In this work, a novel single-atom alloy electrocatalyst (SAAE) was developed for enhanced electrocatalysis in next-generation energy technologies. The catalyst, composed of single-atom Rh and bulk Ni on FeV3O8 support, overcomes challenges related to stability and efficiency in electrochemical reactions. The work function difference between Rh and Ni, as confirmed by computational and synchrotron-based analysis, facilitates superior electric polarization and ohmic contact with FeV3O8. The FeV3O8@RhNi demonstrates outstanding performance in oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs), with high half-wave potential (0.90 V) and low overpotential (120 mV at 10 mA cm−2). In zinc-air batteries, it maintains a stable discharge–charge voltage gap, specific capacity of 810 mAh·g−1, peak power density of 186 mW·cm−2 at 320 mA·cm−2, and cycle stabilities exceeding 859 h at 10 mA·cm−2. The catalyst also proves its durability in flexible zinc–air batteries, indicating its potential for efficient electrocatalytic reactions in emerging energy technologies.

The integration of bifunctionally active sites of multielement random alloy catalysts with other metal oxide electrocatalysts is a promising strategy for efficient electrochemical reactions. In this study, a novel combination of virtual crystal approximation and hydrothermal synthesis was used to investigate the composition-dependent structure and electrical property in a Ag1−xNix catalyst. The combination showed that a hexagonal closed-packed structure of Ag1−xNix with a compositional ratio of 6:4 (Ag:Ni) had electrical conductivity of ∼2 × 107 S∙cm−1 and an ionization potential of − 5.4 eV. Furthermore, the bifunctional oxygen electrocatalytic efficiencies of Ag0.6Ni0.4 were improved by forming a heterointerface with the CoNb2O6 electrocatalyst, resulting in a discharge-charge voltage gap of 0.81 V over 587 h, peak power density of 178.9 mW∙cm−2, and specific capacity of 806.8 mA∙h∙g−1 in a zinc–air battery. This approach was applied to pouch-type zinc–air batteries, resulting in long-term stability of over 158.6 h at 10 mA∙cm−2.

In this work, a novel single-atom alloy electrocatalyst (SAAE) was developed for enhanced electrocatalysis in next-generation energy technologies. The catalyst, composed of single-atom Rh and bulk Ni on FeV3O8 support, overcomes challenges related to stability and efficiency in electrochemical reactions. The work function difference between Rh and Ni, as confirmed by computational and synchrotron-based analysis, facilitates superior electric polarization and ohmic contact with FeV3O8. The FeV3O8@RhNi demonstrates outstanding performance in oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs), with high half-wave potential (0.90 V) and low overpotential (120 mV at 10 mA cm−2). In zinc-air batteries, it maintains a stable discharge–charge voltage gap, specific capacity of 810 mAh·g−1, peak power density of 186 mW·cm−2 at 320 mA·cm−2, and cycle stabilities exceeding 859 h at 10 mA·cm−2. The catalyst also proves its durability in flexible zinc–air batteries, indicating its potential for efficient electrocatalytic reactions in emerging energy technologies.

The integration of bifunctionally active sites of multielement random alloy catalysts with other metal oxide electrocatalysts is a promising strategy for efficient electrochemical reactions. In this study, a novel combination of virtual crystal approximation and hydrothermal synthesis was used to investigate the composition-dependent structure and electrical property in a Ag1−xNix catalyst. The combination showed that a hexagonal closed-packed structure of Ag1−xNix with a compositional ratio of 6:4 (Ag:Ni) had electrical conductivity of ∼2 × 107 S∙cm−1 and an ionization potential of − 5.4 eV. Furthermore, the bifunctional oxygen electrocatalytic efficiencies of Ag0.6Ni0.4 were improved by forming a heterointerface with the CoNb2O6 electrocatalyst, resulting in a discharge-charge voltage gap of 0.81 V over 587 h, peak power density of 178.9 mW∙cm−2, and specific capacity of 806.8 mA∙h∙g−1 in a zinc–air battery. This approach was applied to pouch-type zinc–air batteries, resulting in long-term stability of over 158.6 h at 10 mA∙cm−2.

