Structural Anisotropy Determining The Oxygen Evolution Mechanism Of Strongly Correlated Perovskite Nickelate Electrocatalyst

The regulation of reactive centers by involving the participation of lattice oxygen has been reported as an effective strategy for lowering the reaction barrier for the oxygen evolution reaction (OER). However, the control of the OER pathway by taking advantage of the intrinsic properties of catalysts remains a challenging task. Herein, we adopt perovskite nickelate (i.e., NdNiO3 (NNO)) and establish the link between structural anisotropy and the OER catalytic mechanism. The results elucidate that NNO with (100), (110), and (111) orientations display similar oxidative states and metal-oxygen covalency characteristics but distinct OER activities following the order of (100) > (110) > (111). Density function theory (DFT) results confirm that film orientation is a critical determinant of the reaction mechanism. The OER on (100)-NNO favors proceeding via a lattice-oxygen-mediated mechanism (LOM). In contrast, the reaction on (110)-NNO and (111)-NNO follows the adsorbate evolution mechanism (AEM). The anisotropic oxygen vacancy formation energy and stability are strongly correlated to the reaction mechanism and performance, which can be described in brief by the metal-oxygen bond valence. Our results are a step toward achieving the long-sought convenient approach to tune the OER mechanism, which is applicable for a wide range of sustainable energy-related devices.