Chlorine-doped α-Co(OH) hollow nano-dodecahedrons prepared by a ZIF-67 self-sacrificing template route and enhanced OER catalytic activity.

Hollow α-Co(OH) and Cl-doped α-Co(OH) nano-dodecahedrons were successfully synthesized via a ZIF-67-assisted template route in the absence/presence of NaCl. The reactions were carried out in a Teflon-lined stainless-steel autoclave at 40 °C for 4 h, employing dodecahedral ZIF-67 and hexamethylenetetramine (HMT) as the reactants. The as-obtained hollow nano-dodecahedrons were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray photoelectron energy, EDS mapping and N sorption-desorption technologies. Electrochemical measurements showed that both α-Co(OH) and Cl-doped α-Co(OH) hollow nano-dodecahedrons displayed excellent catalytic activities for the oxygen evolution reaction (OER) and Cl-doped α-Co(OH) hollow ones possessed stronger electrocatalytic performances. To deliver a current density of 10 mA cm, Cl-doped α-Co(OH) hollow nano-dodecahedrons required a low overpotential of 298 mV, which is smaller than most reported α-Co(OH) catalysts. Also, the as-obtained hollow catalyst still had excellent OER cycling stability and durability. After 1000 CV cycles, the overpotential merely slightly increased. Continuously catalyzing at the current density of 10 mA cm for 40 h, the voltage only increased ∼2.5%.