Constructing a multi-bishelled cobalt-based electrocatalyst for the oxygen evolution reaction in CO 2 electrolysis

Electrochemical reduction of CO 2 into value-added chemicals has been envisioned as a promising strategy to alleviate the issue of increasing CO 2 emissions. However, the sluggish oxygen evolution reaction (OER), as the anodic reaction, typically consumes approximately 90% of the electricity input, necessitating the development of an efficient OER for energy-saving purposes. Herein, we developed a unique heterostructure of multi-double (bi)-shelled Co-based spheres via a facile template-free method, in which each bi-shelled structure is composed of Co 9 Se 8 /Co 9 S 8 /CoO (Co-S-Se) with a symmetric configuration. These heterogeneous nanospheres possess both sufficient heterointerfaces and a high density of active sites and exhibit excellent OER activity in alkaline media with a low overpotential of 226 mV at 10 mA cm −2 , a small Tafel slope of 46.5 mV dec −1 , and long-term durability over 15 h. As a proof and concept, when coupled with a cathodic CO 2 reduction reaction, the electrochemical performance of Pd nanosheets (NSs) for CO 2 reduction can be significantly enhanced in terms of product selectivity and energy input. Our study might provide insight into the development of efficient OER electrocatalysts for practical CO 2 reduction reactions.