FeCu dual single-atom catalyst reaches 0.88 V half-wave potential for oxygen reduction in 0.1 M KOH
In a laboratory study, Cu atoms placed beside Fe sites in a nitrogen-doped carbon catalyst raised Fe spin polarization; in zinc–air battery tests the material outperformed commercial Pt/C.
A FeCu dual single-atom catalyst on nitrogen-doped carbon (FeCu-NC), with adjacent FeN4 and CuN4 sites, is described in Science China Chemistry (DOI 10.1007/s11426-026-3509-x, dx.doi.org). In the oxygen reduction reaction (ORR) in 0.1 M KOH, the catalyst showed a half-wave potential of 0.88 V versus the reversible hydrogen electrode springer.com
dx.doi.orgspringer.comOpen source ↗. According to the authors, its activity and cycling stability were higher than those of commercial Pt/C. In zinc–air battery tests, FeCu-NC also delivered better discharge performance than Pt/C.
Why the Fe site needed tuning
ORR is the key cathodic process in fuel cells and metal–air batteries, and its sluggish kinetics limit the energy-conversion efficiency of these devices. Fe–N–C single-atom catalysts, which combine high atomic utilization with tunable local electronic structure, are considered one of the most promising alternatives to platinum-based catalysts. However, conventional FeN4 sites adsorb and activate O2 insufficiently, and their adsorption strength toward ORR intermediates is unfavorable. Because the electronic structure and spin state of the Fe center determine how it interacts with oxygen species, the authors set out to regulate that spin state.
Structure and mechanism
Structural characterization showed that Fe and Cu are atomically dispersed and form spatially adjacent Fe–N4 and Cu–N4 coordination structures. In this design, Cu atoms serve as electronic and spin-regulating units for the Fe active centers. Experiments and theoretical calculations together confirmed that the neighboring Cu atoms significantly enhanced spin polarization at the Fe sites.
The spin-state change shifts the Fe d-band center upward and increases the density of reactive states near the Fermi level springer.com
dx.doi.orgspringer.comOpen source ↗. This strengthens the Fe–O2 interaction, which facilitates O2 adsorption and initial activation and accelerates ORR kinetics. The authors describe the result as a neighboring-atom strategy for spin-state regulation in single-atom catalysts and as an account of how the spin state of an active center relates to oxygen activation. The reported data come from laboratory electrochemical measurements and zinc–air battery tests.
