Electroreduction of CO2 to formate with excellent selectivity and stability on nano-dendrite Bi film electrode

Spherical Bi2O3/ATO catalyst with N2 pre-reduction electrocatalytic reduction of CO2 to formic acid

Bi2O3 catalyst with Bi-O bond crystal structure has more active sites, which shows better CO2 catalytic performance than pure Bi catalysts in many catalytic reactions. How to strengthen the Bi-O bond in Bi2O3 to obtain higher selectivity and catalytic activity is a problem worthy of consideration. Here, we develop a N2 pre-reduced spherical Bi2O3/ATO catalyst that has a high formate Faradaic efficiency of 92.7%, which is superior to the existing tin oxide catalyst. Detailed electrocatalytic analysis shows that N2 pre-reduction and spherical structure are helpful for Sn to stabilize the oxidation state of Bi, thus retaining part of the Bi-O structure. The existence of the Bi-O structure can reduce the energy barrier of the CO2 production *OCHO reaction and promote the reaction rate of the CO2-*OCHO-HCOOH path, thus promoting the formation of formate.

Dealloying-derived nanoporous Sn-doped copper with prior selectivity toward formate for CO2 electrochemical reduction

We report nanoporous Cu-Sn catalysts fabricated by chemically dealloying rapid solidified Al-Cu-Sn alloys for the CO2RR. The np-Cu11Sn1 catalyst exhibits a three-dimensional interconnected ligament-channel network structure, which can efficiently convert CO2 to formate with a Faradaic efficiency (FE) of 72.1% at -1.0 V (vs. RHE).

Bi2S3 nanorods grown on multiwalled carbon nanotubes as highly active catalysts for CO2 electroreduction to formate

Bi-based materials are promising electrocatalysts for CO₂ reduction but one of the key technological hurdles is the design of stable, active and affordable Bi-based catalysts over a wide potential range. Herein, Bi₂S₃/CNTs nanocomposites are constructed by anchoring bismuth sulfide (Bi₂S₃) nanorods onto the multiwalled carbon nanotubes (CNTs) and utilizing them in electrocatalytic CO₂ reduction. CNTs, as a support, not only guarantee the conductivity and dispersibility of Bi₂S₃ nanorods but also improve the electrolyte infiltration and optimize the electronic structure of the Bi₂S₃. As expected, the Bi₂S₃/CNTs nanocomposite exhibits a faradaic efficiency for HCOO^- (FE_HCOO-) of 99.3% with a current density of -20.3 mA cm^-2 at -0.91 V vs. RHE. The FE_HCOO- is stably maintained at over > 91% in a wide potential window from -0.71 V to -1.31 V. Theoretical calculation analyses reveal that the strong interaction between Bi₂S₃ and CNTs is conductive to decreasing the energy barrier of *OCHO, stabilizing the intermediate *OCHO, and inhibiting the hydrogen evolution reaction. The current study provides an insightful understanding of the mechanism of the CO₂ electroreduction reaction, and paves a new way for developing superior and affordable electrocatalysts.

Room Temperature Nanographene Production via CO2 Electrochemical Reduction on the Electrodeposited Bi on Sn Substrate

Electrochemical reduction of carbon dioxide (CO₂RR) to crystalline solid carbon at room temperature is challenging, but it is a providential CO₂ utilization route due to its indefinite storage and potential applications of its products in many advanced technologies. Here, room-temperature synthesis of polycrystalline nanographene was achieved by CO₂RR over the electrodeposited Bi on Sn substrate prepared with various bismuth concentrations (0.01 M, 0.05 M, and 0.1 M). The solid carbon products were solely produced on all the prepared electrodes at the applied potential -1.1 V vs. Ag/AgCl and were characterized as polycrystalline nanographene with an average domain size of ca. 3-4 nm. The morphology of the electrodeposited Bi/Sn electrocatalysts did not have much effect on the final structure of the solid carbon products formed but rather affected the CO₂ electroreduction activity. The optimized negative potential for the formation of nanographene products on the 0.05Bi/Sn was ca. -1.5 V vs. Ag/AgCl. Increasing the negative value of the applied potential accelerated the agglomeration of the highly reactive nascent Bi clusters in situ formed under the reaction conditions, which, as a consequence, resulted in a slight deviation of the product selectivity toward gaseous CO and H₂ evolution reaction. The Bi-graphene composites produced by this method show high potential as an additive for working electrode modification in electrochemical sensor-related applications.