ABSTRACT Diamagnetism expels external magnetic fields due to the orbital motion of electrons (orbital diamagnetism) or the Meissner effect in superconductors. The magnetic susceptibility of orbital diamagnetism is generally very small within the order of 10 −6 to 10 −4 emu cm −3 Oe −1 because the orbital diamagnetism originates from the 2 nd ‐order perturbation of atomic Hamiltonian in fully occupied orbitals. Here, we report the giant negative spin‐polarization (GNSP) in the Fe‐based high entropy alloy NbTaTiZrFe superconductor, synthesized by a powder metallurgical method. This compound exhibits a pronounced diamagnetic response below 42 K, and it reaches up to −60% of diamagnetic external field shielding at the above superconducting transition temperature (T c ) of 6 K in zero‐field‐cooled conditions, transitioning to ferromagnetic behavior under field‐cooled conditions. The itinerant negative spin polarization is supported by substantial diamagnetic signal at low magnetic fields paired with a strong ferromagnetic coercive force (H coer = 1800 Oe), a ferromagnetic spin flip signal exclusive to the diamagnetic state, and metallic diamagnetism verified by scanning magnetic force microscopy, and spin‐resolved density functional theory calculation. The GNSP originated from the strong antiparallel correlation between Fe spins and the other spins of diamagnetic elements by strong Coulomb interaction. The coexistence of GNSP and stable superconductivity strongly implies the possibility of S z = ‐1 type spin‐triplet superconductivity, which can be a promising platform for exploring Majorana fermions and their potential applications in quantum computation.

Heat flux sensors based on the anomalous Nernst effect (ANE) have emerged as a promising solution for achieving thin and flexible designs. ANE-based heat flux sensors typically employ thermopile structures composed of two ANE materials with opposite signs, connected in series to enhance sensing performance. However, a mismatch in the Seebeck coefficient between the two ANE materials causes a considerable offset voltage due to the Seebeck effect (SE) under oblique heat flux. This parasitic sensing voltage hinders direct sensing of heat flux in the intended direction. In this study, a sign-reversed ANE with matched Seebeck coefficient is examined in Fe₃Ln (Ln = Gd, Tb, Dy, Ho, and Er), enabling a thermopile structure free from the SE-induced offset voltage. Based on density functional theory calculations, Fe₃Ln is selected as a suitable candidate for exhibiting sign reversal of ANE while maintaining the Seebeck coefficient. At 300 K, Fe₃Ln (Ln = Gd, Tb, Dy, and Ho) exhibits a positive ANE sign, whereas Fe₃Er exhibits a negative ANE sign, facilitating the combination of two sign-reversed ANE materials. Among these, Fe₃Ho and Fe₃Er demonstrate the lowest Seebeck coefficient difference of 0.45 μV K^-1, minimizing the offset voltage-induced relative uncertainty, as confirmed by COMSOL simulations - comparable to that of other SE-based heat flux sensors. This study paves the way for the development of ANE-based heat flux sensors by introducing a novel approach to pairing opposite-ANE-sign materials with matched Seebeck coefficient, enabling direct and accurate heat flux sensing via thermopile structures.

An itinerant ferromagnet with a cubic structure such as α-Fe has no uniaxial magnetism, while uranium monosulfide US has the strongest-known uniaxial magnetism despite its cubic structure. We probed the cause for this difference by density functional theory (DFT) calculations for α-Fe, FeNi, and US to determine their magnetocrystalline anisotropy energies (MAEs), partial density of states (PDOS) plots, and pair polarization indexes (i.e., the strengths of the pair polarizations), Δ<i>p</i>. By comparing these results with those already reported for MnAl and SmCo₅, we find that the MAEs of these itinerant ferromagnets increase in the order, α-Fe < FeNi < MnAl < SmCo₅ < US, and so do their Δ<i>p</i> values, revealing that US and α-Fe differ in their uniaxial magnetism due to the large difference in their pair polarizations. We also investigated the possibility for pair polarization to induce Jahn-Teller instability by analyzing the weak cubic-to-rhombohedral distortion of US that accompanies its ferromagnetic transition at 177 K to show that this is indeed a weak Jahn-Teller distortion. The absence of such a Jahn-Teller instability in other permanent magnets was ascribed to the weak covalent character of their interatomic bonds.