Inhibiting Sulfur Dissolution and Enhancing Activity of SnS for CO2 Electroreduction via Electronic State Modulation

Heteroatom doping can facilitate intrinsic activity via the tuning of electronic states. However, it is still rare to elucidate the role of a specific metal sulfide electronic state and simultaneously enhance the CO2 electroreduction reaction (CO2RR) stability. SnS is well-known for its ability to produce HCOOH; however, its long-term operational stability is limited by sulfur dissolution. Herein, we propose a strategy to reinforce the S atoms via heteroatom (In) doping. In situ Raman tests and theoretical calculations demonstrate that In atoms with fewer valence electrons (compared with Sn) can tune the electronic state of SnS and strengthen the S–metal bond energy. Consequently, sulfur dissolution was inhibited, and the reaction pathway was optimized. Further, the In-SnS/C achieves a Faradaic efficiency of 96.6% for formate at −0.6 V vs RHE and a catalyst stability of 50 h at a current density of ∼37 mA cm–2. This study shows that altering the electronic structure of SnS via heteroatoms is a strategy to optimize both the activity and stability of electrocatalysts for the CO2RR.