Large-current-stable bifunctional nanoporous Fe-rich nitride electrocatalysts for highly efficient overall water and urea splitting

Designing highly active electrocatalyst for both the oxygen evolution and urea oxidation reactions (OER and UOR) with good durability at large current density is very significant for greatly reducing the power consumption of water electrolysis and wastewater degradation. However, very few electrocatalysts possess simultaneously outstanding catalytic activities and large-current durability for both the oxygen evolution and urea oxidation reactions. Here we report an bifunctional nanoporous iron-rich nitride hybrid electrocatalyst possessing extraordinary catalytic OER and UOR activities as evidenced by extremely small potentials of 1.518 and 1.372 V with impressive long-term durability at a current density of 500 mA/cm2 for both OER and UOR in base, respectively. This is one of the best electrocatalysts embedding excellent OER and UOR properties in a single electrocatalyst thus far. In particular, combined with an efficient NiMoO4-H2 catalyst for the HER, we have actualized the commercially viable current density of 500 mA/cm2 at 1.623 V and 1.472 V for overall water electrolysis and urea electrolysis with outstanding long-term durability, respectively, outperforming most of the water or urea electrolysers reported hitherto. This work offers a novel approach to develop multifunctional electrocatalysts from earth-abundant elements for energy-efficient hydrogen production and pollution treatment of urea-rich wastewater.