Selective Surface Reconstruction of a Defective Iridium‐Based Catalyst for High‐Efficiency Water Splitting

Development of robust catalysts for electrochemical water splitting is a critical topic for the energy conversion field. Herein, a precise electrochemical reconstruction of IrTe 2 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 IrTe 2 HNSs can be regulated by adjusting the potential during electrochemical dealloying, in which mild and high potentials lead to the formation of IrTe 2 HNSs with metal Ir shell (D‐IrTe 2 HNSs) and IrO x surface (DO‐IrTe 2 HNSs), respectively. Detailed analyses reveal that such electrochemical reconstruction has produced abundant defects in D‐IrTe 2 and DO‐IrTe 2 HNSs. As a result of this, D‐IrTe 2 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‐IrTe 2 HNSs is 0.36 O 2 s −1 at an OER overpotential of 250 mV in 0.5 m H 2 SO 4 , outperforming the most of reported Ir‐based catalysts. Furthermore, the D‐IrTe 2 ||DO‐IrTe 2 couple exhibits promising activity for the overall water splitting in both 1.0 m KOH and 0.5 m H 2 SO 4 . This study promotes the fundamental research for the design of efficient catalysts via surface engineering.