Beyond Leverage in Activity and Stability toward CO₂ Electroreduction to Formate over a Bismuth Catalyst

Abstract

The direct production of formate from CO 2 over Bi-based catalysts offers a promising route for producing important chemicals using renewable electricity. Nevertheless, limited by the unstable structure and states of catalysts under electrochemical conditions, electroreduction of CO 2 to formate is still facing a trade-off between activity and stability, especially at high current densities. Herein, we reported a metal−carbon interfacial modulation strategy to synthesize the cross-linked and defective carbon-modified Bi nanoparticle (Bi-DC) catalyst with a stable spatial structure and a unique CO 2 -philic and hydrophobic interface. As a result, the Bi-DC featured a remarkable ability for CO 2 electroreduction to formate in a near neutral electrolyte (1 M KHCO 3 ) and was even comparable to the CO 2 -to-formate activity in the strongly basic systems, along with a high partial current density and formation rate for formate of −378 mA cm −2 and 7 mmol cm −2 h −1 , respectively. Also, it achieved a stable electrolysis for 120 h at 0.4 A in a membrane electrode assembly reactor and even operated stably at an industrial large current of 5 A. The carbon species promoted the reconstruction and dispersion of active component Bi, together with a spatial confinement effect that facilitated the formation of formate and achieved stable long-term electrolysis.

Porous Bi Nanosheets Derived from β-Bi2O3 for Efficient Electrocatalytic CO2 Reduction to Formate

“…At present, it has been proposed that IIB, IIIA, IVA, and VA group metals, such as Pb, Bi, Cd, Hg, In, and Sn can reduce CO 2 to HCOOH. ,− However, because Pb, Cd, Hg, and other metals are expensive and harmful to the environment, they are not suitable as catalysts for the CO 2 RR in practical applications. To meet the urgent need for environmentally benign and earth abundant metal-based catalysts, bismuth-based materials are often explored for the production of formate in CO 2 RR due to their advantages of low cost, low toxicity, high selectivity, and good activity. ,− However, due to the large energy barrier and slow kinetics in the process of transferring one electron to form *CO 2 – intermediate in the electrocatalytic CO 2 reduction reaction, most reported bismuth-based catalysts can only achieve high formate selectivity at specific potentials or within a relatively narrow range of potentials.…”