan rate, concentration and electrolytic medium) on the electrochemical behaviour of these alkaloids was also examined.

The electrochemical oxidation of purine derivatives is an irreversible and diffusion controlled process, proved by the linear dependence between the peak potentials and the logarithm of scan rates and between the anodic peak current and the square root of scan rate.

Studies on CuTAPc-nanotube-modified electrodes as chemical sensors for NO

Poly-copper tetraaminophthalocyanine (CuTAPc) nanotubes were successfully fabricated on porous alumina templates by electropolymerization. Their high surface area and simple preparation protocol made them potential candidates as the modification layer of electrodes for sensor application. High sensitivities and improved linear ranges were obtained through different measurements such as differential pulse voltammetry (DPV), differential potential amperometric (DPA) and electrochemical impedance spectroscopy (EIS). Detection limits as low as 10 nM were demonstrated in common voltammetric analysis with ultra-high response current in the microA range.

Preconcentration and Determination of Mercury(II) at a Chemically Modified Electrode Containing 3-(2-Thioimidazolyl)propyl Silica Gel

A mercury-sensitive chemically modified graphite paste electrode was constructed by incorporating modified silica gel into a conventional graphite paste electrode. The functional group attached to the (3-chloropropyl) silica gel surface was 2-mercaptoimidazole, giving a new product denoted by 3-(2-thioimidazolyl)propyl silica gel, which is able to complex mercury ions. Mercury was chemically adsorbed on the modified graphite paste electrode containing 3-(2-thioimidazolyl)propyl silica (TIPSG GPE) by immersion in a Hg(II) solution, and the resultant surface was characterized by cyclic and differential pulse anodic stripping voltammetry. One cathodic peak at 0.1 V and other anodic peak at 0.34 V were observed on scanning the potential from -0.1 to 0.8 V (0.01 M KNO3; v = 2.0 mV s(-1) vs. Ag/AgCl). The anodic peak at 0.34 V show an excellent sensitivity for Hg(II) ions in the presence of several foreign ions. A calibration graph covering the concentration range from 0.02 to 2 mg L(-1) was obtained. The detection limit was estimated to be 5 microg L(-1). The precision for six determinations of 0.05 and 0.26 mg L(-1) Hg(II) was 3.0 and 2.5% (relative standard deviation), respectively. The method can be used to determine the concentration of mercury(II) in natural waters contaminated by this metal.