Magneto-voltaic activity of single-atom iron on reduced graphene oxide for magneto-catalytic conversion of H2O2into O2

Recent advances in magnetically enhanced (electro)catalysis have disclosed the potential of magnetic fields to modulate reaction kinetics and catalytic performance. Herein, a combination of alternating magnetic field (AMF) as a physical stimulus, reduced graphene oxide (rGO) as a magneto-sensitizer, single-atom Fe on rGO (FeSA:rGO) as the catalytic active site, and H2O2 as a dual reductant and oxidant demonstrated a proof-of-concept magneto-catalytic process that is thermodynamically driven solely by magneto-voltaic activity. Upon application of an AMF to electroconductive FeSA:rGO, AMF-induced charge separation led to formation of low-lying electron holes (EHOMO = 2.41/2.43 eV) and excited electrons (ELUMO = -0.65/-0.57 eV), which triggered AMF power-dependent magneto-voltaic and magneto-electric activity (0.19-1.56 V and 0.15-0.62 mA). In the presence of H2O2, these AMF-induced low-lying electron holes in FeSA:rGO promoted oxidation of the Fe3+ resting state leading to transient formation of a high-valent Fe4+ species, which served as a critical intermediate for magneto-catalytic oxidation of H2O2 and evolution of O2. Furthermore, a kinetic study unveiled that FeSA:rGO concentration, H2O2 concentration, and AMF power played key roles in controlling the rates for FeSA:rGO-mediated magneto-catalytic oxygen evolution reaction. Consequently, these investigations established a mechanistic foundation for the future development of magneto-catalytic systems by integrating AMF-responsive magneto-sensitizers with diverse catalytic active sites.