Microwave-pulse synthesis of tunable 2D porous nickel-enriched LaMnxNi1−xO3 solid solution for efficient electrocatalytic urea oxidation

Abstract

Amidst the pressing demand for carbon neutrality and clean energy policies, the electrocatalytic urea oxidation reaction (UOR) has gained attention as an efficient and environmentally friendly energy conversion pathway. High-valence/content two-dimensional (2D) nickel-based ABO₃ perovskite oxides, particularly LaNiO₃, are highlighted for their elevated intrinsic catalytic activity and rich electronic configuration advantages. To enhance the intrinsically limited conductivity of LaNiO₃, a modified strategy involving B-site substitution can be used to construct a solid solution structure, significantly improving the electronic configuration. However, as Ni is the primary active site for the UOR, substituting the B-site will create a trade-off between enhancing electron migration and decreasing active site content. Specifically, conventional synthesis methods with a slow-entropy-change pose challenges in precise control over atomic ratios and 2D structure design, hindering elucidation of the impact mechanism of the electronic configuration on UOR performance. Herein, we utilized the microwave-pulse method for rapid synthesis of highly tunable 2D porous nickel-enriched LaMn_xNi_1−xO₃ perovskite. Leveraging transient high-temperature and high-energy conditions, we achieved rapid one-step equilibrium between 2D porous structure design and precise control of solid solution atomic ratios. This strategy allows for the controlled synthesis of 2D nickel-enriched solid solutions with excellent conductivity and UOR activity, while effectively avoiding the generation of by-products, providing a detailed analysis of the UOR activity mechanism dependent on distinct electronic configurations. The synthesized LaMn_0.2Ni_0.8O₃ structure exhibits optimal UOR performance. This strategy provides a new avenue for the design of more unique structured nickel-based solid solutions and the investigation of their structure–performance relationships in the electrocatalytic UOR.