Porous cobalt/tungsten nitride polyhedra as efficient bifunctional electrocatalysts for overall water splitting
JOURNAL OF MATERIALS CHEMISTRY A(2020)
摘要
The construction of porous bifunctional electrocatalysts is highly desirable for efficient overall water splitting, which however remains a challenge. Herein, porous cobalt/tungsten nitride (Co/WN) polyhedra were successfully synthesized by the growth of a polyhedral Co-W oxide precursor on Ni foam followed by a controlled nitridation as a bifunctional electrocatalyst for high-efficiency hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The porous structure of the Co/WN polyhedra can provide more reactive sites and promote mass/charge transfer. Moreover, the synergy between Co and WN can adjust the electronic structure, thus facilitating the adsorption/desorption of intermediates on the catalyst. Due to the above advantages, the optimized Co/WN polyhedra exhibit superior bifunctional performance in alkaline electrolyte with low overpotentials of 27 and 232 mV (without iR compensation) at a current density of 10 mA cm(-2) for the HER and OER, respectively. Especially, the Co/WN-600 sample shows better performance than commercial Pt/C and RuO2 at high current densities. Furthermore, the self-supported Co/WN polyhedra enable overall water splitting at a low cell voltage of 1.51 V to obtain a current density of 10 mA cm(-2) with outstanding catalytic durability.
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关键词
Water Splitting,Electrocatalysts,Nanocatalysts,Photocatalysts
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