Boosting Production of HCOOH from CO₂ Electroreduction via Bi/CeO_x

Abstract

Formic acid (HCOOH) is one of the most promising chemical fuels that can be produced through CO 2 electroreduction. However, most of the catalysts for CO 2 electroreduction to HCOOH in aqueous solution often suffer from low current density and limited production rate. Herein, we provide a bismuth/cerium oxide (Bi/CeO x) catalyst, which exhibits not only high current density (149 mA cm À2), but also unprecedented production rate (2600 mmol h À1 cm À2) with high Faradaic efficiency (FE, 92 %) for HCOOH generation in aqueous media. Furthermore, Bi/CeO x also shows favorable stability over 34 h. We hope this work could offer an attractive and promising strategy to develop efficient catalysts for CO 2 electroreduction with superior activity and desirable stability. Excessive CO 2 emission has brought about severe problems related to resources, environment, and climate. Thus, converting CO 2 into valuable chemical fuels attract more and more research attention. [1] Among the various conversion approaches, electrochemical reduction of CO 2 in aqueous media is more favorable because it can make better use of electricity generated from sustainable sources without producing any additional CO 2. [1-5] Nevertheless, low activity, selectivity and stability of catalysts are still the big challenges for CO 2 electroreduction. Therefore, developing efficient electrocatalysts for CO 2 reduction is highly desired. As one of the most attractive CO 2 reduction products, formic acid (HCOOH) is widely identified as a desirable hydrogen carrier. [6-10] Up to now, many metallic catalysts, including Cd, Hg, Pd, Pb, In, Sn and Bi are found to be effective to form HCOOH (or formate) through CO 2 electroreduction. [11-29] However, the activities are still very low even using the toxic or noble metals. As well as we know, the current density and production rate (in H-type reaction cell) by far are less than 80 mA cm À2 , and 1500 mmol h À1 cm À2 , respectively. [11-29] On the other side, high applied potentials and current density always lead to the low Faradaic efficiency (FE) due to the severe competitive hydrogen evolution reaction (HER). [25] Therefore, achieving a low-cost, eco

Tunable product selectivity on demand: a mechanism-guided Lewis acid co-catalyst for CO2 electroreduction to ethylene glycol

“…Fundamental advances in electrocatalysts, 3 electrolytes 4 and electrochemical cell designs, 5 have propelled AP technologies to a point where scale-up of electrolysis is beginning to occur for generating simple C 1 products such as carbon monoxide, 6,7 syngas, 8,9 and formate/formic acid [10][11][12][13][14][15] with relatively high selectivity and reaction rates. Distinct classes of CO 2 RR electrocatalysts have been found that discriminate between the formate and carbon monoxide pathways, 1,16,25 thereby allowing C 1 product selectivity and suppressing self-poisoning by CO.…”

Activating Bi p‐orbitals in Dispersed Clusters of Amorphous BiOx for Electrocatalytic Nitrogen Reduction

“…With half‐filled p ‐orbitals, the elements of the VA group are of special interest [16, 17] . While various oxidation states are known for N ( 2s 2 2p 3 ), the first element of the VA group, [18–20] the reported oxidation states for Bi ( 6s 2 6p 3 ), the last element of the VA group, are mainly 0 and +3 [21–23] . Modulation of the p ‐orbital energies for Bi has been scarcely investigated, also making the identification of the active phase of Bi during catalysis quite difficult [24] …”

“…[16,17] While various oxidation states are known for N (2s 2 2p 3 ), the first element of the VA group, [18][19][20] the reported oxidation states for Bi (6s 2 6p 3 ), the last element of the VA group, are mainly 0 and + 3. [21][22][23] Modulation of the p-orbital energies for Bi has been scarcely investigated, also making the identification of the active phase of Bi during catalysis quite difficult. [24] With ultra-low proton and electron affinities, the N 2 molecule is known to be chemically inert under a wide range of conditions and, accordingly, difficult to be activated by most transition metal (d-orbital) catalysts.…”

CeO2 Promotes CO2 Electroreduction to Formate on Bi2S3 via Tuning of the *OCHO Intermediate

“…However, the effect of CeO X on the electronic structure has not been debated in detail. Recent studies revealed that the introduction of CeO 2 can prevent Cu 2+ from being reduced to strengthen the adsorption of CO* on catalysts, thus promoting the efficient production of CH 4 . However, although the role of CeO 2 in CO 2 reduction reaction has been investigated in numerous studies, the correlation between the adsorption of the key intermediate with the electronic structure and dynamic structural evolution of ceria-incorporated sulfide materials has not been systemically explored.…”

“…Recent studies revealed that the introduction of CeO 2 can prevent Cu 2+ from being reduced to strengthen the adsorption of CO* on catalysts, thus promoting the efficient production of CH 4 . 22 However, although the role of CeO incorporated sulfide materials has not been systemically explored.…”