Facile synthesis of ultrathin Co(OH)NO nanosheets and their electric-field assisted transformation into a defect-rich CoO/CoOOH heterostructure for efficient oxygen evolution

Facile preparation of low-cost electrocatalysts for an efficient oxygen evolution reaction (OER) is significant but remains a big challenge. Herein, a novel and facile strategy for transforming intrinsic non-stoichiometric ultrathin Co 5 (O 9.48 H 8.52 )NO 3 nanosheets into oxygen-vacancy enriched Co 3 O 4 /CoOOH heterostructure nanosheets for an efficient OER was developed. The as-synthesized Co 3 O 4 /CoOOH heterostructure nanosheets displayed excellent OER performances, showing an extremely low overpotential of 260 mV at a current density of 10 mA cm −2 , a relatively small Tafel slope of 52 mV dec −1 , and a long-term durability of at least 20 h. This work provides a new way for the production of oxygen vacancies on metal (oxy)hydroxide nanosheets through electric-field assisted in situ transformation of non-stoichiometric metal oxyhydroxide nanosheets. Electric-field assisted transformation of ultrathin Co 5 (O 9.48 H 8.52 )NO 3 nanosheets into a defect-rich Co 3 O 4 /CoOOH heterostructure for efficient oxygen evolution.