Huimin Chen¹, Min Wang^1,*, Kaicai Fan¹, Linghui Kong¹, Honghao Lv¹, Wenzhen Li², Guangbo Liu¹, Luhua Jiang^1,*

¹ Nanomaterials and Electrocatalysis Laboratory, College of Materials and Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, P. R. China

² Department of Chemical & Biological Engineering, Iowa State University, Ames, IA 50011-1098, Unites States.

* E-mail addresses: wmin@qust.edu.cn (M. Wang); luhuajiang@qust.edu.cn (L. Jiang)

Abstract

Mg–CO₂ battery as a promising strategy for CO₂ conversion and utilization is challenging, owing to the sluggish kinetics of CO₂ reduction reaction (CO₂RR) and the waste of sacrificial Mg anode. Herein, by elaborately designing a highly selective Ni NPs/Ni-N-C SACs electrocatalyst towards CO₂RR and rationally optimizing the electrolyte, an effective aqueous-phase Mg–CO₂ battery is demonstrated to generate not only electricity, but also syngas with CO from the CO₂RR and H₂ from the chemical oxidation of Mg, together higher-valued MgHPO₄ phosphate. Notably, the output of electricity, the proportion of CO/H₂ in syngas, and the yields/crystalline quality of MgHPO₄ can be well regulated by manipulating the operation parameters. The Mg–CO₂ battery generates a favorable open-circuit voltage of 1.44 V with a peak power density of 2.91 mW cm^-2. Under the optimal condition, the Ni NPs/Ni-N-C SACs catalyst displays both a high FE_CO of 98.12% at –0.573 V_RHE and a high CO₂-to-CO current of –20.73 mA cm^-2 at –0.973 V_RHE, owing to the synergistic effect between Ni particles and Ni-N moieties. The proposed Mg–CO₂ battery provides an intriguing approach for CO₂ conversion and utilization in off-grid, with the advantage of co-production of higher-valued chemicals at both electrodes.

https://doi.org/10.1021/acssuschemeng.2c07631