Hollow Porous MnFe2 O4 Sphere Grown on Elm-Money-Derived Biochar towards Energy-Saving Full Water Electrolysis.

The development of inexpensive and efficient bifunctional electrocatalysts is significant for widespread practical applications of overall water splitting technology. Herein, a one-pot solvothermal method is used to prepare hollow porous MnFe2 O4 spheres, which are grown on natural-abundant elm-money-derived biochar material to construct MnFe2 O4 /BC composite. When the overpotential is 156 mV for both the oxygen evolution reaction and the hydrogen evolution reaction, the current density reaches up to 10 mA cm-2 , and its duration is 10 h. At 1.51 V, the overall water decomposition current density of 10 mA cm-2 can be obtained in 1 m KOH. This work proves that elm-money-derived biochar is a valid substrate for growing hollow porous spheres. MnFe2 O4 /BC give a promising general strategy for preparing the effective and stable bifunctional catalysis that can be expand to multiple transition metal oxide.