Efficient and Stable Evolution of Oxygen Using Pulse-Electrodeposited Ir/Ni Oxide Catalyst in Fe-Spiked KOH Electrolyte

Abstract

Metal oxides have been extensively explored as catalysts for the electrochemical oxygen evolution reaction (OER). Here, we present an excellent OER catalytic system consisting of pulse-electrodeposited Ir/Ni oxides in Fe(3+)-spiked 1 M KOH. In pure 1 M KOH electrolyte, the optimized catalyst, which had an Ir:Ni atom ratio of 1:1.49, could catalyze 10 mA/cm(2) of O2 production at a small overpotential (η) of 264 mV. Remarkably, we found that its OER performance could be significantly improved by adding 0.3 mM Fe(3+) into the electrolyte. At an η of just 343 ± 3 mV, a huge current of 500 mA/cm(2) was achieved. Furthermore, this catalytic system exhibited a small Tafel slope of 31 mV/dec and a large iridium mass-normalized current of 1260 mA/mgIr at η = 280 mV. We also discovered that the durability of the Ir/Ni oxide catalyst during OER (at 10 mA/cm(2) with η < 280 mV) could be maintained for more than 4.5 days by simply spiking Fe(3+), Ir(3+), and Ni(2+) into the KOH electrolyte. The figures-of-merit in this work, in terms of both activity and stability, compare favorably against values from several state-of-the-art catalysts. Hypotheses for the outstanding performance of the Ir/Ni catalyst are proposed and discussed.

Ir-Ni Bimetallic OER Catalysts Prepared by Controlled Ni Electrodeposition on Irpoly and Ir(111)

“…The superior OER performance of the Ni/Ir poly OL catalyst can be deduced to surface enrichment of Ir atoms promoting positive synergies between Ir and Ni atoms. The increase in activity with Ir-Ni binary systems has been observed in various studies in alkaline and acidic electrolytes [23,[28][29][30]. The higher activity of Ni/Ir poly OL in acidic electrolyte may be assigned to an increase of surface OH groups initiated by leaching off Ni adatoms from the surface [23].…”

“…In addition, during DEMS experiments, the purge N 2 was kept over the non-electrolyte contact areas of the electrode to ensure that the electrochemistry is running in an oxygen-free environment. DEMS measurements were monitorized with control product formation species with m/z values of 2,16,18,28,30,36,32,34,44 during the CV scan. The previously mentioned catalyst-specific calibration factor K j * was applied for quantification of the faradaic efficiency (FE)…”

Revealing the Impact of Electrolyte Composition for Co-Based Water Oxidation Catalysts by the Study of Reaction Kinetics Parameters

“…First, we should recall that the electrocatalytic activity of such amorphous catalysts is greatly affected by the presence of Fe-impurities in the alkaline electrolytes, 12,20,21,23,[49][50][51][52][53] and that the origin for such effects is still under intensive debate. For Fe-free electrolytes and films, the OER activity for CoOOH is found to be dependent on the concentration of KOH (Figure 4a).…”

Morphology-oxygen evolution activity relationship of iridium(iv) oxide nanomaterials

“…This electrochemical reaction is governed by electrosorption of OH À and the formation of a series of metal-oxygen intermediates such as M Ir -OO, M Ir -OH, M Ir -OOH, etc. 62,63 The following reactions are representations of metal cations on the active surface (S) interacting with a water molecule leading to the evolution of oxygen molecules. 64,65 M Ir + OH À -M Ir À OH + e À According to Viruthasalam et al, metal cations can be those oxidized and/or reduced during an electrochemical reaction over a modified electrode.…”