Atypical performance of CoO-accelerated interface tweaking in hierarchical cobalt phosphide/oxide@P-doped rGO heterostructures for hybrid supercapacitors

Designing two-dimensional (2D) heterostructures based on suitable energy materials is a promising strat-egy to achieve high-performance supercapacitors with hybridized transition metal and carbonaceous -based electrodes. The influence of each component and its content on the capacitor performance necessi-tates deeper insights. In this study, a 2D/2D heterostructure made of hierarchical pseudocapacitive cobalt phosphide/oxide and P-doped reduced graphene oxide (PrGO) nanosheets (CoP/CoO@PrGO) was fabricated using porous zeolitic-imidazolate framework precursor. The decoration of 2D leaf-like CoP/CoO hybrid onto PrGO could create a unique interface with a large number of active sites, CoO-driven creation of pseudoca-pacitive surface POx species, and high P content (-3 at.%) in PrGO, thus promoting the Faradaic reaction, electrical conductivity, and overall charge storage. This framework yields a high specific capacitance of 405 F g-1 at 5 A g-1 and excellent cycling stability (over 100 % after 10,000 cycles), superior to those of pris-tine CoP@PrGO (300 F g-1 at 5 A g-1). Furthermore, the fabricated asymmetric supercapacitor delivers rea-sonable energy density of 4.2 Wh kg-1 at a power density of 785 W kg-1 and cycling stability of-100 % after 10,000 cycles. Therefore, CoP/CoO@PrGO with its unique interfacial properties can promote the develop-ment of heterostructure electrode for high-performance supercapacitors.(c) 2022 Elsevier Inc. All rights reserved.