Hollow Porous MnFe₂O₄ Sphere Grown on Elm‐Money‐Derived Biochar towards Energy‐Saving Full Water Electrolysis

Abstract

Abstract 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 MnFe 2 O 4 spheres, which are grown on natural‐abundant elm‐money‐derived biochar material to construct MnFe 2 O 4 /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. MnFe 2 O 4 /BC give a promising general strategy for preparing the effective and stable bifunctional catalysis that can be expand to multiple transition metal oxide.