Nanosheet Superhydrophobic Porous Coordination Polymers (NSPCPs) for Distinctive Electrochemical Water Splitting

We achieved three nanosheet superhydrophobic porous coordination polymers (NSPCPs), [Zn4(μ3-OH)2(BTMB)2], (PESD-1@nanosheet), and [Zn2M2(μ3-OH)2(BTMB)2], (PESD-2 and 3@nanosheets) (M = Co and Ni), by the chemical exfoliation method. The formation of these three NSPCPs was confirmed by PXRD, SEM, TEM, EDAX, etc. The contact angles of PESD-1, 2, and 3@nanosheets are 157.9, 164.1, and 162.4°, respectively, which enhanced the hydrophobicity due to the high surface area compared to that of bulk PESD-1, 2, and 3 (155.5, 159.3, and 160.8°, respectively). Moreover, in this study, we also report a unique and first study of electrochemical water splitting by superhydrophobic materials, in contrast to hydrophobic surfaces, which usually do not involve catalytical splitting of water. These three PESD-1, 2, and 3@nanosheets exhibit hydrogen evolution reactions (HERs) with overpotentials of 1157, 728, and 835 mV and oxygen evolution reactions (OERs) with overpotentials of 1450, 550, and 1070 at 10 mA cm–2 in alkaline electrolytes, respectively. Furthermore, they also exhibit good catalytical stability for more than 26 h, which indicates the good recyclability of the catalysts.