Engineering Multifunctional Stratified LiCoO₂ Catalysts: Structural Disorder to Microstructural Exfoliation

Abstract

The stratified nature of LiCoO2 (LCO) makes such materials suitable for rechargeable Li-ion batteries. The existing synthesis technology for LCO, however, results in a low surface area, low activity, and a limited density of active sites, which limit its applications in catalysis, in which the material’s functionality is determined by the reactions that occur on its surface. The present work reports a simplified and high-yield strategy for using bulk LCO in multifunctional two-dimensional (2D) catalysts. The recovery involves ordered and/or disordered leaching of Li+ as a result of H+ intercalation and formation of catalytically active oxygen vacancies at high concentrations (∼32 atom %). This is followed by exfoliation of the LCO into porous nanosheets through intercalation of tetramethylammonium hydroxide. The catalytic performance of the etched and exfoliated LCOs was investigated; the 1 M HCl-etched LCO exhibited the highest photocatalytic dye degradation (99.9%) under simulated solar light, while the etched and fully exfoliated LCO showed outstanding CO oxidation, with a T 90% = 140 °C, which is significantly lower than that of the bulk LCO catalyst (T 90% = 360 °C).