Theory-guided electrocatalyst engineering: From mechanism analysis to structural design

The exploitation of competent electrocatalysts is a key issue of the broad application of many promising electrochemical processes, including the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), the oxygen reduction reaction (ORR), the CO2 reduction reaction (CO2RR) and the nitrogen reduction reaction (NRR). The traditional searches for good electrocatalysts rely on the trial-and-error approaches, which are typically tedious and inefficient. In the past decades, some fundamental principles, activity descriptors and catalytic mechanisms have been established to accelerate the discovery of advanced electrocatalysts. Hence, it is time to summarize these theory-related research advances that unravel the structure-performance relationships and enables predictive ability in electrocatalysis studies. In this review, we summarize some basic aspects of catalytic theories that are commonly used in the design of electrocatalysts (e.g., Sabatier principle, d-band theory, adsorption-energy scaling relation, activity descriptors) and their relevance. Then, we briefly introduced the fundamental mechanisms and central challenges of HER, OER, ORR, CO2RR and NRR electrocatalysts, and highlight the theory-based efforts used to address the challenges facing these electrocatalysis processes. Finally, we propose the key challenges and opportunities of theory-driven electrocatalysis on their future.