Operando Monitoring and Deciphering the Structural Evolution in Oxygen Evolution Electrocatalysis

Abstract

The oxygen evolution reaction (OER) acts as the bottleneck of some crucial energy conversion and storage technologies involving water electrolysis, CO2 electrolysis, and metal‐air batteries, among others. The challenging sluggish reaction kinetics of the OER can be overcome via developing highly efficient electrocatalysts, which experience a dynamic structural evolution process during the reaction. However, the reaction mechanism of the structural transformation of electrocatalysts during the OER and the structure‐activity correlation in understanding the real active sites remain elusive. Fortunately, operando characterizations offer a platform to study the structural evolution processes and the reaction mechanisms of OER electrocatalysts. In this review, using several in situ/operando techniques some recent advances are elaborated with emphases on tracking the structural evolution processes of electrocatalysts, recording the reaction intermediates during electrocatalysis, and building a link between the structure and activity/stability of electrocatalysts. Moreover, theoretical considerations are also discussed to assist operando characterization understanding. Finally, some perspectives are provided which are expected to be helpful to tackle the current challenges in operando monitoring and unraveling the reaction mechanisms of OER electrocatalysts.

Artificially steering electrocatalytic oxygen evolution reaction mechanism by regulating oxygen defect contents in perovskites

“…S40A) and ~597 cm −1 (fig. S40D) are associated with the formation of CoOOH species, which indicates that LSCO-0.05-0h and LSCO-0.625-6h are working with LOM ( 36 – 38 ), while the unchanged spectra of LSCO-0.05-6h and LSCO-0.625-0h indicate the AEM mechanisms. Despite the fact that LOM is coupled with amorphization or surface reconstruction, this amorphization process is the dynamic structural evolution of the material in the catalytic process under the application of OER voltage.…”

Surface decorated Ni sites for superior photocatalytic hydrogen production

“…This viewpoint is further demonstrated by electrochemical impedance spectroscopy (FigureS13). Lower charge-transfer resistance for CdS@Ni has been confirmed by the evidence that a smaller arch is detected [53][54][55][56]. Photo-irradiation can further decrease the arc diameter, suggesting that the isolated Ni atoms act as electron collectors to facilitate the separation of photogenerated electron-hole pairs on the CdS@Ni interface.…”

Kinetic Regulation Engineering and In‐Situ Spectroscopy Studies on Transition‐Metal‐Based Electrocatalysts for Water Splitting

“…The application of infrared spectroscopies in chemistry can be divided into two aspects: basic research of molecular structure and analysis of chemical composition. [116] Infrared spectroscopy can be used to infer the unknown structure according to the position and shape of the absorption peak in the spectrum, and determine the content of each component in the mixture according to the intensity of the characteristic absorption peak. [117] In-situ Infrared is used to directly conduct infrared analysis of the product during reaction, and test the changes in the structure of functional groups, which can better simulate the experimental process and is very helpful to explain the reaction mechanism (Figure 8a).…”

“…Infrared spectroscopy provides fingerprinting of polarized free radicals for key oxygen intermediates involved in OER and is concentrated within a window of 800-1600 cm À 1 . [116][117][118] Liu et al [119] reported an amino-rich layered network carbon (amino-HNC) loaded on carbon paper, and by using in situ infrared spectroscopy, in the OER process in the acid medium, the key structural evolution of H 2 NÀ (*OÀ C)À C formed by adsorption of *O intermediates on the active H 2 NÀ C=C moiety was observed (Figure 8b). Furthermore, they reported a lattice strain NiFe-MOF as an OER electrocatalyst.…”