Ir/TiON_x/C high-performance oxygen evolution reaction nanocomposite electrocatalysts in acidic media: synthesis, characterization and electrochemical benchmarking protocol

Abstract

More efficient utilization of iridium is of immense importance for the future development of proton exchange membrane electrolyzers. In this study, we introduce a new facile and scalable synthesis of an Ir-based high-performance oxygen evolution reaction (OER) electrocatalytic nanocomposite. The composite consists of Ir nanoparticles with an average size of 3-4 nm, which are effectively anchored on a titanium oxynitride support (TiON x ), which is distributed across high-surface-area Ketjen Black carbon (Ir/TiON x /C). We provide complete structural, morphological and compositional characterization (x-ray diffraction, scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy) and propose a proper benchmark protocol to measure true electrochemical performance. Compared to the state-of-the-art Ir Black electrocatalyst, Ir/TiON x /C exhibits approximately three times higher OER performance.

Effect of the Morphology of the High-Surface-Area Support on the Performance of the Oxygen-Evolution Reaction for Iridium Nanoparticles

“…Thus, other backing electrodes, such as Au or Pt, should be employed for longer degradation tests in the future. 30 Here, a preliminary degradation test was performed on the catalyst by applying a constant current of 1 mA mg Ir –1 for 2 h. Electrochemical stability was investigated for the case of the three anodically grown catalysts. Our results show that the most stable catalyst is TiON x -3h-Ir, which retained 74.3% of the initial activity after 2 h ( Figure 8 ).…”

“…The final step of the OER catalyst’s preparation, i.e., the deposition of Ir in the form of finely dispersed, ultrasmall nanoparticles, was already demonstrated by our group. 30 − 32 In this investigation, we developed a new, anodic, oxidation-based synthesis process for the cost-effective fabrication of high-performance OER TiON x -Ir nanopowder electrocatalysts. The influence of the anodization time on the catalyst’s support morphology, structure, and composition was studied in detail using various state-of-the-art characterization methods, such as X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS).…”

Enhancing Iridium Nanoparticles’ Oxygen Evolution Reaction Activity and Stability by Adjusting the Coverage of Titanium Oxynitride Flakes on Reduced Graphene Oxide Nanoribbons’ Support

“…[58][59][60] Titanium oxynitride (TiON x ) presents suitable characteristics (electrical conductivity is comparable to high surface area carbons, good stability) to be considered as a support for OER catalysts. [58][59][60] However, materials based on titanium oxides usually have a low surface area, which makes it difficult to achieve a good dispersion of Ir nanoparticles. [61] This-in addition to lower Ir utilization-leads to having to deposit thick layers of the catalyst in real devices, which then, in most cases, causes mass transport issues.…”

Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

“…22 On the other hand, conductive titanium oxynitride is also a very promising candidate for electrocatalytic applications; 23,24 however, it is rarely employed for OER. Besides our recent studies, 11,25 there have been no other reports dealing with Ti oxynitrides in conjunction with Ir.…”