Highly Synergistic Co3+ and Pyridinic-N-Rich Bifunctiona Electrocatalyst for Ultra-Low Energy-Driven Effective Hydrogen Production and Urea Oxidation

Abstract

Metal-organic framework (MOF)-derived electrocatalysts exhibit enhanced electrochemical water splitting with significant durability. However, they cannot drive the required current density at a lower overpotential (eta) compared to other benchmark catalysts. To overcome the lack of efficient catalytic activity, Co3O4-embedded nitrogen-doped carbon (NC) is fabricated on NiO nanosheets derived from an in situ synthesized Co MOF with an electrodeposited (Ni(OH)(2)) layer. The electrocatalyst developed herein comprises many Co3+, Ni3+, and pyridinic-N-exposed active centers and exhibits an excellent synergistic effect between the metal oxide-NC-metal oxide, facilitating a highly efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Owing to the highly intimate contact between the electrocatalyst layers, rapid electron transfer occurs and a current density of 10 mA cm(-2) is produced in the HER and OER at eta of 73 and 110 mV, respectively, with excellent mass activity and high turnover frequency. However, urea-assisted water electrolysis achieves current densities of10 and 100 mA cm(-2) at cell voltages of just 1.31 and 1.49 V, respectively, for the two-electrode-based system, with an extremely stable durability of 212 h (1.49 V). Co3O4@NC/NiO parallel to Co3O4@NC/NiO has a considerably better urea electrolysis performance than other benchmark electrocatalysts.