Selective phosphidation and reduction strategy to construct heterostructured porous nanorod of CoP coated on Mn3O4 as a bifunctional electrocatalyst for overall water splitting

Decent activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in the same electrolyte have great practical significance in the development of clean and sustainable alternative energy. Herein, for the first time, heterostructured porous nanorod of CoP nanoparticles anchored on Mn3O4 porous nanorods (Mn3O4/CoP PNRs) was fabricated via a selective phosphidation and targeted reduction strategy from MnO2/Co3O4 precursor. Due to the in-situ conversion process, an interpenetrated interface Mn-O-Co-P are formed, which may induce a strong electronic coupling effect between CoP and Mn3O4, thus improving the charge transfer and electrocatalytic activity. Well, phosphorization can also modulate the surface structure of spinel Mnx2+Mn3-x3+O4, which may enhance its electrical conductivity and inspire its activity. The hetemstructured Mn3O4/CoP PNRs exhibits superior HER and OER activity, as evidenced by low overpotentials of 43 mV (vs. HER) and 306 mV (vs. OER), to achieve a current density of 10 mA cm(-2), small Tafel slopes of 28.9 mV dec(-1 )(vs. HER) and 51.8 mV dec(-1) (vs. OER) in an alkaline medium. Impressively, an alkaline overall water-splitting electrolyzer made of this catalyst only requires a low cell voltage of 1.599 V to reach 10 mA cm(-2), which is comparable to the most cobalt phosphide-based catalysts.

Automated summary

This study successfully achieved decent activities for both HER and OER in the same electrolyte by fabricating heterostructured porous nanorods, demonstrating superior electrocatalytic performance. Phosphorization process was found to modulate the surface structure and electrical conductivity of Mn3O4/CoP PNRs, leading to enhanced activity.