Phosphorus‐Doped CuCo₂O₄ Oxide with Partial Amorphous Phase as a Robust Electrocatalyst for the Oxygen Evolution Reaction

Abstract

It is highly desirable to develop efficient and low‐cost electrocatalysts for the oxygen evolution reaction (OER) to improve the efficiency of water electrolysis. Here, we report a strategy doping with a small amount of phosphorus to make inactive and low‐cost spinel CuCo2O4 (CCO) turn into high‐efficiency and superior to the noble metal catalyst RuO2. The spinel CuCo2O4−P0.5 (CCP0.5) shows the best OER performance with a small overpotential of 290 mV at a current density of 10 mA cm−2 and a low Tafel slope of 68 mV dec−1 in an alkaline electrolyte. The phosphorus doping induces the production of an amorphous phase that provides a large number of active sites, and the synergistic effect of the crystalline phase and amorphous phase significantly improves the OER activity of CCO. It is also revealed that the conductivity of CCO is improved compared with pristine CCO. Our work highlights that non‐metallic element doping is an effective strategy to greatly enhance the OER performance of spinel transition metal oxide electrocatalysts.

Recent Progress on Bimetallic‐Based Spinels as Electrocatalysts for the Oxygen Evolution Reaction

“…However, doping with other atoms can improve the intrinsic activity and the conductivity of CuCo 2 O 4 . [ 48,139 ] Other strategies that have been explored to improve the OER performance of CuCo 2 O 4 are discussed below.…”

Engineering the Structural Defects of Spinel Oxide Nanoneedles by Doping of V for a Highly Efficient Oxygen Evolution Reaction

“…In particular, the spinel AB 2 O 4 (A and B representing transition metals) containing 3d transition metals have exhibited great potential of OER performance. , Among these spinel AB 2 O 4 , CuCo 2 O 4 has been greatly applied in supercapacitors, , electrochemical sensors, , and electrocatalysts, , due to its unique spinel structure. Unfortunately, its low electric conductivity and limitation exposure of catalytic sites seriously hinder its further improvement of OER performance . As is well known, the partial tetrahedral and octahedral interstices are occupied by the Co cations in the CuCo 2 O 4 crystal lattice, and the remaining unfilled interstices provide a chance to accommodate the migration of cations.…”

“…etc.) is a valued strategy to regulate the electronic structures and increase active sites, thus significantly boosting the electrocatalytic activity of OER. , For example, Huo et al reported the fabrication of Co 3 O 4 nanosheets with enriching oxygen vacancies by an Ar plasma engraving approach, in which the introduction of oxygen vacancies significantly improves the conductivity and accelerates the formation of extensive active sites, thus resulting in the great enhancement of OER performance . Qiu and co-workers developed a p–n heterojunction interface method to fabricate CeO 2 /Co 3 O 4 compound with abundant Co 2+ octahedral sites, which significantly enhanced its OER performance.…”

Design of Trimetallic NiMoFe Hollow Microspheres with Polyoxometalate‐Based Metal‐Organic Frameworks for Enhanced Oxygen Evolution Reaction

“…[5] But the OER is more kinetically sluggish because OER is a four-electron transfer reaction, while the HER needs only two electrons. [6] Therefore, in order to use the method of water electrolysis and efficiently convert other renewable energy into hydrogen energy, a good electrocatalyst for OER is indispensable, which can drive larger current density at low overpotential values. [7] At present, the most widely used OER catalysts are RuO 2 and IrO 2 , However, it is difficult to achieve their large-scale application because of their high costs and scarcity.…”

“…Water electrolysis consists of hydrogen evolution reaction (HER) and OER [5] . But the OER is more kinetically sluggish because OER is a four‐electron transfer reaction, while the HER needs only two electrons [6] . Therefore, in order to use the method of water electrolysis and efficiently convert other renewable energy into hydrogen energy, a good electrocatalyst for OER is indispensable, which can drive larger current density at low overpotential values [7] .…”