CeO_x Promoted Electrocatalytic CO₂ Reduction to Formate by Assisting in the Critical Hydrogenation Step

Abstract

Bismuth oxide is one of the best-known formate production catalysts from electrocatalytic reduction of CO2. It came as a surprise here that its hybridization with CeO x drastically boosted the catalytic activity and stability on CO2 reduction toward formate formation. Specifically, the formate faradaic efficiency of Bi2O3–CeO x exceeds 85% starting from −0.3 V vs reversible hydrogen electrode (RHE) and remains above 90% from −0.5 V to −1.1 V vs RHE, outperforming the pure Bi2O3 and most other reported formate catalysts. Experimental and computational results suggest that the significantly enhanced catalytic activity arises from the electronic synergy between Bi2O3 and CeO x . The electronic synergy results in abundant defects in CeO x favorable for CO2 activation and adsorption. Moreover, CeO x promotes water dissociation to form H* but with a large energy barrier to H2, which can easily react with CO2 and accelerate the rate-determining step of hydrogenation step. The generality of the CeO x -promoted catalysis for CO2 reduction to formate is also demonstrated for In2O3. This work opens up a new avenue for the design of efficient CO2RR electrocatalysts.

Rare‐earth Element‐based Electrocatalysts Designed for CO2 Electro‐reduction

“…For instance, Bi 2 O 3 supported CeO x achieves high selectivity toward formate by the electronic synergy between Bi 2 O 3 and CeO x . [91] CeO x promotes water dissociation to form H* but produces a large energy barrier to H 2 , which accelerates the rate-determining step of the hydrogenation step. Valenti et al designed MWCNTs supported CeO 2 NPs (Figure 9e).…”

“…In addition to being used as a support, CeO 2 could also be supported on other materials to boost the catalytic performance of CO 2 RR. For instance, Bi 2 O 3 supported CeO x achieves high selectivity toward formate by the electronic synergy between Bi 2 O 3 and CeO x [91] . CeO x promotes water dissociation to form H* but produces a large energy barrier to H 2 , which accelerates the rate‐determining step of the hydrogenation step.…”

Rare earth oxide based electrocatalysts: synthesis, properties and applications

“…Specifically, the FEs of Bi 2 O 3 -CeO x in formic acid exceed 85% at À0.3 V vs. RHE and remain above 90% at À0.5 V to À1.1 V vs. RHE, surpassing pure Bi 2 O 3 and most other formic acid catalysts. 305 The experimental and computational results indicate that the electronic synergistic effect between Bi 2 O 3 and CeO x significantly enhances the catalytic activity. The synergistic effect of electrons leads to a large number of defects in CeO x that are conducive to CO 2 activation and adsorption.…”

Strong Electron Coupling Effect at the CoO/CeO2 Interface Enables Efficient Oxygen Evolution Reaction

“…Therefore, a large range of nonprecious metal-based electrocatalysts have also been studied to find out whose OER performance can be comparable to that of IrO 2 /RuO 2 , especially the first transition elements represented by oxides or hydroxides of Fe/Co/Ni. − Due to the special properties of cerium oxide, CeO 2 plays an important role in improving the OER performance of transition metals-based catalysts whether as a hybrid, substrate, or interface. The easy valence shift between Ce 3+ and Ce 4+ in CeO 2 can act to (1) optimize the electronic structures and coordination environments of transition metals to obtain high intrinsic activity, (2) promote charge transfer and electron conduction, and (3) bring in abundant oxygen vacancies as the OER active sites. ,,− …”