Nickel and Commercially Available Nickel‐Containing Alloys as Electrodes for the Electrochemical Oxygen Evolution

Abstract

AbstractWater electrolysis is a crucial technology for independency on fossil fuels. However, water splitting is limited by the sluggish kinetics of oxygen evolution reaction (OER). While many studies report highly active, non‐precious metal‐based electrocatalysts for alkaline OER, applicability under industrial conditions is often omitted. Such conditions require catalysts being applied on nickel or nickel‐containing alloys in elevated electrolyte concentrations. In contrast to the rather inert substrates often used in scientific studies, such industrially applied substrates exhibit significant OER activity themselves and show dynamic behaviour. Therefore, it is crucial to understand the OER behaviour of such substrates. Here, nickel and seven commercially available nickel‐containing alloys are investigated as anodes in alkaline OER and their elemental compositions correlated to their corresponding activities. Repeated potential cycling across the Ni(II)/Ni(III)‐redox couple is established as activity‐enhancing procedure. Overall, the nickel‐base alloy Hastelloy® X exhibits the highest activity due to its Fe‐, Cr‐, Mo‐ and Co‐content. Though, the activity gain differs significantly for the various materials. Comparing Ni and Hastelloy® X as least and most active materials, the positive impact of activation on both activity and stability becomes evident. While untreated Ni suffers from poor OER stability, the activity‐enhancing procedure also significantly increases electrode stability in 24 h chronopotentiometry.