Selective CO₂ Electroreduction to Formate on Polypyrrole‐Modified Oxygen Vacancy‐Rich Bi₂O₃ Nanosheet Precatalysts by Local Microenvironment Modulation

Abstract

Challenges remain in the development of highly efficient catalysts for selective electrochemical transformation of carbon dioxide (CO2) to high‐valued hydrocarbons. In this study, oxygen vacancy‐rich Bi2O3 nanosheets coated with polypyrrole (Bi2O3@PPy NSs) are designed and synthesized, as precatalysts for selective electrocatalytic CO2reduction to formate. Systematic material characterization demonstrated that Bi2O3@PPy precatalyst can evolve intoBi2O2CO3@PPy nanosheets with rich oxygen vacancies (Bi2O2CO3@PPy NSs) via electrolyte‐mediated conversion and function as the real active catalyst for CO2 reduction reaction electrocatalysis. Coating catalyst with a PPy shell can modulate the interfacial microenvironment of active sites, which work in coordination with rich oxygen vacancies in Bi2O2CO3 and efficiently mediate directional selective CO2 reduction toward formate formation. With the fine‐tuning of interfacial microenvironment, the optimized Bi2O3@PPy‐2 NSs derived Bi2O2CO3@PPy‐2 NSs exhibit a maximum Faradaic efficiency of 95.8% at −0.8 V (versus. reversible hydrogen electrode) for formate production. This work might shed some light on designing advanced catalysts toward selective electrocatalytic CO2 reduction through local microenvironment engineering.

In Situ Dissociated Chalcogenide Anions Regulate the Bi-Catalyst/Electrolyte Interface with Accelerated Surface Reconstruction toward Efficient CO2 Reduction

“…31,32 From the O 1s spectrum (Figure S4c), two peaks at binding energies of 529.4 and 531.0 eV can be observed, which are attributed to the lattice oxygen and absorbed oxygen, respectively. 33 Moreover, the single peak at 224.5 eV confirms the existence of S 2− (Figure S4d). 34 For other as-prepared Bibased catalysts (Figures S5,S6), the Bi 4f and O 1s spectra are consistent with those of Bi 2 O 2 S. Additionally, Se and Cl can be detected for Bi 2 O 2 Se and BiOCl, respectively.…”

“…For Bi 2 O 2 S, the Bi 4f, S 2s, C 1s (as reference), and O 1s are indicated at the survey spectrum in Figure S4a. In Bi 4f spectrum (Figure S4b), the peaks at ∼158.3 and 163.6 eV with a peak split of 5.3 eV is attributed to Bi 3+ . , From the O 1s spectrum (Figure S4c), two peaks at binding energies of 529.4 and 531.0 eV can be observed, which are attributed to the lattice oxygen and absorbed oxygen, respectively . Moreover, the single peak at 224.5 eV confirms the existence of S 2– (Figure S4d).…”

Controlled boron incorporation tuned two-phase interfaces and Lewis acid sites in bismuth nanosheets for driving CO2electroreduction to formate

“…[13][14][15][16][17] In many reports, the high overpotential and competitive hydrogen evolution reaction (HER) of multiple electron transfer pathways are the main reasons for the poor selectivity and low efficiency of electrocatalytic CO 2 RR to formic acid (or formate). [18][19][20][21] Bismuth (Bi) stands out among many metals due to its low cost and environmental friendliness, most importantly, its intrinsic large hydrogen release overpotential and appropriate CO 2 *À moderate adsorption strength. [22][23][24][25] As an important reaction step in the production of targeted products by the CO 2 RR, the adsorption and activation ability of CO 2 molecules largely affect the efficiency of the electrocatalytic CO 2 RR process.…”

Phase Interface Regulating on Amorphous/Crystalline Bismuth Catalyst for Boosted Electrocatalytic CO2 Reduction to Formate

“…15,16 However, the unsatisfied current density and lower formate faradaic efficiency largely hamper their scalable application. 17,18 Among metal-based materials for electrochemical CO 2 reduction into formate, 19,20 Bi-based electrocatalysts have emerged as the most promising candidate. 21,22 In addition to inherent catalytic performance, abundant reserves, and nontoxicity, Bi-based materials also can inhibit the competition of the hydrogen evolution reaction (HER) in the CO 2 reduction process.…”

“…The conversion of carbon dioxide (CO 2 ) into value-added low carbon chemicals and fuels (carbon monoxide, methane, ethylene, etc.) is considered as a sustainable approach to alleviate worldwide CO 2 emission problems. − Compared to gaseous products of CO 2 electrolysis, liquid chemical formic acid (HCOOH) and formate (HCOO – ) have aroused ever-growing interests owing to their high energy density by volume, safe storage, and good integration with the currently existing infrastructure, showing economic and practical applications in synthesis industries and formic acid fuel cells. − Therefore, giant endeavors have been devoted to pursuing low-cost, advanced, and robust electrocatalysts, and much important progress has been achieved. , However, the unsatisfied current density and lower formate faradaic efficiency largely hamper their scalable application. , …”