Refined construction of heterophase boundary on CoCO3@Cobalt boride nanocomplexes for supercapacitor and electrocatalysis

Heterostructures comprising crystalline cores and amorphous shells are pervasively utilized in electrochemical storage and conversion due to their distinctive physical and chemical attributes. In this study, we present a novel CoCO3@Co-B nanocomposite as a tri-functional electrode for supercapacitors and alkaline water electrolysis. The material is produced via a straightforward hydrothermal process, followed by an in-situ growth treatment. The core-shell structure of crystalline CoCO₃-amorphous Co-B exhibits remarkable specific capacitance and commendable hydrogen and oxygen evolution performance. The optimized CoCO3@Co-B electrode exhibits remarkable specific capacitance (352 F g−1 @ 0.5 A g−1) and superior cycling stability (78 % @ 5 A g−1 after 10,000 cycles). Additionally, the CoCO3@Co-B//activated carbon hybrid supercapacitor device exhibits a considerable specific capacitance (42.1 F g−1 @ 0.5 A g−1). The CoCO3@Co-B electrode displays excellent OER/HER performance, with Tafel slopes of 82.6 and 116 mV dec−1, respectively, which are superior to the original CoCO3 values. This kind of active material exhibits a crystalline-amorphous contact, which reduces the energy barrier of electrochemical reactions and forms a built-in electric field, thereby increasing the number of active sites and enhancing electron transmission. As an advanced electrode material, CoCO3@Co-B holds immense potential for future development and research.