Nickel hydroxides derived from nickel dithioxamide coordination polymer as potential electrocatalyst for oxygen reduction reaction in alkaline solutions

Title : Nickel hydroxides derived from nickel dithioxamide coordination polymer as potential electrocatalyst for oxygen reduction reaction in alkaline solutions

Abstract:

Oxygen reduction reaction (ORR) is a key reaction in the number of electrochemical technologies directed towards energy storage and conversion such as alkaline fuel cells and metal-air batteries. Development of these technologies is hampered by sluggish oxygen reduction. For this reason, various electrocatalysts are being developed for ORR in alkaline solutions. Pt-based electrocatalyst offer low overpotential but lack long-term durability. Thus, 3d transition-metals materials have been targeted due to their low cost and stability in alkaline media. Recently, their hydroxides have been indicated as a stable and active catalyst for electrochemical ORR.

In this presentation we will show that nickel hydroxides (Ni(OH)₂ /NiOOH) derived via an electrochemical oxidation of a nickel dithioxamide Ni(dto) chelate polymer in 1M KOH are promising candidates for ORR in alkaline solutions. In the experiment, synthesized Ni(dto) was mixed with acetylene black and deposited on a glassy carbon electrode after mixing with polyvinylidene fluoride used as a binder. The electrode was subject to potential cycling in the range of 0.5-1.55 V vs RHE. In the first potential sweep, Ni(dto) underwent oxidation to produce nickel hydroxides dispersed in a carbon matrix. The resultant nanocomposite was characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrocatalytic activity of the nanocomposite towards ORR was studied in O₂-saturated 1 M KOH using cyclic voltammetry (CV) and rotating disk electrode (RDE) linear sweep voltammetry (LSV) methods. The nanocomposite showed an enhanced ORR activity with the onset potential of 0.78 V and E1/2 = 0.72 V vs RHE in O₂-saturated 1 M KOH solutions. Investigation of the electrode after potential cycling reveals a presence of NiOOH. In this presentation we will discuss the reaction mechanism and compare the results to our previous report on Cu(dto)-derived nanocomposite.

Biography:

Ihsan Budi Rachman is a PhD student in Rzeznickas’ group at Shibaura Institute of Technology (SIT). He received his Master degree from King Fahd University of Petroleum and Minerals, Saudi Arabia in 2017 in the field of chemical sciences. His current subject is 3d transition metals coordination polymers as oxygen reduction electrocatalyst. His supervisor, Prof. Izabela Rzeznicka, received her PhD degree from Hokkaido University in the field of surface reaction dynamics in 2004. Her current research subjects include investigation of surface reactions of electrified interfaces and biointerfaces.