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A novel ternary hybrid of carbon nanotubes/graphitic carbon nitride nanosheets/gold nanoparticles was prepared and used as robust substrate electrodes for fabricating membrane-less glucose/O2 enzyme biofuel cells (EBFCs), and a remarkably improved power output was observed for the prepared EBFC.

[Display omitted] Developing the high-performance supercapacitors is overwhelmingly dependent on the composition design and structure tailoring of electrode materials. By a one-step solution method, the composite of carbon dots/Prussian blue analogues nanocubes-incorporated three-dimensional Ni foams was prepared and used as a self-standing positive electrode for hybrid electrochemical capacitors (HEC). Aside from the role of Ni source for Prussian blue analogues (PBA), Ni foams acts as 3D conductive supports, making electrolytes more accessible to the internal surface of electrode. Meanwhile, carbon dots can be absorbed for the formation of carbon dots/PBA nanocubes on Ni foams surfaces, offering optimized interfaces for the interactions between electrodes and electrolytes and relieving the decomposition of PBA in alkaline electrolyte. With these merits, the carbon dots/Prussian blue analogues nanocubes-Ni foams electrode in the hybrid electrolyte of 0.5 M KOH and 1.3 M Na 2 SO 4 exhibits a maximum specific capacity of 659 C g−1 at current density of 0.5 A g−1 and 344 C g−1 even under large current density of 5 A g−1. An extended working potential window of 1.8 V, high energy density of 65 Wh kg−1 and high power density of 4.052 kW kg−1 as well as improved cyclic stability are also achieved in the assembled HEC. This study builds a boulevard to improve the application potential of PBA in HEC, which will be beneficial for the development of supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] The exploitation of high-performance electrode materials is significant to develop supercapacitors with satisfied energy and power output properties. In this study, a g-C 3 N 4 /Prussian-blue analogue (PBA)/Nickel foam (NF) with hierarchical micro/nano structures was developed by a simple salts-directed self-assembly approach. In this synthetic strategy, NF acted as both 3D macroporous conductive substrate and Ni source for PBA formation. Moreover, the incidental salt in molten salt-synthesized g-C 3 N 4 nanosheets could regulate the combination mode between g-C 3 N 4 and PBA to generate interactive networks of g-C 3 N 4 nanosheets-covered PBA nano-protuberances on NF surfaces, which further expended the electrode/electrolyte interfaces. Based on the merits from this unique hierarchical structure and the synergy effect of PBA and g-C 3 N 4 , the optimized g-C 3 N 4 /PBA/NF electrode exhibited a maximum areal capacitance of 3366 mF cm−2 at current of 2 mA cm−2, as well as 2118 mF cm−2 even under large current of 20 mA cm−2. The solid-state asymmetric supercapacitor using g-C 3 N 4 /PBA/NF electrode possessed an extended working potential window of 1.8 V, prominent energy density of 0.195 mWh cm−2 and power density of 27.06 mW cm−2. Compared to the device with pure NiFe-PBA electrode, a better cyclic stability with capacitance retention rate of 80% after 5000 cycles was also achieved due to the protective effect of g-C 3 N 4 shells on the etching of PBA nano-protuberances in electrolyte. This work not only builds a promising electrode material for supercapacitors, but also provide an effective way to apply molten salt-synthesized g-C 3 N 4 nanosheet without purification. [ABSTRACT FROM AUTHOR]