Controlled synthesis of porous CaCo2O4 nanoflowers and their multifunctional applications for lithium ion batteries and oxygen evolution reaction

Abstract

A facile two-step method is developed to synthesize three dimensional (3D) hierarchical CaCo2O4 architectures as high-performance electrode materials for lithium ion batteries (LIBs) and oxygen evolution reaction (OER). Our strategy involves a simple poly(vinylpyrolidone) (PVP)-assisted hydrothermal route and subsequent thermal treatment to produce flowerlike CaCo2O4 nanostructures with a size of ∼500 nm, which is constructed by some neighboring vertical nanoplates. Whereas, the absence of PVP results in the formation of CaCo2O4 microspheres, further indicating the vital role of PVP in favor of the oriented crystal growth of Co-based oxides. Benefited from the unique structural features, the resultant CaCo2O4 nanoflower presents excellent cycling stability (∼560 mAh g−1 after 100 cycles at 50 mA g−1) and remarkable rate capability. Apart from superior lithium storage properties, more strikingly, CaCo2O4 nanoflower demonstrates a promising candidate as a noble metal-free electrocatalyst for oxygen evolution reaction, which will spur us to find more novel functional nanomaterials for wide applications.