Abstract:

In an electrocatalyst with a heterointerface structure, the different interfaces can efficiently adjust the catalyst's conductivity and electron arrangement, thereby enhancing the activity of the electrocatalyst. Ultrathin and smaller NiFe LDH was successfully constructed on the surface of SnO₂ nanosheet supported NF by layer by layer assembly, and exhibits lower overpotential of 234 mV at a current density of 10 mA cm^-2, which only increases by 6.4% even at a high current density of 100 mA cm^-2. The excellent OER activity of catalyst is attributed to the contribution of the semiconductor SnO₂ electron transport layer. Through experiments and characterization, 3d structure SnO₂ nanosheets control the growth of ultra-thin nickel-iron, the hierarchical interface between SnO₂ and NiFe LDH can change the electron arrangement around the iron and nickel active centers at the interface, resulting the valence states of iron slightly increased and Ni³⁺ content increased. The result will promote the oxidation of water. Meanwhile, the SnO₂ semiconductor as electron transport layer is conducive to trapping electrons generated in oxidation reaction, promoting electrons transferring from the NiFe LDH active center to the Ni substrate more quickly, and enhance the activity of NiFe LDH. It also shows excellent activity in an electrolyte solution containing 0.5 M methanol and 1 M KOH, and only 1.396 V (vs. RHE) is required to drive a current density of 10 mA cm^-2.

Key words: SnO₂ nanosheet, Electron transport layer, Heterointerface structure, Water oxidation, Methanol oxidation, Ultrathin NiFe LDH