Highly Selective Reduction of CO₂ to Formate at Low Overpotentials Achieved by a Mesoporous Tin Oxide Electrocatalyst

Abstract

A well-ordered mesoporous SnO2 prepared by a simple and inexpensive nanocasting method was used as catalysts for the electrochemical reduction of CO2 to formate. The as-prepared catalyst exhibited high activity toward CO2 reduction, which was capable of reducing CO2 to formate with 38% of Faradaic efficiency (FE) at an applied overpotential as low as 325 mV. The maximum FE for formate generation (75%) was achieved at an applied potential of −1.15 V (vs RHE), accompanied by a high current density of 10.8 mA cm–2. The enhanced catalytic activity obtained with the mesoporous SnO2 electrocatalyst is attributed to its high oxygen vacancy defects (promotes CO2 adsorption and lowers overpotential) and crystallinity that provides sufficient active sites for CO2RR as well as its distinctive structural configurations which reduces impedance to facilitate faster CO2RR reaction kinetics.

A Disquisition on the Active Sites of Heterogeneous Catalysts for Electrochemical Reduction of CO2 to Value‐Added Chemicals and Fuel

“…Similar facet dependent DFT results with Sn, In and Bi catalysts were used as theoretical evidence to justify the catalytic activity of these catalysts for CO 2 RR . In addition, SnO 2 (110) is reported to play a positive role in dictating formate generation during CO 2 RR with a number of literatures with SnO 2 nanoparticle catalysts ascribing the importance of this facet …”

Modulating Activity through Defect Engineering of Tin Oxides for Electrochemical CO2 Reduction

“…[39] It can be observed from Figure 4a, the intensity ratio between defects and the resonant A 1g phonon (I defect /I A1g ) was maximized for FSP-SnO 2 -5 (I defect /I A1g = 1.36) followed by FSP-SnO 2 -7 (I defect /I A1g = 1.25) and the lowest was for FSP-SnO 2 -3 (I defect /I A1g = 1.02). [44] It has been reported that OHC sites, alongside the radicals, assists in the binding of CO 2 reactants, [25,38,45] as well as active sites to stabilize the formate anion radical intermediate. UV-vis carried out with FSP-SnO 2 -5 further indicated that these defects are not changing the electronic states of the catalyst ( Figure S11, Supporting Information).…”

“…Thus, research has focused on the quest to make scalable active catalysts by developing novel nanostructures that can promote mass transport, present higher electrical conductivity as well as contain more active sites. [23,24] While oxygen vacancy defects were ascribed as beneficial for CO 2 RR to formate in prior reports, [23,25] to the best of our knowledge there exists no systematic investigation tuning these vacancies and associating the nature of such defects as well as correlation with CO 2 RR. [16][17][18][19][20] As such, it is becoming imperative to develop designer SnO 2 catalysts using scalable methods that would allow control over tuning the active sites for CO 2 RR.…”

Binary Pd−Ni Nanoalloy Particles over Carbon Support with Superior Alkaline Formate Fuel Electrooxidation Performance

“…In this manuscript, we demonstrate, for the first time, a class of binary PdÀ Ni alloy nanoparticles over two different carbon supports showing exceptional enhancement of the formate oxidation reaction (FOR) performance in alkaline medium, compared to Pd/C. [9][10][11] Formate is further advantageous in terms of its nontoxic and environmentally friendly nature. The more active Pd catalytic sites of the nanoalloy helped to yield mass activities as high as 4.5 A mg À 1 Pd and 7.8 A mg À 1 Pd during FOR.…”

“…[1][2][3][4][5] With alkaline-type direct liquid fuel cells being given greater attention than acid-type fuel cells, [6][7] formate is an ideal fuel alternative to ethanol and methanol. [9][10][11] Formate is further advantageous in terms of its nontoxic and environmentally friendly nature. [9][10][11] Formate is further advantageous in terms of its nontoxic and environmentally friendly nature.…”