Interfacial modification of Co(OH)2/Co3O4 nanosheet heterostructure arrays for the efficient oxygen evolution reaction

Abstract

The development of efficient, stable and low-cost oxygen evolution reaction (OER) catalysts in anodes is essential for the production of hydrogen resources by electrolyzing water. Cobalt hydroxide (α-Co(OH)₂) is one of the most encouraging electrocatalysts for the OER under alkaline conditions, but its catalytic activity is still unsatisfactory possibly due to its unfavorable electronic structure. The construction of heterogeneous catalysts has been considered as an effective strategy to change the interface and modulate the electronic structure of electrocatalysts, resulting in improved activities. Herein, novel self-supported α-Co(OH)₂ coated Co₃O₄ nanosheet arrays on conductive carbon cloth have been constructed and fabricated via a simple electrodeposition method (α-Co(OH)₂/Co₃O₄/CC), serving as efficient catalysts for the OER. The as-prepared heterostructure with optimal proportions of α-Co(OH)₂ to Co₃O₄ exhibits an enhanced overpotential of 275 mV at 10 mA cm⁻² (322 mV for α-Co(OH)₂/CC and 359 mV for Co₃O₄/CC), a low Tafel slope of 76 mV dec⁻¹ and excellent durability for 22 h. The further electrochemical results show that the formation of heterostructure can optimize the electronic structure of the catalysts through interfacial coupling effect, improve the charge transfer ability and increase the electrochemical active sites, all of which are beneficial to the OER performance enhancement. This work not only develops a highly efficient and stable non-precious metal catalyst toward the OER, but also opens up new ways for boosting the performance by regulating the electronic structure through interface engineering of electrocatalysts and beyond.