Sustainable Process Technology (SPT) / Photocatalytic Synthesis (PCS)
Daily supervisor: Martijn Blom Available from: 01-09-2018
Within the SPT and PCS groups, we are working on safe (non-toxic, non-flammable, non-explosive) electricity storage, using the bicarbonate-formate redox system (1). Energy is stored via the electrochemical conversion of a concentrated potassium bicarbonate solution to potassium formate (1) in an electrolyzer. This conversion is reversible and the reverse reaction can be operated to generate electricity.
The electrolyzer works by passing a current through two electrodes. At the negative electrode (cathode), the synthesis of formate occurs via half-reaction 2. The formate synthesis can be catalyzed by a palladium electro-catalyst that is coated onto the cathode. The coating is performed using a catalyst ink, which is prepared from suspended catalyst particles, ion-exchange polymer (ionomer) and a solvent (which evaporates). The ingredients and preparation of the ink, application method and drying method all have an influence on the catalyst-ionomer-electrode interface (shown schematically in Figure 1). Good interface properties are imperative for proper electrolyzer operation.
We have developed an adequate method for coating titanium electrodes with Pd/C catalyst and anion exchange ionomer (Fumion). However, the electrodes can suffer from coating breakdown and electrode optimization is incomplete. The student is tasked with developing the optimal ink composition, yielding high electrode activity (current), selectivity, energy efficiency and stability. An electrolyzer setup is available for electrode testing. Moreover, SEM imaging is available to actually visualize the catalyst coating and see the effect of ink composition. Parameters to vary include, but are not limited to: Catalyst selection/synthesis; ionomer selection and, ink composition and application method.