Nanostructure Engineering of Sn‐Based Catalysts for Efficient Electrochemical CO₂ Reduction

Abstract

safe limit 350 ppm), [7] which increased to 414 ppm in 2020, [3,8] with an annual growth rate of ≈1.57 ppm. This value will probably reach 570 ppm by 2100 without proper regulation. [9] Such high concentration of CO 2 in the atmosphere have triggered a series of ecological and environmental issues, including climate change, glacier melting, and sea levels rising, [7,8,10,11] which threaten the sustainable development of humans. Significant endeavors have been devoted to impede the increase of CO 2 concentration, which includes the exploitation of renewable green energy to alleviate the dependence on fossil fuels, [7,12,13] CO 2 sequestration, [14] and mimicking the natural photosynthesis process by converting CO 2 and H 2 O into valuable chemical products to close the carbon cycle. [15,16] Artificial photosynthesis in particular has attracted considerable research interest over the past few decades, since it offers the possibility of producing chemical products that traditionally rely on fossil fuels using waste CO 2 . [15,17] Various technologies have been implemented in artificial photosynthesis process, such as biocatalysis, [18,19] thermocatalysis, [20,21] photocatalysis, [22][23][24][25][26] electrocatalysis, [27][28][29] as well as photoelectrocatalysis. [30] Electrochemical CO 2 reduction (ECO 2 R) has attracted considerable attention due to its unique advantages, which include the relatively mild operating conditions; the tunable product selectivity and reaction path by regulating reaction Excessive anthropogenic CO 2 emission has caused a series of ecological and environmental issues, which threatens mankind's sustainable development. Mimicking the natural photosynthesis process (i.e., artificial photosynthesis) by electrochemically converting CO 2 into value-added products is a promising way to alleviate CO 2 emission and relieve the dependence on fossil fuels. Recently, Sn-based catalysts have attracted increasing research attentions due to the merits of low price, abundance, non-toxicity, and environmental benignancy. In this review, the paradigm of nanostructure engineering for efficient electrochemical CO 2 reduction (ECO 2 R) on Sn-based catalysts is systematically summarized. First, the nanostructure engineering of size, composition, atomic structure, morphology, defect, surficial modification, catalyst/ substrate interface, and single-atom structure, are systematically discussed. The influence of nanostructure engineering on the electronic structure and adsorption property of intermediates, as well as the performance of Sn-based catalysts for ECO 2 R are highlighted. Second, the potential chemical state changes and the role of surface hydroxides on Sn-based catalysts during ECO 2 R are introduced. Third, the challenges and opportunities of Sn-based catalysts for ECO 2 R are proposed. It is expected that this review inspires the further development of highly efficient Sn-based catalysts, meanwhile offer protocols for the investigation of Sn-based catalysts.

Electrocatalytic Performance of Interconnected Self‐Standing Tin Nanowire Network Produced by AAO Template Method for Electrochemical CO2 Reduction**

“…The results of XPS studies conducted on the tin before and after CO 2 reduction gave similar outcomes; they all showed that SnO structures became the dominant phase after reduction [61,62] . Further, in‐situ and operando analyses have also proved that tin oxide and metallic tin co‐exist (SnO x /Sn) on the surface of the tin‐based electrocatalysts during reduction rather than the metallic tin (Sn 0 ) [6,35,50,55–57,61–66] . Based on the mentioned studies and the obtained Raman analysis in this work, the improved formate selectivity over An−Sn NW electrodes results from the mixed oxide structure, the main catalytic layer for CO 2 reduction.…”

“…In addition, we have also anodically oxidized the tin nanowires to benefit from improved catalytic performance [41] and increased surface area [42–46] . Compared to other studies in the literature on tin‐based nanowires, [25,26,34,35] our work put a difference by introducing the production of the catalyst via the AAO template followed by anodic oxidation. Moreover, our electrocatalyst does not require to be deposited on any substrate (carbon paper, GDL, etc.).…”

Bimetallic In–Sn Core–Shell Catalyst Enabling Highly Efficient Electrocatalytic CO2 Reduction to Formate

“…Electrochemical CO 2 reduction reaction (CO 2 RR) is regarded as a sustainable and safe technology that combines CO 2 capture and direct conversion to produce low-carbon chemicals and fuels. − Recent techno-economic analysis manifests that formate, among the various CO 2 RR products, is practically viable and commercially profitable in industrial applications owing to the relatively low activation potential needs. , It has been demonstrated that various metals and their derivatives could convert CO 2 into formate which could be readily incorporated to produce value-added chemicals. ,− For instance, Sn-based materials are attractive catalysts for the CO 2 RR to formate in terms of their earth-abundant merits. − Unfortunately, it remains challenging to realize high selectivity owing to the inappropriate binding energy with intermediates and severe hydrogen evolution reaction (HER) . Furthermore, the poor electrical conductivity of monometallic Sn-based materials leads to undesirable electrocatalytic activity. , …”

Decrypting the Electron‐Withdrawing Effect of Au‐Decorated Bi2O3 for Efficient CO2‐to‐Formate Electroreduction

“…As formate is a kind of important industrial feedstock and hydrogen carrier in energy industry, it is considered as one of the promising products in the eCO 2 RR process. [5][6][7][8] Hereby, it is urgent to develop more high performance electrocatalyst to boost the CO 2 -to-formate reduction. Heretofore, metal-based catalysts (such as Bi, [9][10][11][12] Sn, [13][14][15] In, [16][17][18] Pb, [19,20] and Pd, [21][22][23] ) present excellent formate selectivity in the eCO 2 RR process.…”