Construction of heterostructured CoP/CN/Ni: Electron redistribution towards effective hydrogen generation and oxygen reduction

Abstract Cobalt phosphide (CoP) with its platinum-group-metal like catalytic features has triggered substantial concerns on electrocatalytic hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) under acidic and alkaline conditions. However, the electrocatalytic rate on CoP is restricted because of the reaction intermediates binding to its surface strongly, leading to sluggish reaction kinetics and unsatisfied catalytic performance. Herein, we describe a ternary heterostructured CoP/CN/Ni catalyst with oriented electron modulation effect to boost its electrocatalytic activity, where the electronic structure of the outer CoP is modulated by the endowed electrons from underlying Ni nanoparticles, which are encapsulated and protected by 2∼3 N-doped carbon (CN) layers from oxidation and corrosion in harsh environment. Theoretical calculations reveal that the electron redistribution effect could decrease the adsorption energy of hydrogen (ΔGH*) on CoP from -0.25 eV to -0.1 eV. Benefiting from such electron modulation, CoP/CN/Ni only needs overpotentials of 66 mV in 0.5 M H2SO4 and 106 mV in 1 M KOH for HER to afford a current density of 10 mA cm-2 and presents the comparable ORR activity with Pt/C in 0.1 M KOH. Besides, the unique structure also endows CoP/CN/Ni with superior electrocatalytic stability for HER and ORR.