Iridium-Incorporated Strontium Tungsten Oxynitride Perovskite for Efficient Acidic Hydrogen Evolution

Abstract

Heteroanionic materials exhibit great structural diversity with adjustable electronic, magnetic, and optical properties that provide immense opportunities for materials design. Within this material family, perovskite oxynitrides incorporate earth-abundant nitrogen with differing size, electronegativity, and charge into oxide, enabling a unique approach to tuning metal-anion covalency and energy of metal cation electronic states, thereby achieving functionality that may be inaccessible from their perovskite oxide counterparts, which have been widely studied as electrocatalysts. However, it is very challenging to directly obtain such materials due to the poor thermal stability of late transition metals coordinated with N and/or at high valence states. Herein, we introduce an effective strategy to prepare a perovskite oxynitride with a small fraction of sites substituted with Ir and adopt it as the first electrocatalyst in this material family, thereby enabling high activity and efficient utilization of precious metal content. From a series of characterization techniques, including X-ray absorption spectroscopy, atomic resolution electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, we prove the successful incorporation of Ir into a strontium tungsten oxynitride perovskite structure and discover the formation of a unique Ir–N/O coordination structure. Benefitting from this, the material exhibits a high activity toward the hydrogen evolution reaction, which exhibits an ultralow overpotential of only 8 mV to reach 10 mA/cm2 geo in 0.5 M H2SO4 and 4.5-fold enhanced mass activity compared to commercial Pt/C. This work opens a new avenue for oxynitride material synthesis as well as pursuit of a new class of high-performance electrocatalysts.

Dual-Cation-Coordinated CoFe-Layered Double-Hydroxide Nanosheets Using the Pulsed Laser Ablation Technique for Efficient Electrochemical Water Splitting: Mechanistic Screening by In Situ/Operando Raman and Density Functional Theory Calculations

“…Thus, an electrocatalyst that is inexpensive, abundant, highly stable, and efficient is required. Nonetheless, the major drawback of water electrolysis is the anodic OER process, which follows a four-electron transfer multistep uphill reaction, while the HER is a two-electron process. − Thus, the OER is considered a kinetically sluggish process. To counter this issue, the development of a highly stable and active electrocatalyst is necessary to lower the overpotential and increase the OER rate.…”

Nickel–Cobalt Selenide Electrocatalytic Electrode toward Glucose Oxidation Coupling with Alkaline Hydrogen Production

“…Transition metal-based selenides, which usually have low cost and relatively high electrical conductivity, are considered as promising electrocatalysts for various reactions such as HER, − OER, − and oxygen reduction reaction. , Here, we report an efficient nonprecious-metal electrocatalyst, nickel–cobalt selenide (NiCoSe x ) nanoplates supported on nickel foam, as a bifunctional catalyst for the anodic GOR and the cathodic HER. A potential of as low as 1.41 V vs RHE is required for the glucose oxidation at the anode to reach a high catalytic current density of 500 mA cm –2 .…”

Amorphous RuO2 Catalyst for Medium Size Carboxylic Acid to Alkane Dimer Selective Kolbe Electrolysis in an Aqueous Environment**

“…Electrochemical impedance spectroscopy (EIS) is conducted to investigate the charge transfer efficiency of samples. As shown in Figure S13b, a‐RuO 2 exhibits a much smaller charge transfer resistance than that of n‐RuO 2 , which indicates the introduction of oxygen vacancies enhances the charge transfer rate [27] . In summary, the…”

“…As shown in Figure S13b, a-RuO 2 exhibits a much smaller charge transfer resistance than that of n-RuO 2 , which indicates the introduction of oxygen vacancies enhances the charge transfer rate. [27] In summary, the amorphous structure and abundant oxygen vacancies indeed optimize the electronic structure and stability of the samples and improve the catalytic efficiency. [28]…”