Electrodeposition of Prussian-Blue Analogs (PBA) for advanced sensors

Prussian blue analogues (PBAs) have emerged as an exciting new class of ion insertion materials that can be used for low-cost batteries but also as sensors. PBAs have the general formula A_xM[Fe(CN)₆]_y which can reversibly store small cations like Na⁺, K⁺, Li⁺ and potentially even multivalent cations.

Good electrode design is essential for diverse applications, such as long-term battery storage and structural batteries for e.g. robots, but also for ion sensors. PBAs may offer advantages for several of these applications. Depending on the choice of the chemical content and the way to synthesize the films, the chemistry of PBAs can be tuned towards the application requirements. Beyond its use as a active cathode material in batteries, it also shows great promise for sensing-related applications, like ion detection and thermometry, respectively, thanks to its capability to insert multiple cations within it organo-metallic lattice and its exceptional thermogalvanic properties. Some of these novel applications are being explored in our research group.

PBAs are typically synthesized via a precipitation method. This results in powders with a large number of vacancies and interference from solvent molecules in the structure, leading to reduced capacity and poor stability. An alternative route is to​ electrodeposit PBAs, where their precipitation can be triggered electrochemically on the surface of the electrodes. This synthesis route has been demonstrated recently in our group and much is still to be discovered. For example, adhesion of the films to their substrate remains a challenge, especially for thicker or denser films. Other challenges include tuning the composition, charge capacity and stability of the films, as well as gaining understanding in the deposition mechanism and their activation.

In this thesis, you will explore the electrodeposition of PBA films, building further on existing know-how in our group. You will study their electrochemical behaviour and ensure their long-term functionality with regards to possible applications. We will work towards novel insights about this exciting new material and specifically for their application in thermogalvanic sensors.