MOF-derived Zn–Co–Ni sulfides with hollow nanosword arrays for high-efficiency overall water and urea electrolysis

Water electrolysis is a promising technology to produce hydrogen but it was severely restricted by the slow oxygen evolution reaction (OER). Herein, we firstly reported an advanced electrocatalyst of MOF-derived hollow Zn–Co–Ni sulfides (ZnS@Co9S8@Ni3S2-1/2, abbreviated as ZCNS-1/2) nanosword arrays (NSAs) with remarkable hydrogen evolution reaction (HER), OER and corresponding water electrolysis performance. To reach a current density of 10 mA cm−2, the cell voltage of assembled ZCNS-1/2//ZCNS-1/2 for urea electrolysis (1.314 V) is 208 mV lower than that for water electrolysis (1.522 V) and stably catalyzed for over 15 h, substantially outperforming the most reported water and urea electrolysis electrocatalysts. Density functional theory calculations and experimental result clearly reveal that the properties of large electrochemical active surface area (ECSA) caused by hollow NSAs and fast charge transfer resulted from the Co9S8@Ni3S2 heterostructure endow the ZCNS-1/2 electrode with an enhanced electrocatalytic performance. This research will provide certain reference to design and synthesize MOF-derived trimetallic sulfides as efficient and stable electrocatalyst for enhanced water and urea electrolysis. [Display omitted] •A series of ZCNS hybrid materials were successfully prepared.•The ZCNS-1/2//ZCNS-1/2 presents superior electrochemical water splitting performance with 1.522 V to drive 10 mA cm−2.•This research will provide certain reference to design MOF-derived sulfides for water and urea electrolysis.