Enhanced catalytic activity and stability of bismuth nanosheets decorated by 3-aminopropyltriethoxysilane for efficient electrochemical reduction of CO2

[Display omitted] •High quality Bi nanosheets (NS) are in-situ prepared on carbon paper by electro reduction.•3-Aminopropyltriethoxysilane (APTES)/Bi-NS highly efficient for CO2 conversion to HCOOH.•APTES/Bi-NS beneficial to formation of intermediates *OCHO to formate.•DFT calculation proves the decrease in energy barrier of OCHO*to HCOOH over APTES/Bi-NS. Herein, the effects of the introduction of 3-aminopropyltriethoxysilane (APTES) on the intrinsic properties of functionalized Bi nanosheets (Bi-NHS) electrocatalyst and the electrocatalytic performance of CO2 reduction reaction were carefully studied. As a result, high selectivities (> 90 %) to formate in significantly wide potentials of 500 mV and the energy efficiency ΦHCOOH as high as 65.8 % at –0.66 V for the cathodic half reaction can be observed. In addition, the Bi-NHS electrode shows a maximal faradic efficiency of 96.0 % at –0.96 V and a low overpotential around 340 mV, maintains well-preserved catalytic activity, giving formate yield of 8.02 g L−1, in a long term of continuous electrolysis. Based on experiment and density functional theory (DFT) calculations, CO2 reduction to formate on Bi(001)-NHS surface is more energetically favorable than that on bare Bi(001) surface and the APTES is excellent ligands as promoters for stabilized catalytic performance of metallic bismuth.