Electrodeposited Ni-Based Catalysts for the Oxygen Evolution Reaction

Abstract

Alkaline water electrolysis is one of the most mature technologies for producing green hydrogen. However, there still are possibilities to enhance this process by using better electrocatalysts for the kinetically limited oxygen evolution reaction (OER). While there are several existing methods for catalyst synthesis, such as spray coating, coprecipitation and hydrothermal synthesis, they face challenges of either versatility or scalability. [1,2] In this regard, electrodeposition is a promising catalyst synthesis method, due to its excellent process control and ease of scalability. In this work, electrodeposition is used to prepare nickel-based catalysts as a benchmark system. These catalysts are deposited on expanded Ni-mesh supports. Initially, the deposition parameters are optimized to obtain uniform Ni deposits, which provide reproducible activity measurements. Herein, we observe that the deposited Ni catalysts exhibit better OER activities than the Ni mesh support, most likely due to the evolution of a pyramidal morphology with an increased surface area (Fig. 1). The optimized deposition parameters are further used to deposit different Ni-based alloys such as Ni-Fe and Ni-Co, by adding the respective ionized metal species to the Ni electrolyte. The microstructure and composition of these catalysts is analyzed using material characterization techniques like scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Finally, the OER activity and long-term stability of the deposited catalysts is evaluated in an in-house developed electrochemical beaker cell at elevated concentration, temperature, and current densities (30 wt.% KOH, 80 °C, up to 1 A/cm 2 ). The results obtained for the different catalysts are compared to understand the correlation of the catalyst structure and composition with their electrochemical OER performance under industrial conditions. Bibliography [1] Lu Xunyu et al.; Nature Communications; DOI: 10.1038/ncomms7616 [2] Zuraya Angeles-Olvera et al.; Energies ; DOI: 10.3390/en15051609 Figure 1