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 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 IrO_x 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. © 2020 Wiley-VCH GmbH.