Ceria -Mediated Dynamic Sn⁰/Sn^δ+ Redox Cycle for CO₂ Electroreduction

Abstract

Electrocatalytic CO 2 reduction has been considered an effective carbon neutrality as well as energy storage strategy integrated with renewable electricity. CO 2 conversion to formate is a feasible route using earth-abundant and nontoxic tin-based catalysts. However, they suffer from degradation and thus decrease in formate selectivity during operation. Guided by density functional theory (DFT) calculations, herein, we synthesized CeO 2 −SnO 2 heterostructures by a facile electrospinning method, which exhibited a maximum formate partial current density of ∼500 mA•cm −2 with 87.1% faradaic efficiency and a long-term stability in a flow cell. Proved by in situ attenuated total reflectance infrared absorption spectroscopy (ATR-IRAS) and Raman spectra as well as post-X-ray photoelectron spectroscopy (XPS) analysis, a dynamic CeO 2 -mediated Sn 0 /Sn δ+ redox cycle mechanism was proposed: oxygen vacancies generated on cerium oxides prompted water dissociation to produce *OH and *H species, where the former oxidize Sn 0 into active Sn δ+ , facilitating the conversion of CO 2 to the key intermediate *OCHO with the help of the latter. This work may provide a general strategy to design stable and efficient catalysts for practical CO 2 electrolyzers.

Stabilizing Undercoordinated Zn Active Sites through Confinement in CeO2 Nanotubes for Efficient Electrochemical CO2 Reduction

“…Accordingly, we propose a CeO 2 nanotube with morphology and chemical strategy to stabilize Zn δ+ sites and enhance the durability of the electrocatalyst. The nanotube with confinement effect could stabilize the Zn δ+ sites, and CeO 2 with the Ce 3+ /Ce 4+ redox could inhibit the electron accumulation around the unsaturated site and thus prevent the reduction degradation of active Zn δ+ sites during CO 2 electrolysis [25–28] . The hollow core–shell structure Zn δ+ /ZnO/CeO 2 with a high selectivity of 76.9 % at −1.08 V vs. RHE toward CO product and the CO selectivity in a long‐term stability test over 18 h. In situ characterization and theoretical studies demonstrate that the energy barrier for the formation of *COOH is thermodynamically reduced by Zn δ+ sites.…”

“…The nanotube with confinement effect could stabilize the Zn δ + sites, and CeO 2 with the Ce 3 + /Ce 4 + redox could inhibit the electron accumulation around the unsaturated site and thus prevent the reduction degradation of active Zn δ + sites during CO 2 electrolysis. [25][26][27][28] The hollow core-shell structure Zn δ + /ZnO/CeO 2 with a high selectivity of 76.9 % at À 1.08 V vs. RHE toward CO product and the CO selectivity in a long-term stability test over 18 h. In situ characterization and theoretical studies demonstrate that the energy barrier for the formation of *COOH is thermodynamically reduced by Zn δ + sites. And the confinement strategy ensures the stability of Zn δ + species, which contributes to maintaining the CO selectivity in a long-term stability.…”

Multiscale CO2 Electrocatalysis to C2+ Products: Reaction Mechanisms, Catalyst Design, and Device Fabrication

“…The C 1 products, CO and HCOOH, are produced with high selectivity under high current densities and provide inspiring commercialization prospects in CO 2 reduction. 7,8 Comparatively, more highly reduced multicarbon products offer higher energy densities and properties that are consistent with existing market demands. 9,10 Current procedures for preparing carbon fuels originate from thermochemical reactions at high temperatures and pressures.…”

“…Successful utilization demands high faradaic efficiencies to give desirable products, stable operation under high current densities, and stabilization for long-term production. The C 1 products, CO and HCOOH, are produced with high selectivity under high current densities and provide inspiring commercialization prospects in CO 2 reduction. , Comparatively, more highly reduced multicarbon products offer higher energy densities and properties that are consistent with existing market demands. , Current procedures for preparing carbon fuels originate from thermochemical reactions at high temperatures and pressures. Replacing these energy-intensive procedures with renewable alternatives, based on electrosynthesis with a variety of energy sources, makes the electrogeneration of C 2+ products an intriguing target …”

Interfacial Electronic Interaction in In2O3/Poly(3,4-ethylenedioxythiophene)-Modified Carbon Heterostructures for Enhanced Electroreduction of CO2 to Formate

“…The carbon dioxide electroreduction reaction (CO 2 RR), converting CO 2 into useful chemicals or fuels, provides an elegant route to establish a sustainable carbon neutral cycle. , Formate, as a product of a two-electron transfer process in CO 2 RR, is one of the most promising products to be prepared on an industrial scale. , So far, Cu-, , Bi-, , Sn-, − Pb-, Pd-, and In-based metal oxide/sulfide/nitride , catalysts have been developed to effectively convert CO 2 to formate. Among them, In-based electrocatalysts for CO 2 RR have attracted much attention due to their excellent CO 2 RR selectivity toward targeted formate (HCOO – ) or formic acid (HCOOH). , However, achieving a high formate selectivity and formate formation rate at an industrial current density (>200 mA cm –2 ) for In-based catalysts remains a big challenge on account of its conductivity limitation and the high energy barriers of CO 2 activation. , Therefore, it is highly necessary to promote electron transfer and reaction intermediate adsorption on the catalysts for perfecting CO 2 RR performance.…”