In situ co-deposition of nickel hexacyanoferrate nanocubes on the reduced graphene oxides for supercapacitors

A facile co-precipitation strategy is developed to prepare nickel hexacyanoferrate nanocubes (NiHCF NBs) supported on the reduced graphene oxide (rGO) in the presence of poly(diallyldimethylammonium chloride) (PDDA). The NiHCF NBs are uniformly deposited on the rGO by electrostatic interaction. Their size can be tuned from 10 nm to 85 nm by changing their content from 32.6% to 68.2%. Under the optimal condition, NiHCF/PDDA/rGO hybrids are composed of 51.4% NiHCF NBs with an average size of 38 nm. The specific capacitance of NiHCF/PDDA/rGO hybrids reaches up to 1320 F g−1 at a discharge density of 0.2 A g−1, more than twice that of the pure NiHCF, as well as slight capacitance decay by 15% at 0.2 A g−1 and excellent cycling stability with 87.2% of its initial capacitance after 10,000 discharge/charge cycles. More importantly, NiHCF/PDDA/rGO hybrids exhibit an ultrahigh energy density of 58.7 Wh kg−1 at the power density of 80 W kg−1. The superior storage energy performance of NiHCF/PDDA/rGO hybrids, such as high specific capacitance, good rate capacity and long cycling stability, positions them as a promising candidate for supercapacitor materials.