Fig. 5: Mechanism investigations.
From: Acidic CO2-to-HCOOH electrolysis with industrial-level current on phase engineered tin sulfide
a In situ ATR-FTIR spectra of Sn(S)-H. b FTIR peak areas of Sn(S)-H and Sn(S)-H. c Surface Pourbaix diagram of π-SnS (110) and α-SnS (110). The atomic structure (top view) of the S-terminated, stoichiometric and Sn-terminated surface is shown as insets. Cyan sphere: Sn; yellow sphere: S. The working condition of U = −1.1 V (vs. SHE) and pH = 3 is approximately marked in black dashed box. d Adsorption free energy (Gad) of *OCHO, *COOH and *H on Sn (100) and S-doped Sn (100). e Free energy diagram of CO2 electroreduction to HCOOH under U = −1.1 V (vs. SHE) on Sn (100) and S-doped Sn (100). f Differential charge density of Sn (100) (side view) with and without S-doping. The yellow and blue contour represents electron accumulation and depletion, respectively. The isosurface level is set to be 0.02 e/Bohr3. The ball-and-stick model in the lower layer shows the positions of atoms.
