IrO₂/Ir Composite Nanoparticles (IrO₂@Ir) Supported on TiN_xO_y Coated TiN: Efficient and Robust Oxygen Evolution Reaction Catalyst for Water Electrolysis

Abstract

It is crucial but challenging to reduce the required noble-metal loading without compromising the catalytic performance of oxygen evolution reaction (OER) catalysts. This study presents a highly active OER catalyst composed of IrO 2 with Ir rich surface (IrO 2 @Ir) nanoparticles supported over nano TiN coated with TiO x N y (IrO 2 @Ir/TiN). The present approach demonstrates superior OER catalysts with high activity through small, uniformly dispersed IrO 2 @Ir nanoparticles, along with high durability owing to robust catalyst support and strong catalyst-support interaction. The synthesized IrO 2 @Ir/TiN with an Ir loading of 40 wt % exhibits a mass-normalized OER activity of 637 Ag Ir À 1 , which is 2.4 times that of the unsupported commercial benchmark IrO 2 OER electrocatalyst. The fine nanoparticles and high activity enable significant (~60 %) reduction in the Ir metal loading required to obtain equivalent OER performance. In addition, when evaluated through an accelerated stress test using potential cycling, the catalyst exhibits outstanding durability (79 % retention) compared to that of the commercial equivalent (66 % retention). The OER activity loss was attributed to the catalyst dissolution (30 % loss) and the catalyst particle growth (70 %), with no measurable loss due to the TiN support corrosion. The development of ultra-fine IrO 2 @Ir nanoparticles and robust ceramic catalyst support significantly improved the Ir utilization and open a new perspective for supported OER catalyst.

Multiple Bubble Removal Strategies to Promote Oxygen Evolution Reaction: Mechanistic Understandings from Orientation, Rotation, and Sonication Perspectives

“…All electrochemical measurements were carried out using a ZahnerIM6e potentiostat. The OER activity of different setups was studied as a similar method described in the previous literature of our group . For this purpose, the electrode was activated through potential cycling between 1.0 and 1.7 V for 50 cycles at a scan rate of 100 mV/s.…”

“…Then, the corresponding potential at 10 mA cm –2 in the J – V graph was deduced by the theoretical value for overpotential (1.23 V) and the remainder was reported as catalyst overpotential. Furthermore, the stability of the electrocatalyst activity of samples was tested using the same three-electrode setup as cyclic voltammetry and by means of accelerated stress test (AST) by following a two-step protocol as the previous studies: , 1-stress cycling between 1.0 and 1.7 V for a total of 2000 cycles at a scan rate of 100 mV/s to obtain a steady response for OER activity and 2-evaluation cycling in between 1.0 and 1.65 V (scan rate 10 mV/s) for 2 cycles where the observed current in the uppermost potential of the second cycle was considered as OER mass activity after specific cycles. The evaluation step was performed after 0, 20 cycles, then between 100 and 600 cycles with 100 cycles step, and finally every 200 cycles to the final 2000 cycles of the AST procedure.…”

“…The OER activity of different setups was studied as a similar method described in the previous literature of our group. 38 For this purpose, the electrode was activated through potential cycling between 1.0 and 1.7 V for 50 cycles at a scan rate of 100 mV/s. Then, the measurement of the OER activity of the electrode was tested in the potential range of 1.0−1.65 V for two cycles at a scan rate of 10 mV/s.…”

Strong Metal‐Support Interactions in ZrO2‐Supported IrOx Catalyst for Efficient Oxygen Evolution Reaction

“…The authors have cited additional references within the Supporting Information. [14,31,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]52,53,56,57,60,69,[92][93][94][95][96][97][98][99][131][132][133][134][135][136][137][138][139][140][141][142][143]…”

“…The authors have cited additional references within the Supporting Information [14,31,33–50,52,53,56,57,60,69,92–99,131–143] …”