Porous Cube-Shaped Nicos X /Cos2 Acts as Tri-Functional Catalyst for Zn-Air Battery and Overall Water Splitting

Porous cubic NiCoS x /CoS 2 composite catalyst was successfully prepared on the basis of K 3 [Co(CN) 6 ] 2 . First, Ni 2+ is substituted for K + in the K 3 [Co(CN) 6 ] 2 to prepare the binary metal ion precursor of Ni 3 [Co(CN) 6 ] 2 . Afterwards, coating Co(OH) 2 on the surface of Ni 3 [Co(CN)6] 2 can not only maintain the cubic structure of Prussian blue analogue, but also build a composite interface between two phase. After Ni 3 [Co(CN) 6 ] 2 /Co(OH) 2 precursor is sulfided, a porous NiCoS x /CoS 2 composite catalyst material with cubic structure is obtained. NiCoS x /CoS 2 catalysts showed excellent oxygen evolution reactions and oxygen reduction reactions. The overpotential was only 310 mV to achieve a current density of 20 mA cm -2 and the half-wave potential can reach 0.80 V. During the exploration of oxygen evolution reaction, the catalyst exhibited 253 mV overpotential at 10 mA cm −2 . When used this catalyst in Zn-air batteries as cathode, it showed excellent cycle stability (210 h) and small voltage gap (0.80 V) at 5 mA cm -2 . Meanwhile, soft-pack flexible batteries assembled with the NiCoS x /CoS 2 can be charged and discharged stably at any bending angle