Surface states of dual-atom catalysts should be considered for analysis of electrocatalytic activity

Experimentally well-characterized dual-atom catalysts (DACs), where two adjacent metal atoms are stably anchored on carbon defects, have shown some clear advantages in electrocatalysis compared to conventional catalysts and emerging single-atom catalysts. However, most previous theoretical studies directly used a pristine dual-atom site to analyze the electrocatalytic activity of a DAC. Herein, by analyzing 8 homonuclear and 64 heteronuclear DACs structures with ab initio calculations, our derived surface Pourbaix diagrams show that the surface states of DACs generally differ from a pristine surface at electrocatalytic operating conditions. This phenomenon suggests that the surface state of a DAC should be considered before analyzing the catalytic activity in electrocatalysis, while the electrochemistry-driven pre-adsorbed molecules generated from the liquid phase may either change the electronic properties or even block the active site of DACs. Based on these results, we provide a critical comment to the catalyst community: before analyzing the electrocatalytic activity of a DAC, its surface state should be analyzed beforehand. Dual-atom catalysts (DACs) pose several advantages such as uniformity in the active sites and high atom utilization efficiency supported by a synergy of the two catalyst metal atoms. Here, the authors use spin-polarized density functional theory with van der Waals corrections to derive surface Pourbaix diagrams of an Fe-Ni-N-x-C model, showing that the surface states of DACs generally differ from a pristine surface at electrocatalytic operating conditions due to the strong adsorption capacity of a DAC's unique metal-metal bridge site.

Automated summary

By analyzing various DACs structures, the authors find that the surface states of DACs generally differ from a pristine surface at electrocatalytic operating conditions. Therefore, it is important to consider the surface state of a DAC before analyzing its catalytic activity.