The development of non-platinum group metal (non-PGM) and efficient multifunctional electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) with high activity and stability remains a great challenge. Herein, by in-situ transforming silver manganese composite oxide heterointerface into boosted Mott–Schottky heterointerface through a facile carbon reduction strategy, a nanorod-like silver/manganese oxide with superior multifunctional catalytic activities for ORR, OER and HER and stability was obtained. The nanorod-like silver/manganese oxide with Mott–Schottky heterointerface (designated as Ag/Mn₃O₄) exhibits an ORR half-wave potential of 0.831 V (vs. RHE) in 0.1 M KOH, an OER overpotential of 338 mV and a HER overpotential of 177 mV at the current density of 10 mA·cm⁻² in 1 M KOH, contributing to its noble-metal benchmarks comparable performance in aqueous aluminum-air (Al-air) battery and laboratorial overall water splitting electrolytic cell. Moreover, in-situ electrochemical Raman and synchrotron radiation spectroscopic measurements were conducted to further illustrate the catalytic mechanism of Ag/Mn₃O₄ Mott–Schottky heterointerface towards various electrocatalytic reactions. At the heterointerface, the Ag phase serves as the electron donor and the active phase for ORR and HER, while the Mn₃O₄ phase serves as the electron acceptor and the active phase for OER, respectively. This work deepens the understanding of the Mott–Schottky effect on electrocatalysis and fills in the gap in fundamental physical principles that are behind measured electrocatalytic activity, which offers substantial implications for the rational design of cost-effective multifunctional electrocatalysts with Mott–Schottky effect.

Aluminum single crystal with 99.999% purity was deformed at room temperature by equal channel angular pressing (ECAP) up to 16 passes. Grain size and misorientation of processed samples were quantitatively characterized by TEM and EBSD. The results show that the refinement efficiency of high purity aluminum single crystal was poor in the initial stage. Extrusion by fewer ECAP passes (n ≤ 8) resulted in only elongated grains containing a large number of subgrains and small misorientations between grains. Stable microstructures of nearly equiaxed grains with high misorientations were obtained by 15 passages, indicating that the initial extremely coarse grains and highly uniform grain orientation are not conducive to the accumulation of strain energy. The initial state of high purity aluminum has a significant effect on the refining efficiency of the ECAP process.

The filling and feeding of thin-walled structures in metal castings pose significant difficulties in manufacturing aerospace structural materials. Samples containing 2 mm and 5 mm thin-walled structures were designed to study the kinetics of filling. The microstructural evolution of the solidification of thin-walled structures was studied with synchrotron X-radiation imaging. The formation of dendritic networks and the isotherm profiles of samples of different thickness were examined. The experimental results showed solidification microstructures of 2 mm and 5 mm thin-walled parts containing elongated equiaxed grains and normal equiaxed grains, respectively. The filling and feeding abilities of thin-walled parts were found to depend more on the wall thickness than on the pouring temperature.