Yongfu Zhu

The oxygen evolution reaction (OER) is central to electrochemical water splitting but remains constrained by sluggish kinetics and catalyst degradation under harsh oxidative conditions. Although many nonprecious electrocatalysts exhibit promising activity at low current densities (10 ∼ 50 mA cm^-2), attaining industrially relevant performance is still impeded by inefficient charge transport and unfavorable adsorption of OER intermediates, particularly at high current densities (∼500 mA cm^-2). Herein, we develop a dual-step hydrothermal strategy to construct ultrathin NiMoO₄·xH₂O nanosheets on 3D nickel foam, followed by controlled Fe incorporation through ion-exchange-driven surface reconstruction. Consequently, the Fe-NiMoO₄·xH₂O electrode achieves an industrial-related current density of 500 mA cm^-2 at a low overpotential of 305 mV with excellent long-term stability. In situ Raman spectroscopy reveals that Fe incorporation promotes the surface reconstruction of NiMoO₄·xH₂O into the catalytically active NiFeOOH phase under OER conditions. Density functional theory (DFT) calculations further demonstrate that, among various 3d transition-metal dopants in the NiMoO₄ lattice, Fe incorporation gives the most thermodynamically stable configuration and the most favorable electronic structure. The resulting local electronic reconfiguration generates Fe-3d-enriched frontier states near the Fermi level (-0.5 to 0 eV), thereby facilitating charge transfer and optimizing the adsorption of OER intermediates. Overall, the integrated structural-electronic modulation optimizes the local atomic environment and accelerates OER kinetics, underscoring local charge engineering as an effective strategy for industrial-grade OER.

Designing heterostructure catalysts with unique interface effects is an effective method for enhancing the activity and stability of the oxygen evolution reaction (OER), which is crucial for advancing large‐scale hydrogen production through water electrolysis. Here, a crystalline NiSe/amorphous NiFe(OH) _x (c‐NiSe/a‐NiFe(OH) _x ) heterostructure catalyst was constructed via a two‐step hydrothermal‐solvent thermal method. Benefiting from the engineered local environment, unique dynamic crystalline–amorphous interfaces, and the charge redistribution, the catalyst exhibits outstanding performance with an ultralow overpotential of 233 mV at 100 mA cm ⁻² . After the stability test for 250 h at a current density of 500 mA cm ⁻² , it retains 93.7% of its initial activity. Density functional theory (DFT) calculations suggest that interfacial electronic modulation optimizes the adsorption energy of the key intermediate *O, thereby accelerating the OER kinetics. This work provides a new design strategy for constructing crystalline–amorphous heterostructure catalysts with both excellent catalytic activity and stability.

Based on a thermodynamic approach, a unified formula was proposed to describe distinct Hall–Petch relationships (HPRs) of unalloyed nanostructured materials (u-NSs: Fe, Cu, Ni, Pd, and Mo) and alloyed ones with low- or high-melting temperature alloying metals (low-T_m or high-T_m a-NSs: Ni_xMo_1−x, Fe_xZr_1−x, Ni_xCu_1−x, and Fe_xCu_1−x). As the grain size decreases to several nanometers, the yield strength first increases and then decreases for u-NSs and low-T_m a-NSs, obeying the inverse HPR (IHPR), while it monotonically increases for high-T_m a-NSs. For the former, the decrease is induced by the reduction in activation energies of interface migration and dislocation gliding, along with the thermally driven decline, lattice expansion, and bond weakening of interface atoms. In the latter case, the monotonic increase or the elimination of IHPR is relevant to the negative interface energy induced by the segregation of alloying atoms at grain boundaries. Our predictions are validated by the available experimental results.

The rational design of CO ₂ electroreduction catalysts requires the establishment of robust structure–activity relationships through precise electronic descriptors.

With the increasing demand for magnesium (Mg) alloys with high strength and good ductility, this study explores high-pressure die-cast (HPDC) Mg-6Al-2RE (AE62), Mg-8Al-2RE (AE82) and Mg-8Al-2RE-0.2Ca (AEX820) alloys (wt. %). Their microstructures and mechanical properties are investigated under both as-cast and T5-aged (direct artificial aging after casting) conditions. HPDC alloys consist of outer fine-grain regions and inner coarse α-Mg grains with abundant eutectic phases. The increasing addition of Al has an insignificant effect on the refinement of the grain size of α-Mg, but it significantly influences the morphology and area fraction of the second phases. The average grain sizes of α-Mg in HPDC AE62, AE82 and AEX820 alloys are approximately 4.0 μm, 3.9 μm and 3.7 μm in the edge regions and about 13.9 μm, 12.8 μm and 12.1 μm in the core regions, respectively. When aged at 200 °C, β-Mg₁₇Al₁₂ precipitates are predominantly formed in the studied alloys. Increasing the Al and Ca concentrations effectively refines the microstructures and enhances the aging hardening response and the strength, albeit at the expense of considerably reduced ductility. The peak-aged AE62 alloys demonstrate balanced tensile properties, with ultimate tensile strength (UTS), yield strength (YS), and elongation at fracture (E_f) at room temperature of ~241 MPa, ~141 MPa and ~7.1%, respectively, and values of ~129 MPa, ~96 MPa and ~19.8%, respectively, at 175 °C. Compared to peak-aged AE62 alloy, the UTS and YS of peak-aged AEX820 alloys are improved by ~6.7% and ~14.2%, respectively, at RT and ~8.5% and ~12.5% at 175 °C, while E_f is decreased by 35.2% at RT and 33.3% at 175 °C, primarily due to the high area fraction of secondary phases.