Assisted water electrolysis

Abstract

Due to the growing climate changes, a shift in power sources is urgently needed. For that, efficient and renewable sources such as photovoltaics and wind power are interesting, but limited, since wind and sunlight present an ununiform territorial and seasonal distribution. A well-discussed strategy for the application of these sources is the storage of the excess energy produced during abundant times by the synthesis of chemical molecules, the so-called solar fuels. Between them, the hydrogen is highlighted, due to its high energy density and the possibility of production by electrochemical methods, such as water electrolysis. One of the issues for this is the high overpotential needed for this process, due to the oxygen evolution reaction (OER). That is why investigations on assisted water electrolysis are desirable. An alternative considered in this proposal is to assist the OER by localized surface plasmon resonance, in which the electric cloud of an Au nanoparticle is in resonance with the incident light, with a coherent wavelength, generating excited charge carriers that can decrease the voltage needed for the OER. Besides, other oxidation reactions such as ethanol and SO2 will be investigated in presence of plasmon resonance, decreasing the H2 generation voltage by radiation, as well as by changing the oxidation reaction. Another option for the oxidative reaction is the lignin electrocatalytic reforming, a process that generates high-value chemicals and fuels from biomass. These studies are going to be performed in conventional three-electrode cells, and under application conditions, using gas diffusion electrodes as working electrodes. Scanning electrochemical microscopy will detail the systems and allow the study of local properties in the presence and absence of light. Additionally, impedance techniques, such as multi-frequency Mott-Schottky, are going to be used to investigate the semiconductor oxides' properties as catalysts in alkaline media. (AU)