Selective surface reconstruction of a defective iridium-based catalyst for high-efficiency water splitting

Abstract

Development of robust catalysts for electrochemical water splitting is a critical topic for the energy conversion field. Herein, a precise electrochemical reconstruction of IrTe2 hollow nanoshuttles (HNSs) is performed for oxygen and hydrogen evolution reactions (OER and HER), the two half reactions of water splitting. It is determined that the reconstruction of IrTe2 HNSs can be regulated by adjusting the potential during electrochemical dealloying, in which mild and high potentials lead to the formation of IrTe2 HNSs with metal Ir shell (D-IrTe2 HNSs) and IrOx surface (DO-IrTe2 HNSs), respectively. Detailed analyses reveal that such electrochemical reconstruction has produced abundant defects in D-IrTe2 and DO-IrTe2 HNSs. As a result of this, D-IrTe2 HNSs present a very low HER overpotential of 54 mV at a current density of 10 mA cm−2 in 1.0 m KOH. Moreover, the turnover frequency of DO-IrTe2 HNSs is 0.36 O2 s−1 at an OER overpotential of 250 mV in 0.5 m H2SO4, outperforming the most of reported Ir-based catalysts. Furthermore, the D-IrTe2||DO-IrTe2 couple exhibits promising activity for the overall water splitting in both 1.0 m KOH and 0.5 m H2SO4. This study promotes the fundamental research for the design of efficient catalysts via surface engineering.