Modulation of the Electronic Structure of IrSe2 by Filling the Bi Atom as a Bifunctional Electrocatalyst for pH Universal Water Splitting

Abstract

Although IrSe2 is a superior oxygen evolution catalyst, its electronic structure lacks active sites for hydrogen production and hinders its use as a bifunctional catalyst. The intercalation of Bi atoms into the IrSe2 framework regulates its electronic structure with the improvement of performance. Herein, novel bismuth inserted iridium‐based selenide (BiIr4Se8) is synthesized via solid‐state reaction. Interestingly, BiIr4Se8 exhibits impressive activities with dual functionality in pH‐universal electrolytes. It achieves small overpotentials at 10 mA cm−2 toward hydrogen evolution (85 mV in acid and 252 mV in alkali) and oxygen evolution (379 mV in acid and 364 mV in alkali), which overmatches the benchmarking noble metal‐based electrocatalysts. When served as the bifunctional electrocatalyst to drive a water electrolyzer, BiIr4Se8 affords 10 mA cm−2 at a voltage of 1.56 and 1.52 VRHE in 0.5 m H2SO4 and 1 m KOH, far exceeding the Pt/C||RuO2 and other published materials. Theoretical calculations show that a narrow bandgap is obtained due to the induced intermediate band derived from the combination of the p orbitals of Bi atoms and structure reconstruction, which promotes the electrocatalytical performance. This research introduces a new strategy to design channel structures and sheds light on their applications for water splitting.