1D SnO₂ with Wire‐in‐Tube Architectures for Highly Selective Electrochemical Reduction of CO₂ to C₁ Products

Abstract

Electrochemical reduction of CO2 (ERC) into useful products, such as formic acid and carbon monoxide, is a fascinating approach for CO2 fixation as well as energy storage. Sn‐based materials are attractive catalysts for highly selective ERC into C1 products (including HCOOH and CO), but still suffer from high overpotential, low current density, and poor stability. Here, One‐dimensional (1D) SnO2 with wire‐in‐tube (WIT) structure is synthesized and shows superior selectivity for C1 products. Using the WIT SnO2 as the ERC catalyst, very high Faradaic efficiency of C1 products (>90%) can be achieved at a wide potential range from −0.89 to −1.29 V versus RHE, thus substantially suppressing the hydrogen evolution reaction. The electrocatalyst also exhibits excellent long‐term stability. The improved catalytic activity of the WIT SnO2 over the commercial SnO2 nanoparticle indicates that higher surface area and large number of grain boundaries can effectively enhance the ERC activity. Synthesized via a facile and low‐cost electrospinning technology, the reduced WIT SnO2 can serve as a promising electrocatalyst for efficient CO2 to C1 products conversion.

Efficient Electrochemical Reduction of CO2 to HCOOH over Sub‐2 nm SnO2 Quantum Wires with Exposed Grain Boundaries

“…Thekinetic analysis further supports the fact that the exposed GBs on the ultrathin 1D SnO 2 QWs can tailor the binding energies of reaction intermediates,a nd consequently lead to the enhanced CO 2 RR performance. Thep eaks located at 495.5 and 487.2 eV in the Sn 3d XPS spectra of the ultrathin SnO 2 QWs and SnO 2 NPs match well with the characteristic peaks assigned to Sn 3d 3/2 and Sn 3d 5/2 ionization states, [22] which clearly confirms the formation of Sn IV O 2 .M oreover,n egligible shifts are observed on the spectra of the ultrathin SnO 2 QWs as compared to those of SnO 2 NPs,a ni ndication of ignorable effect of the exposed GBs on the binding energies of Sn 3d. Thesurface electronic states of the ultrathin SnO 2 QWs and SnO 2 NPs were first studied by X-ray photoelectron spectroscopy (XPS), as shown in Figure 4b (see also the Supporting Information, Figure S15).…”

“…Theu ltrathin SnO 2 QWs possess as maller ECSA (C dl = 5.7 mF cm À2 )than SnO 2 NPs (C dl = 7.1 mF cm À2 ), which is perhaps due to the interconnections of SnO 2 QDs.T hat implies that the circa 1.4-fold higher specific catalytic activity of SnO 2 QWs should originate from the presence of intrinsically more active sites associated with the exposed GBs on the surface.T his evidently confirms the GB-enhanced effect on materials with extremely small dimension. [22][23][24] However,the ultrathin SnO 2 QWs are extremely selective for HCOOH formation (FE of ca. To discriminate the preferred occurrence of CO 2 RR rather than HER, the products were further characterized after electrolyzing at various potentials (Supporting Information, Figure S8), among which the liquid and gaseous products were quantitatively measured using high-performance liquid chromatography (HPLC) and online gas chromatography (GC), respectively.…”

“…[10] Furthermore,H COOH has emerged as an alternative feedstock for direct fuel cells. [21][22][23][24] Besides,c omputational studies have suggested that the broken local spatial symmetry adjacent to the grain boundary (GB) can alter the binding energies of reaction intermediates,and consequently accelerate CO 2 RR toward CO formation. [21][22][23][24] Besides,c omputational studies have suggested that the broken local spatial symmetry adjacent to the grain boundary (GB) can alter the binding energies of reaction intermediates,and consequently accelerate CO 2 RR toward CO formation.…”

“…To persuasively clarify the enhanced catalytic activity of the ultrathin SnO 2 QWs for CO 2 RR, identical measurements were also carried out for SnO 2 NPs with an average size of 5.5 nm (Supporting Information, Figure S6) for comparison. [22,24] To rule out the surface area effect owing to the different morphologies of QW and NP,t he electrochemically active [22,24] To rule out the surface area effect owing to the different morphologies of QW and NP,t he electrochemically active …”

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

“…[3][4][5] Despite the development of numerous catalyst materials for CO 2 RR to formate, the large-scale adoption of this technology remains limited by the absence of highperforming inexpensive electrocatalysts that can be produced in bulk and that requires lower energy input. [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. 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.…”