Bi₂O₃/BiO₂ Nanoheterojunction for Highly Efficient Electrocatalytic CO₂ Reduction to Formate

Abstract

Heterostructure engineering plays a vital role in regulating the material interface, thus boosting the electron transportation pathway in advanced catalysis. Herein, a novel Bi2O3/BiO2 heterojunction catalyst was synthesized via a molten alkali-assisted dealumination strategy and exhibited rich structural dynamics for an electrocatalytic CO2 reduction reaction (ECO2RR). By coupling in situ X-ray diffraction and Raman spectroscopy measurements, we found that the as-synthesized Bi2O3/BiO2 heterostructure can be transformed into a novel Bi/BiO2 Mott–Schottky heterostructure, leading to enhanced adsorption performance for CO2 and *OCHO intermediates. Consequently, high selectivity toward formate larger than 95% was rendered in a wide potential window along with an optimum partial current density of −111.42 mA cm–2 that benchmarked with the state-of-the-art Bi-based ECO2RR catalysts. This work reports the construction and fruitful structural dynamic insights of a novel heterojunction electrocatalyst for ECO2RR, which paves the way for the rational design of efficient heterojunction electrocatalysts for ECO2RR and beyond.

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

“…The peak at 1430 cm –1 is attributed to the symmetric stretching mode of OCO in the *OCHO species of the dioxygen bridge, which is present in the adsorbed *OHCO and HCOOH, and the product signal gradually increases with increasing voltage. Meanwhile, the peak of *OCHO at 1593 cm –1 is enhanced with increasing voltage, indicating an increase in the content of *OHCO and HCOOH. ,, In an attempt to study and confirm the reaction process in more depth, we subjected the catalyst to electrolysis at −0.9 V (vs RHE) for 1 h at different periods and monitored it using in situ FT-IR spectroscopy (Figure b). Compared with the spectra at different voltages, the spectra at different periods show the changes in the content of each group during the reaction more clearly.…”

The Critical Role of Initial/Operando Oxygen Loading in General Bismuth-Based Catalysts for Electroreduction of Carbon Dioxide

“…In summary, the multiple characterizations indicate that the metalloid intermediate states probably exist in all Bi-based catalysts, while the in situ oxygen level in such intermediate, which also demonstrates a strong correlation to the initial lattice oxygen and/or valence state of Bi, presumably plays a crucial role in the overall CO 2 RR performance. Based on this hypothesis, we further surveyed a number of Bi-based catalysts as reported in recent literatures. ,,− As summarized in Figure , an obvious correlation is indeed observed between the Bi valence state in the as-prepared catalytic materials and the reported FE HCOOH in carbon dioxide reduction. Interestingly, the 2D metallic bismuthene also shows the highest-level performance, which could be rationalized by the strong surface adsorption of anion and oxygens (presumably from the inevitable oxidation of 2D structure with high surface energy), leading to an actual high oxidation level on the bismuth surface.…”

CO2 Conversion at High Current Densities: Stabilization of Bi(III)-Containing Electrocatalysts under CO2 Gas Flow Conditions

“…Since the pioneering work by Hori et al, it has been known that particular oxophilic materials, e.g., Sn, − Pb, Cd, Tl, and In, favor CO 2 RR pathways toward formate production. However, debate continues regarding the mechanistic role of the respective metal oxides, which are either formed in situ during electrolysis or applied directly as the catalyst (precursor). − Advanced operando techniques, e.g., vibrational ,− and X-ray absorption spectroscopy, − have been successfully employed to gain deeper mechanistic insight into the electrolysis time, current density, and potential-dependent activation of CO 2 RR catalysts under operating conditions. , A recent example is based on the use of oxidic bismuth electrocatalysts, ,, which had already demonstrated superior selectivities toward formate production in classical H-type cell testing environments, with Faradaic efficiencies (FEs) exceeding 95% within an extraordinarily (approximately 1.1 V) , wide potential window. For a CO 2 -saturated 0.5 mol dm –3 KHCO 3 electrolyte solution, a combination of electrochemical analysis and operando Raman spectroscopy during CO 2 RR revealed the coupling of two potential-dependent CO 2 RR pathways as the origin of this superior catalytic performance .…”