High‐Performance Overall CO<sub>2</sub> Splitting on Hierarchical Structured Cobalt Disulfide with Partially Removed Sulfur Edges
Zhen Han, Qi Hu, Cheng Zhong, Guomin Li, Xiaowan Huang, Ziyu Wang, Hengpan Yang, Xiangzhong Ren, Qianling Zhang, Jianhong Liu, Chuanxin He
Abstract
Abstract The ability to develop bifunctional electrocatalysts for concurrent CO 2 reduction reaction (CO 2 RR) and oxygen evolution reaction (OER) is the key to the practical application of CO 2 splitting to produce CO. However, this remains a grand challenge. Herein, a robust strategy to rationally craft hierarchical structured bifunctional electrocatalysts composed of 3D CoS 2 nanocages interconnected on 2D CoS 2 nanosheet arrays (denoted hierarchical CoS 2 nanocages) for high‐performance CO 2 splitting is developed. The subsequent calcination removes the partial S edges of CoS 2 , thereby strongly suppressing the hydrogen evolution reaction (HER) of CoS 2 . By combining theoretic and experimental results, for the first time, it is discovered that the plane S of CoS 2 , instead of S edges, are highly active for CO 2 RR but inactive for HER, rendering the plane S as ideal active sites for CO 2 RR. Intriguingly, the composition tuning via calcination and the presence of a hierarchical architecture confer hierarchical CoS 2 nanocages respective outstanding CO 2 RR and OER performance. Notably, the hierarchical CoS 2 nanocages can be exploited as bifunctional electrocatalysts for overall CO 2 splitting to yield the current density of 1 mA cm −2 at a small cell voltage of 1.92 V, much lower than the widely reported values (>2.5 V).