Heterointerface-engineered 2D/2D layered heterojunction with electronic coupling for energy storage

Co(OH)₂ layers were grown on nickel foam by an instantaneous nucleation mechanism regulated by cathodic electrodeposition. Treating Co(OH)₂ layers as the template, Ni(OH)₂ layers were cladded onto to form Co(OH)₂/Ni(OH)₂ heterojunction. The resultant self-supported binder-free architectures with abundant active sites and reduced aggregation facilitate faradaic redox reactions and shorten electron transport distance. The heterointerface-engineered Co(OH)₂/Ni(OH)₂ architecture with interfacial electronic coupling as electrodes highlighted its merits by delivering an areal capacity of 1965 mC cm⁻² at 1 mA cm⁻², a high specific capacity of 444 C g⁻¹, and a specific capacitance of 889 F g⁻¹ at 1 A g⁻¹. Moreover, the electrode demonstrated its chemical stability and structural endurance, with an 89.5 % retention of specific capacity at the 5000 ^th cycle. Additionally, the hybrid device assembled with Co(OH)₂/Ni(OH)₂//activated carbon composition delivered a specific capacity of 181 C g⁻¹ at 1 A g⁻¹, a maximum specific energy of 53.1 Wh kg⁻¹ at 1 A g⁻¹, and an appreciable specific power of 16.56 kW kg⁻¹ at 20 A g⁻¹. The proposed strategy takes advantage of yielding replicated two-dimensional sheets (2D) with interfacial electronic coupling, ample active sites, and high synergy between the two layers, which help in designing high-energy electrochemical storage devices.