Breakthrough in Developing Electrocatalysts for CO2 Reduction through Elemental Doping

Recently, the research group of Prof. Jie Zeng has made a breakthrough in the preparation of formate and CO from electrochemical reduction of CO₂ by using Ni doped SnS₂ nanosheets with different doping contents as electrocatalysts. SnS₂ nanosheets with appropriate Ni content were shown to possess enhanced activity and selectivity toward CO₂ electrochemical reduction. This work was published on Angew. Chem. Int. Ed (Angew. Chem. Int. Ed. 2018, 57, 10954-10958) entitled as “Nickel Doping in Atomically Thin Tin Disulfide Nanosheets Enables Highly Efficient CO₂ Reduction”. Graduate students An Zhang, Rong He, and Huiping Li were the co-first authors of this work.

In CO₂ electroreduction, the critical bottleneck lies in the activation of CO₂ into a radical anion (CO₂^•-) which requires a high reduction potential of -1.9 V vs NHE. Generally, the CO₂ activation concerns an electron transfer from catalysts to a CO₂ molecule, which was closely associated with the electronic structure of catalysts. A powerful method to tailor the electronic structure of catalysts is elemental doping, because the introduction of heteroatoms leads to the hybridization of energy levels between dopants and pristine catalysts. Therefore, elemental doping provided a promising opportunity to facilitate CO₂ activation and thereby improve the performance of CO₂ electroreduction by modifying the electronic structure of catalysts.

The mapping spectra of Ni doped SnS₂ nanosheets and the electrochemical performances for CO₂ reduction.

Herein, we modified atomically thin SnS₂ nanosheets with Ni doping for enhanced performance towards CO₂ electroreduction. The Ni doped SnS₂ nanosheets exhibited higher current density and Faradaic efficiency (FE) for carbonaceous product than those of the pristine SnS₂ nanosheets. When the Ni content was 5 atm %, the Ni doped SnS₂ nanosheets achieved a remarkable FE of 93% for carbonaceous product with a current density of 19.6 mA cm^-2 at -0.9 V vs RHE. During the potentiostatic test, the Ni doped SnS₂ nanosheets remained a steady FE for carbonaceous product without obvious decay of current density. Mechanistic study revealed that Ni doping generated a defect level at conduction band edge and decreased the work function of SnS₂ nanosheets, which benefited the activation of CO₂ and accordingly improved the catalytic performance in CO₂ electroreduction.

This work was supported by CAS, MOST of China, and National Natural Science Foundation of China.