Multifunctional Prussian blue analogous@polyaniline core-shell nanocubes for lithium storage and overall water splitting

Developing efficient multifunctional electrode materials is highly effective to dramatically reduce the overall cost of the electrochemical devices. In this work, we for the first time demonstrate a facile strategy for preparing Prussian blue analogous@polyaniline core-shell nanocubes (denoted as PBAs@PANI) as multifunctional electrode materials for lithium storage and overall water splitting. By finely controlling the reaction parameters, PANI was uniformly coated on the surface of PBAs nanocubes and that the thickness of the PANI shell can be adjusted. The as-synthesized PBAs@PANI nanocubes yield improved electrochemical performance due to significantly enhanced charge transport, elastic buffer, and corrosion protection afforded by the PANI coating. More specifically, PBAs@PANI nanocubes show excellent lithium storage behavior with a reversible capacity of 626 mA h g^-1 compared with the uncoated PBAs (203 mA h g^-1) after 500 cycles at a high current density of 1 A g^-1. Furthermore, PBAs@PANI nanocubes can also efficiently catalyze the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and we therefore investigated their applications as bifunctional electrocatalysts (as both the anode and cathode) for overall water splitting. A current density of 10 mA cm^-2 can be gained at a low cell voltage of 1.73 V over a long-term operation in base, representing a combined overpotential of 500 mV for full water splitting. These superior performances manifest that PBAs@PANI nanocubes can serve as high-performance anode for LIBs as well as promising bifunctional electrocatalysts for overall water splitting.