Boosted Performance of Ir Species by Employing TiN as the Support toward Oxygen Evolution Reaction

Abstract

Reducing the noble-metal loading without sacrificing the catalytic performance of the oxygen evolution reaction (OER) catalysts is paramount yet highly challenging. Herein, IrO2@Ir/TiN electrocatalysts employing TiN as the support have been developed and shown high efficiency toward OER. TiN is found not only to disperse the IrO2@Ir nanoparticles effectively but also to exert the electronic modulation of Ir by downshifting its d-band center of 0.21 eV compared to pure IrO2. Excitingly, TiN remarkably enhances the catalytic performance of Ir, where the overpotential to achieve the current density of 10 mA cm–2 is only 265 mV for the IrO2@Ir/TiN (60 wt %) catalyst. As a result, 71.7 wt % of the Ir metal can be saved to compare with the commercial Ir-black counterpart. Moreover, TiN can inhibit the aggregation and oxidative dissolution of Ir species, thereby enhancing the operational stability. The combined advantages of TiN open a new solution to reduce the anodic catalyst cost through boosting the catalytic activity and stability.

Electrocatalysis for the Oxygen Evolution Reaction in Acidic Media: Progress and Challenges

“…For example, Ir nanoparticles can be well dispersed onto the TiN carrier. The IrO2@Ir/TiN catalyst prepared by Xing's group showed an enhanced catalytic performance [50]. The overpotential was only 265 mV at a current density of 10 mA•cm −2 .…”

“…Ir-based catalysts also suffer similar degradation issues [49]. During the long-term catalytic process, rutile oxide of IrO x will transition to other kinds of phases that are soluble in acid media [50]. Therefore, the harsh operating conditions must be taken into account when designing suitable catalysts.…”

“…The re-arranged electrons that have a significant impact on the catalytic performance will be confined in a space several atomic layers thick at the interface [74]. The magnitude and direction of the charge transfer are driven by differences in the Fermi level of the catalytic center and the support [50]. In addition, due to the special microenvironment at the interface, the interface sites will be in direct contact with the catalytic center, the carrier, and the reactants in order to promote the occurrence of synchronous reactions [37].…”

Electrocatalytic Oxygen Evolution Reaction in Acidic Conditions: Recent Progress and Perspectives

“…[142] More importantly, to further reduce the noble metal usage, a series of substrates, including carbon, graphene, metal nitrides (e. g., Fe 4 N, TiN), and antimony-doped tin oxide (ATO), have been widely used as support for Ru and/or Ir nanomaterials due to their high surface area, good electroconductivity, and excellent stability. [146][147][148][149][150] For instance, Tackett et al designed a unique core-shell structure with iridium/metal nitride morphology. Owing to the typical core-shell structure, the Ir mass activity in the iridium/metal nitride material exhibits 2.0 times higher than that of commercial IrO 2 .…”

Nanocatalyst Design for Long‐Term Operation of Proton/Anion Exchange Membrane Water Electrolysis

“…showed that IrO 2 @Ir on TiN (IrO 2 @Ir/TiN) featured stable OER performance in 0.50 m H 2 SO 4 . [ 95 ] When tested by CP, IrO 2 @Ir/TiN showed stable OER activity with only a 17.6 mV increase of overpotential after 6 h of operation. ICP‐optical emission spectroscopy (OES) showed the Ir dissolution of the IrO 2 @Ir/TiN with less than half of that of the unsupported IrO 2 @Ir, indicating the effective role of TiN to the preservation of Ir from dissolution (Figure 11e).…”