Ir-Pd nanoalloys with enhanced surface-microstructure-sensitive catalytic activity for oxygen evolution reaction in acidic and alkaline media

Abstract

Ir-based electrocatalysts have been systematically studied for a variety of applications, among which the electrocatalysis for oxygen evolution reaction (OER) is one of the most prominent. The investigation on surface-microstructure-sensitive catalytic activity in different pH media is of great significance for developing efficient electrocatalysts and corresponding mechanism research. Herein, shape-tunable IrPd alloy nanocrystals, including nano-hollow-spheres (NHSs), nanowires (NWs), and nanotetrahedrons (NTs), are synthesized via a facile one-pot solvothermal method. Electrochemical studies show that the OER activity of the Ir-Pd alloy nanocatalysts exhibits surface-microstructure-sensitive enhancement in acidic and alkaline media. Ir-Pd NWs and NTs show more than five times higher mass activity than commercial Ir/C catalyst at an overpotential of 0.25 V in acidic and alkaline media. Post-XPS analyses reveal that surface Ir(VI) oxide generated at surface defective sites of Ir-Pd nanocatalysts is a possible key intermediate for OER. In acidic medium, the specific activity of Ir-Pd nanocatalysts has a positive correlation with the surface roughness of NWs > NHSs > NTs. However, the strong dissociation of surface Ir(VI) species (IrO 4 2− ) at surface defective sites is a possible obstacle for the formation of Ir(VI) oxide, which reverses the activity sequence for OER in alkaline medium.

Bifunctional Behavior of Pd/Ni Nanocatalysts on MOF‐Derived Carbons for Alkaline Water‐splitting

“…74 and 197 mV dec À 1 were recorded for Pd/Ni/MOFDC and Pd/ AT-Ni/MOFDC, respectively. Lower b a value of Pd/Ni/ MOFDC is an indication of fast H 2 O dissociation for facile OER [66][67][68]. Thus, the enhanced OER activity was confirmed for the Pd/Ni/MOFDC.…”

Strain Regulation to Optimize the Acidic Water Oxidation Performance of Atomic‐Layer IrOx

“…In recent years, massive efforts have been made to develop clean and renewable energy devices including rechargeable batteries, fuel cells, electrolyzers, etc., to reduce the fossil fuels reliance and improve our environment . Among the electrode reactions involved in these new energy technologies, electrocatalytic oxidation of water to O 2 (oxygen evolution reaction, OER) plays a critical role in the long‐term storage of electricity from renewable sources in form of molecular fuels like H 2 via water electrolysis . Recently, many high‐performance and low‐cost catalysts, such as Co‐ and Ni‐based materials, have been developed for electrochemical and photoelectrocatalytic water oxidation in alkaline media.…”

Rare-earth-regulated Ru-O interaction within the pyrochlore ruthenate for electrocatalytic oxygen evolution in acidic media

“…However, the sluggish kinetics of the anode reaction (OER) impedes the industrialization of PEM-based electrolysis [11]. Catalysts working in harsh environment especially at low pH are still limited to noble-metal-based materials such as RuO 2 and IrO 2 [12]. Theoretical studies reveal that optimal OER catalysts are supposed to possess neither too strong nor too weak binding strengths to oxygen intermediates [13].…”