Hierarchical Hollow CoWO 4 -Co(OH) 2 Heterostructured Nanoboxes Enabling Efficient Water Oxidation Electrocatalysis.

Rational design and construction of well-defined hollow heterostructured nanomaterials assembled by ultrathin nanosheets overtakes crucial role in developing high-efficiency oxygen evolution reaction (OER) electrocatalysts. Herein, a reliable metal-organic framework-mediated and cation-exchange strategy to tune the geometric structure and multicomponent heterostructures has been proposed for the fabrication of hollow CoWO 4 -Co(OH) 2 hierarchical nanoboxes assembled by rich ultrathin nanosheets. Benefiting from the hierarchical hollow nanostructure, the CoWO 4 -Co(OH) 2 nanoboxes offer plenty of metal active centers available for reaction intermediates. Moreover, the well-defined nanointerfaces between CoWO 4 and Co(OH) 2 can function as the bridge for boosting the efficient electron transfer from CoWO 4 to Co(OH) 2 . As a consequence, the optimized CoWO 4 -Co(OH) 2 nanoboxes can exhibit outstanding electrocatalytic performance toward OER by delivering 10 mA cm -2 with a low overpotential of 280 mV and a small Tafel slope of 70.6 mV dec -1 as well as outstanding electrochemical stability. More importantly, this CoWO 4 -Co(OH) 2 heterostructured nanocatalyst can couple with Pt/C to drive overall water splitting to achieve 10 mA cm -2 with a voltage of 1.57 V.