ELECTROCHEMICAL CHARACTERIZATION OF ELECTRODE DEVICES: TOWARDS ENHANCED STABILITY IN ENERGY STORAGE AND PHOTOELECTROCHEMICAL CATALYSIS APPLICATIONS

To avoid further escalation of the climate crisis, current alternative energy technologies require immediate improvements to curb our reliance on fossil fuels. Renewable energy generation through solar panels and wind-turbines have undergone drastic improvements through the past decade, but due to their intermittence, cannot be the sole generators of electricity towards the power grid. Energy storage technologies, such as electrochemical batteries and photoelectrochemical hybrid electrodes are attractive alternatives to store power during periods of intermittence. Electrochemical battery technologies using lithium-ion batteries are the current state-of-the-art technologies to store electrical energy; however, due to safety and scarcity concerns, a stable and abundant alternative is needed. Zinc anode materials coupled with heterogenous air-cathodes have seen a resurgence, as the devices can match the performance of lithium-ion materials under milder conditions. Limiting the usage of zinc anode materials is the formation of dendrite that can pierce separators and cause device short-circuits. Zinc dendrite favors select nucleation areas which progressively grow over the course of device usage and eventually physically reach the cathode material causing critical failures. This work focuses on developing methodologies to curb zinc dendrite in alkaline conditions, specifically using ion additives and graphene oxide coatings to control the uninhibited nucleation. Stability of the zinc device is monitored by galvanostatic techniques and post mortem scanning electron microscopy (SEM) is used to investigate the integrity of the separator after charge cycling.Photoelectrochemical hybrid electrodes couple the vast knowledge of small-molecule-activation catalysis with the robust versatility of material electrodes. The activation of feedstock chemicals, through H2O oxidation, N2 reduction, and CO2 reduction, have long been studied in conjugation with artificial photosynthesis. Despite the thermodynamic and kinetically difficult process of small-molecule-activation towards fuel forming reactions, light has been considered an external driving force that can facilitate this catalysis. Driving electrochemistry with light to storing the energy in a chemical bond through a coupled electrocatalyst is one strategy that has seen several iterations of progress over the years. One strategy in particular, by coupling molecular catalysts with an electrode photosensitizer can unite the catalyst with a material that can harnesses light. Silicon is an attractive semiconductor electrode, with a 1.2 eV bandgap, making it compatible to drive electrochemistry with visible light as a photosensitizer. Additionally, many strategies have successfully protected silicon from undesired oxidative side reactions, further improving electrode durability. In this work, a Grignard strategy was developed to manufacture silicon hybrid electrodes that can support CO2 reduction catalysts. By grafting pyrene aromatic functionalities onto silicon, catalysts with aromatic appendages can anchor onto the electrode surface without an external chemical reaction. Coupling the Grignard process with a second methyl Grignard passivation step, allows for the formation of a mixed monolayer with improved resilience towards silicon oxidation sparked by water and oxygen. Upon anchoring a ruthenium CO2 reduction catalyst, several iterations of characterization are performed to validate anchoring, and electrochemical analysis coupled with gas chromatography is used to quantify CO2 reduction products.