Bryan Byles, Drexel University
Tunnel Structured Manganese Oxides as Electrode Materials for Hybrid Capacitive Deionization
Written by Armin VahidMohammadi
Bryan Byles from Drexel University explained the research group’s work on capacitive deionization using tunnels structured manganese oxides. In their research, at first and through performing XRD analysis, uniform tunneled structure was assumed; however, when they performed TEM studies, it was observed that it is not always the case for different manganese oxides. In this research, activated carbon was used as counter electrode and manganese oxide with different structures was used as the working electrode for the purpose of capacitive deionization. To confirm the change in the ion concentration, they had used a conductivity probe to measure the conductivity of the solutions before and after test, which from that, the concentration of ions can be found out. Byles mentions that the ion-removal step was done for 15 min at +1.2 V, and the ion-release step was carried out for 15 min at -1.2 V. It was shown that the ion-removal capacitance they were achieving at the beginning was further maintained through several cycles. Among different structures studied, alpha manganese oxide had shown the highest capacitive in potassium chloride (KCl) solution. From their different electrode structure and various experiments, it was concluded that electrodes with smaller tunnels in their structure have preference for adsorption of smaller ions and larger ions have preference for larger ions. Byles concluded his talk by pointing out that through investigating three different types of manganese oxide, the researchers were able to find out the size relation of tunnels in the structure of their electrode and ions. It can be easily concluded that the crystal structure engineering is a key parameter to improve materials performance for capacitive deionization.