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Stable and efficient single atom catalysts (SACs) are highly desirable yet challenging in catalyzing acidic oxygen evolution reaction (OER). Herein, we report a novel iridium single atom catalyst structure, with atomic Ir doped in tetragonal PdO matrix (IrSAs-PdO) via a lattice-confined strategy. The optimized IrSAs-PdO-0.10 exhibited remarkable OER activity with an overpotential of 277 mV at 10 mA·cm−2 and long-term stability of 1000 h in 0.5 M H2SO4. Furthermore, the turnover frequency attains 1.6 s−1 at an overpotential of 300 mV with a 24-fold increase in the intrinsic activity. The high activity originates from isolated iridium sites with low valence states and decreased Ir-O bonding covalency, and the excellent stability is a result of the effective confinement of iridium sites by Ir-O-Pd motifs. Moreover, we demonstrated for the first time that SACs have great potential in realizing ultralow loading of iridium (as low as microgram per square center meter level) in a practical water electrolyzer. [ABSTRACT FROM AUTHOR]

The precision of the weak equivalence principle (WEP) test using atom interferometers (AIs) is expected to be extremely high in microgravity environment. The microgravity scientific laboratory cabinet (MSLC) in the China Space Station (CSS) can provide a higher-level microgravity than the CSS itself, which provides a good experimental environment for scientific experiments that require high microgravity. We designed and realized a payload of a dual-species cold rubidium atom interferometer. The payload is highly integrated and has a size of 460 mm × 330 mm × 260 mm . It will be installed in the MSLC to carry out high-precision WEP test experiment. In this article, we introduce the constraints and guidelines of the payload design, the compositions and functions of the scientific payload, the expected test precision in space, and some results of the ground test experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Co single atoms can induce electron delocalization and spin-state change of FePc. • The FePc-Co-N 3 is the main active site for ORR confirmed by EXAFS and In-situ Raman spectra. • The Al-air battery with FePc@Co-SAs/PCNF shows good feasibility for practical application. Aluminum-air batteries (AABs) have received increasing interest for next-generation energy conversion systems. However, the development of AABs is hindered by the sluggish kinetics of cathodic oxygen reduction reaction (ORR). Iron phthalocyanine (FePc) is one of the active electrocatalysts for ORR but still far from Pt-based materials in terms of electrocatalytic performance. Herein, FePc molecules anchored on the Co single atoms/ N -doped porous carbon nanofibers (denoted as FePc@Co-SAs/PCNF) with enhanced electronic interaction are prepared for the ORR. X-ray absorption spectra (XAS) analysis confirms the atomically dispersed Fe and Co sites and reveals the electronic interaction between FePc and Co-N 3. The cobalt single atoms can break the electronic distribution symmetry of FePc and induce electronic localization to boost the ORR performance. As a result, the FePc@Co-SAs/PCNF electrocatalyst demonstrates a remarkable ORR activity in both alkaline and neutral electrolytes. The electrocatalytic ORR processes on the FePc@Co-SAs/PCNF are recorded by in-situ Raman spectra. Moreover, the ORR mechanism is discussed, which is supported by density functional theory (DFT) calculations. Furthermore, the AABs based on FePc@Co-SAs/PCNF exhibit remarkable discharge performance. This study offers a new strategy for rationally designing metallic macrocyclic compound electrocatalysts and promotes the development of metal-air batteries. [ABSTRACT FROM AUTHOR]