Direct ethanol fuel cells (DEFCs) have drawn attention for their simplicity, rapid start-up, high power density and environmental friendliness. Despite these advantages, the widespread application of DEFCs faces challenges, primarily due to the inadequate performance of anode and cathode catalysts. Pd-based materials have shown exceptional catalytic activity for both the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR). Alloying noble metals with rare earth elements has emerged as an effective strategy to further enhance the catalytic activity by modulating the electronic structure. In this study, we synthesized a series of palladium-rare earth (Pd₃RE) alloys supported on carbon to serve as bifunctional catalysts that efficiently promote both ORR and EOR. Compared to Pd/C, the Pd₃Tb/C catalyst exhibits 3.1-fold and 1.8-fold enhancement in activity for ORR and EOR, respectively. The charge transfer in the Pd₃Tb/C results in an electron-rich Pd component, thereby weakening the binding energy with oxygen species and facilitating the two reactions.

A heteronuclear dual transition metal atom catalyst is a promising strategy to solve and relieve the increasing energy and environment crisis. However, the role of each atom still does not efficiently differentiate due to the high activity but low detectability of each transition metal in the synergistic catalytic process when considering the influence of heteronuclear induced atomic difference for each transition metal atom, thus seriously hindering intrinsic mechanism finding. Herein, we proposed coordinate environment vary induced heterogenization of homonuclear dual-transition metal, which inherits the advantage of heteronuclear transition metal atom catalyst but also controls the variable of the two atoms to explore the underlying mechanism. Based on this proposal, employing density functional theory study and machine learning, 23 kinds of homonuclear transition metals are doping in four asymmetric C₃N for heterogenization to evaluate the underlying catalytic mechanism. Our results demonstrate that five catalysts exhibit excellent catalytic performance with a low limiting potential of −0.28 to −0.48 V. In the meantime, a new mechanism, “capture–charge distribution–recapture–charge redistribution”, is developed for both side-on and end-on configuration. More importantly, the pronate site of the first hydrogenation is identified based on this mechanism. Our work not only initially makes a deep understanding of the transition dual metal-based heteronuclear catalyst indirectly but also broadens the development of complicated homonuclear dual-atom catalysts in the future.