Electric Double Layer Structure in Electrocatalytic Carbon Dioxide Reduction

Abstract

Environmental degradation and climate change caused by excessive CO2 emissions have become the most serious challenges facing humanity. The electrocatalytic CO2 reduction reaction (CO2RR) is an ideal way to produce high‐value chemicals and solve environmental pollution at the same time. The electric double layer (EDL) structure at the electrochemical interface can greatly influence the local catalytic environment, but it is not fully understood. Herein, recent advances in EDL structure for CO2RR are focused. The main components of the EDL, including adsorbates on the electrode surface, metal/water interface, cations, anions, and differential capacitance are described. The latest experimental and theoretical understanding of EDL and their impact on CO2RR are presented. Finally, the current challenges encountered and the outlook for future development are discussed. This review describes the influence of EDL structure on CO2 reduction, which is of guiding significance for the design of new and efficient CO2 electrocatalysts.

Understanding the Electrode–Electrolyte Interfaces of Ionic Liquids and Deep Eutectic Solvents

“…Consequently, a maximum in capacitance was observed both in negative and positive polarizations, thus forming the peaks on both sides of the PZC minima, likened to the two humps on a camel, hence referred to as the camel-shape. Further, Pajkossy et al 48 observed only a single peak formation (bell-shape) with the more reactive metal Pt (111) electrode immersed in potassium perchlorate (KClO 4 ) and NaF solutions. The authors attributed the peak formation to reorientation of the water dipole layer and chemisorption of the water at the interface.…”

“…The interfacial structure significantly influences the voltage profile and hence the thermodynamics and kinetics of electrochemical reactions (e.g., in energy storage devices, sensors, and electrocatalytic reactors). In particular, a direct connection can be made between the capacitance and the energy storage capacity, eq , in electrical double-layer capacitors, also known as supercapacitors. C = q V C is the capacitance, q is the charge, and V is the voltage applied.…”

Linking Electric Double Layer Formation to Electrocatalytic Activity

“…In these cases, the composition of the electric double layer is key, and we view ionic correlations as important for understanding electrochemical nitrate reduction rates and selectivity. 15,23 For further context into how electric double layer formation under nonclassical conditions can lead to novel interfacial processes, the reader is directed to studies on potentialinduced structural transitions of electrodes including surface reconstruction and dissolution, 78 formation of ion concentration gradients, 160,166,167 and formation of strong interfacial electric fields. 14,161 These phenomena synergistically modify microenvironments around active sites, and we see many avenues for investigations on how correlated double layer formation influences electrocatalytic activity.…”

Local reaction environment in electrocatalysis

“…The local environment refers to reaction conditions at or near the electrode-electrolyte interface, where charge and electron transfer occurs. The evolutions of reaction pathways in multi-phase electrocatalysis are sensitive and significantly influenced by interfacial conditions, such as the local concentration of reactants, 30,31 the interfacial hydrophobicity, 32,33 the local pH, 34 and organic additives (Fig. 1).…”