Facile fabrication of porous Sn-based catalysts for electrochemical CO2 reduction to HCOOH and syngas

[Display omitted] •Porous Sn-based catalysts are fabricated by bubble-assisted electrodeposition.•Faradaic efficiency for each products is affected by Sn roughness factor.•Sn0.29In0.71 foam catalyst achieves Faradaic efficiency of 59.2% for HCOOH.•H2/CO ratio in gas product is in a range of 1.6–3.2, which can be used as syngas. Porous Sn and Sn-based binary catalysts are facilely fabricated by an electrodeposition method. Varying conditions for Sn electrodeposition enables a control of Sn roughness, which exhibits a significant effect on catalytic performance for electrochemical CO2 reduction. At a specific applied potential, the porous Sn catalyst with relative roughness factor of 56.5 demonstrates a HCOOH Faradaic efficiency of 40.7% with a H2/CO ratio of 2.2. Further improvement of the HCOOH Faradaic efficiency to 59.2% is achieved by using a porous Sn0.29In0.71 catalyst. This catalyst also achieves a H2/CO ratio of 2.2, which can be used as syngas to produce value-added hydrocarbons.