NiFe2O4/Ni2P Mott-Schottky heterojunction boosts the oxygen evolution reaction in alkaline water/natural seawater

Abstract

Exploiting non-noble metal electrocatalysts for sluggish anodic oxygen evolution reaction (OER) is an essential propellant to clean hydrogen energy production from water/seawater electrochemical splitting, but still confronts a grand challenge. Recently, the metal/semiconductor interface effect has been used as a feasible implementation to achieve favorable electrocatalytic performance due to the built-in electric field. Herein, we first report the Mott-Schottky heterojunction electrocatalyst composed of metallic Ni2P and p-type semiconducting NiFe2O4, developed via a two-step hydrothermal-phosphorization method. With the strategy, the catalyst charge redistribution is owning to the self-driven electron carriers transfer in the heterointerfaces of NiFe2O4/Ni2P, leading to the formation of a built-in electric field, thereby favoring the reaction kinetics of OER. Experimental findings that NiFe2O4/Ni2P shows excellent wettability, corrosion resistance, and exceptional OER performance with a low overpotential of 230/260 mV to deliver a current density of 10 mA cm−2, and a low Tafel slope of 53.6/70.8 mV dec−1 in basic solution and natural seawater, respectively. Impressively, the NiFe2O4/Ni2P||Pt/C electrolyzer only needs 1.46/1.56 V to output 10 mA cm−2 and superior stability in water/seawater electrolyte for continuous working for 50 h NiFe2O4/Ni2P Mott-Schottky heterojunction is a promising candidate as a highly efficient OER electrocatalyst for realistic alkaline water/seawater electrolysis.