Molten salt-templated synthesis of ternary NiS–NiCo2O4@C composites as high performance catalysts for 4-nitro phenol reduction and supercapacitor

The integration of two transition metals with carbon materials provides a great potential to boost the catalytic and electrochemical properties of supercapacitor. However, a scalable fabrication of such composite materials remains a challenge. Here, ternary composites of NiS-NiCo2O4@C nanosheets were derived from nickel and cobalt oleate using Na2SO4 as both hard template and sulfur source. The NiS-NiCo2O4@C composites were then tested as catalysts toward rapid reduction of 4-nitrophenol (4-NP) and as electrode materials for supercapacitors. It was found that the catalytic and electrochemical properties of the composites were tuned by adjusting the ratios of Co to Ni and annealing temperature. The optimized composite showed the highest reduction rate constant for 4-NP reduction (1.78 min(-1)). In addition, this composite has also shown high specific capacitance of 1411 F g(-1) at 1 A g(-1) and 99.5% capacity retention after 2000 continuous charge-discharge cycles at a current density of 3 A g(-1), which is much higher than their respective monometallic Co and Ni composites. Furthermore, the ASC device (CN14//AC) achieved a high energy density of 37.2 W h kg(-1) at a power density of 799.9 W kg(-1), and a good cycling performance of retention(89%) after 5000 cycles. (C) 2019 Elsevier Ltd. All rights reserved.