From Solid Solution to Intermetallic Compounds: Oxygen Evolution Reaction Activity Trends among Nb–Ni Phases

High Resolution Image Download MS PowerPoint Slide The electrochemical behavior of Nb–Ni binary phases in terms of electrocatalytic activity and stability under oxygen evolution reaction (OER) conditions was investigated. The outcomes of electrochemical studies in an alkaline electrolyte, supported by extensive characterization of electrode materials before and after electrochemical experiments, were provided. OER activities using the intermetallic compounds Nb 7 Ni 6 and NbNi 3 as electrocatalyst precursors were compared with those obtained with the solid solution of Nb x Ni 1- x ( x = 0.09) and a reference Ni foil under the same conditions. While Nb 7 Ni 6 deactivates gradually during benchmarking stability test (chronopotentiometry at current density of 10 mA cm –2 for 2 h), NbNi 3 possesses remarkable OER activity and keeps it stable not only under mild conditions of benchmarking experiment but also during long-term operation at elevated current densities (50, 100, and 200 mA cm –2 ). To understand the difference in chemical behavior and the OER performance of Nb–Ni compounds, extensive characterization was supported by carrying out quantum chemical calculations, shedding light on the charge distribution and chemical bonding in the investigated compounds.