Exploration and Insight of Dynamic Structure Evolution for Electrocatalysts

Conspectus Electrochemical energy technology is crucial for transitioning from fossil fuels to renewable energy sources due to its clean, efficient, and sustainable nature. Electrocatalysts are capable of maximizing energy conversion efficiency in a practical electrochemical energy technology by accelerating the charge transfer at the electrode–electrolyte interface, in which the structure and composition of the electrocatalyst directly determine the catalyst performance. Therefore, advanced electrocatalysts possess not only an optimal structure and composition but also sufficient self-stability in electrochemical processes to achieve continuous and efficient energy conversion. However, the structural evolution of electrocatalysts in various electrocatalytic processes has been gradually revealed and intensified, which hinders the practical application of electrocatalysts in electrochemical energy technology. The electrocatalytic process involves the adsorption and bonding of reactants on active sites, and this results in an instantaneous change in the structure of electrocatalysts. Structural evolution of electrocatalysts proposed here emphasizes the change in the surface or internal structure/composition of electrocatalysts in electrocatalytic reaction systems due to factors such as reaction medium, reactants, potential, and so on. Generally, structural evolution of electrocatalysts involves the transformation of active sites/phases of electrocatalysts under reaction potentials. This process, known as reconstruction, can lead to changes in activity and/or selectivity. Related research focuses on how to control and utilize reconstruction to prepare robust electrocatalysts. However, reconstructed catalysts may not always maintain structural stability and may undergo further structural evolution, such as the loss or passivation of active components, eventually leading to deactivation. This further reconstruction is commonly referred to as electrocatalyst corrosion, which emphasizes the final degradation of catalytic activity due to the structural evolution of electrocatalysts. The related research focuses on the inducement of triggering corrosion and the more critical corrosion prevention strategies. Therefore, it is urgent to clarify the inducement of corrosion and formulate corrosion prevention strategies, such as designing corrosion-resistant electrocatalysts. However, due to the harsh and complex electrochemical environment/conditions and the dynamic and changeable structure evolution behavior of electrocatalysts, it is challenging to clarify the structure evolution mechanism/law and catalytic mechanism. It is also impossible to establish an accurate structure–activity relationship and further guide the design and preparation of high-efficiency corrosion-resistant catalysts. In this Account, we present recent research progress on the structural evolution of electrocatalysts. We first discuss electrocatalyst reconstruction in electrolysis systems, including the behavior and mechanism of reconstruction and several high-efficiency reconstructed catalysts prepared by manipulating reconstruction. We also introduce unique microbially induced synthesis technology that can upgrade reconstruction synthesis. Next, we examine the corrosion of Pt-based catalysts in the oxygen reduction reaction and propose a Pt dissolution mechanism caused by adsorbed oxygenated species. We suggest corrosion-resistant Pt–Ni catalysts, and extendable carbon-coated corrosion resistance strategies are further suggested. Finally, we propose challenges and opportunities for the structural evolution of electrocatalysts in electrochemical energy technologies.