Oxide‐Supported IrNiO_x Core–Shell Particles as Efficient, Cost‐Effective, and Stable Catalysts for Electrochemical Water Splitting

Abstract

Active and highly stable oxide-supported IrNiO(x) core-shell catalysts for electrochemical water splitting are presented. IrNi(x)@IrO(x) nanoparticles supported on high-surface-area mesoporous antimony-doped tin oxide (IrNiO(x)/Meso-ATO) were synthesized from bimetallic IrNi(x) precursor alloys (PA-IrNi(x) /Meso-ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA-IrNi(x)/Meso-ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core-shell particles. The core-shell IrNiO(x)/Meso-ATO catalyst displayed high water-splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability.

Selective-leaching method to fabricate an Ir surface-enriched Ir-Ni oxide electrocatalyst for water oxidation

“…Finally, in order to explore the origin of the improvement in OER activity, the surface-specific OER activity was determined. Compared to pure Ir oxide, the surface-specific catalytic current density (current normalized by q, j spec ) on pyrolyzed-Ir 0.7 Ni 0.3 O x is increased by a factor of about 1.4, which exhibits the same trend as that in the recent work of Reier et al [40] In contrast, the leached-Ir 0.7 Ni 0.3 O x catalyst shows relatively lower surface specific activity maybe due to the phase segregation into a NiO and an Ir-rich nanophase [49]. A rough estimate value of Tafel slope for these three sample is~60 mV/decade in a relatively low potential range (1.48~1.56 V), which has been usually reported for OER on Ir-based electrodes prepared by thermal decomposition [50,51].…”

Nanosized IrOx–Ir Catalyst with Relevant Activity for Anodes of Proton Exchange Membrane Electrolysis Produced by a Cost‐Effective Procedure

“…[7,8] Forwater splitting in PEM electrolyzers,the choice of the oxygen evolution reaction (OER) catalyst employed at the anode has ap rofound impact on the cost, lifetime,a nd efficiency of the device.Iridium is commonly used as aOER catalyst, but is highly priced ($546 per troy ounce) [9] and one of the rarest elements in the earth crust, with an annual production and consumption value of only about 4t o9 tons. [10][11][12] Several approaches have been proposed to overcome the challenges associated with the precious metal OER catalyst such as reducing the particle size,thereby increasing the surface to mass ratio, [13] using electro-ceramic supports, [14,15] or enhancing the phase structure. [16] These characteristics can be modified through different approaches,while adirect modification during synthesis without post-treatment represents an attractive way to reduce production costs influencing the commercialization of future catalysts.…”

Nanosized IrOx–Ir Catalyst with Relevant Activity for Anodes of Proton Exchange Membrane Electrolysis Produced by a Cost‐Effective Procedure

“…[7,8] Forwater splitting in PEM electrolyzers,the choice of the oxygen evolution reaction (OER) catalyst employed at the anode has ap rofound impact on the cost, lifetime,a nd efficiency of the device.Iridium is commonly used as aOER catalyst, but is highly priced ($546 per troy ounce) [9] and one of the rarest elements in the earth crust, with an annual production and consumption value of only about 4t o9 tons. [10][11][12] Several approaches have been proposed to overcome the challenges associated with the precious metal OER catalyst such as reducing the particle size,thereby increasing the surface to mass ratio, [13] using electro-ceramic supports, [14,15] or enhancing the phase structure. [16] These characteristics can be modified through different approaches,while adirect modification during synthesis without post-treatment represents an attractive way to reduce production costs influencing the commercialization of future catalysts.…”