Self-supported nanoporous Zn-Ni-Co/Cu selenides microball arrays for hybrid energy storage and electrocatalytic water/urea splitting

The phase-pure multiple ternary or quaternary metal selenides in energy boosting, have not been reported yet. Here, self-supported porous crystalline Zn-Ni-Co/Cu selenides microballs arrays were constructed by selenation of the designed tubular Cu(OH)(2) arrays decorated with ultrathin Zn-Co-Ni tri-metallic hydroxide on carbon cloth substrate. For this rational engineering, a novel precursor sample was firstly prepared by conversion of deposited Cu layer to hollow tubular Cu(OH)(2) arrays on carbon cloth, then, Zn-Co-Ni layered ternary hydroxides with a thin layer structure was deposited around this tubular arrays. The selenation with an exciting morphology change from amorphous tube to highly crystalline microballs lead to the advanced electrode materials that successfully combine the desired merits such as high conductivity, large specific surface areas, and multiple redox and electrocatalytic active sites for asymmetric supercapacitors, oxygen evolution reaction (OER), and urea oxidation reaction (UOR) applications. Interestingly, the Zn-Ni-Co/Cu microballs selenide does not demonstrate striking capacitive behaviors, when evaluated as a battery-type material for electrochemical energy storage (ESs) with the maximum capacity reaching as high as 884.6 C g(-1) (or 2211.5 F g(-1)) at 1 A g(-1) and excellent rate capability. But it exhibits competitive OER and UOR electrocatalytic performances with excellent stability, which requires a low potential of 0.312 V (vs. AgCl) to drive 100 mA cm(-2) in UOR and remarkable catalytic current of 325 mA cm(-2) at 1.6 V vs. RHE for OER in alkaline solutions, which superior than that of the reported metal selenides or oxides materials up to date.