Drochss P. Valencia

High Electrocatalytic Response of a Mechanically Enhanced NbC Nanocomposite Electrode Toward Hydrogen Evolution Reaction

Resistant and efficient electrocatalysts for hydrogen evolution reaction (HER) are desired to replace scarce and commercially expensive platinum electrodes. Thin-film electrodes of metal carbides are a promising alternative due to their reduced price and similar catalytic properties. However, most of the studied structures neglect long-lasting chemical and structural stability, focusing only on electrochemical efficiency. Herein we report on a new approach to easily deposit and control the micro/nanostructure of thin-film electrodes based on niobium carbide (NbC) and their electrocatalytic response. We will show that, by improving the mechanical properties of the NbC electrodes, microstructure and mechanical resilience can be obtained while maintaining high electrocatalytic response. We also address the influence of other parameters such as conductivity and chemical composition on the overall performance of the thin-film electrodes. Finally, we show that nanocomposite NbC electrodes are promising candidates toward HER and, furthermore, that the methodology presented here is suitable to produce other transition-metal carbides with improved catalytic and mechanical properties.

Chapter 3 - Electrochemical Monitoring of the Pharmacological Activity of Natural Products

Abstract Electrochemical techniques have largely been applied to characterize the redox reactivity of natural and synthetic compounds and to determine natural and synthetic compounds in solution. A series of new applications of electrochemistry that has emerged in the last few decades and aims to obtain information on the pharmacological activity of natural products is reviewed. Such applications involve the following: (1) electrochemical testing of specific pharmacological activity via electrochemical screening; (2) in situ evaluation of drug–substrate interactions, including the study of pharmacologically active natural products and their metabolites; (3) electrochemical mimicry of selected biological redox processes to observe correlations between molecular structure, redox properties, and pharmacological activity based on (a) thermochemical properties and/or (b) kinetic properties; (4) promoting electrochemical activation of the pharmacological activity; and (5) in situ generation of redox-active species (typically, reactive oxygen species) involved in the mechanisms of the pharmacological activity of natural products and the study of the involvement of these natural products in pharmacological/toxicological processes.