InBi Bimetallic Sites for Efficient Electrochemical Reduction of CO2 to HCOOH.

Formic acid is receiving intensive attention as being one of the most progressive chemical fuels for the electrochemical reduction of carbon dioxide. However, the majority of catalysts suffer from low current density and Faraday efficiency. To this end, an efficient catalyst of In/Bi-750 with InOx nanodots load is prepared on a two-dimensional nanoflake Bi2 O2 CO3 substrate, which increases the adsorption of * CO2 due to the synergistic interaction between the bimetals and the exposure of sufficient active sites. In the H-type electrolytic cell, the formate Faraday efficiency (FE) reaches 97.17% at -1.0 V (vs reversible hydrogen electrode (RHE)) with no significant decay over 48 h. A formate Faraday efficiency of 90.83% is also obtained in the flow cell at a higher current density of 200 mA cm-2 . Both in-situ Fourier transform infrared spectroscopy (FT-IR) and theoretical calculations show that the BiIn bimetallic site can deliver superior binding energy to the * OCHO intermediate, thereby fundamentally accelerating the conversion of CO2 to HCOOH. Furthermore, assembled Zn-CO2 cell exhibits a maximum power of 6.97 mW cm-1 and a stability of 60 h.

Metal-Organic Framework-Derived BiIn Bimetallic Oxide Nanoparticles Embedded in Carbon Networks for Efficient Electrochemical Reduction of CO2 to Formate.

Bismuth-based catalysts exhibit excellent activity and selectivity for the electroreduction of carbon dioxide (CO2). However, single-component bismuth-based catalysts are not satisfactory for the electrochemical reduction of CO2 to formic acid, mainly due to their high hydrogen production, low electrical conductivity, and small catalytic current density. Herein, we used a coordination strategy to recombine Bi and In at the molecular level to form Bi/In bimetallic metal-organic frameworks (MOFs), which were then calcined to obtain MOF-derived Bi/In bimetallic oxide nanoparticles embedded in carbon networks. Thanks to the synergistic effect of bimetallic components, high specific surface area, suitable pore size distribution, and high electrical conductivity of the carbon network, the material exhibits excellent activity and selectivity for electroreduction of CO2 to formate. In H-type electrolyzers, the formate Faradaic efficiency reaches 91% at -0.9 V (vs RHE) and does not decrease significantly within 48 h. In situ Fourier transform infrared spectroscopy confirms the reaction intermediates and reveals that CO2 electroreduction is dominant by the *OCHO pathway.