Oxygen reduction reaction (ORR) is the key reaction in various electrochemical energy devices. This work reports an inexpensive mesoporous LaMnO3+δ perovskite for ORR with remarkable activity, synthesized by a facile aerosol-spray assisted approach. The mesoporous LaMnO3+δ material shows a factor of 3.1 higher activity (at 0.9 V vs. RHE) than LaMnO3 obtained from co-precipitation method (LMO-CP). Based on results of x-ray absorption near-edge spectroscopy (XANES), x-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) analysis, we conclude that the chemical state of surface Mn and the high surface area are the sources to the notably enhanced activity. The study of Zn-air batteries device further confirmed a Pt/C comparable performance in the practical devices with the novel mesoporous LaMnO3+δ catalyst, where the power density at 200 mA/cm2 is only 2.1% lower than in the battery with same-loaded Pt/C catalyst. Therefore, the high mass activity and low-cost of Mn/La may make LaMnO3+δ further approach to the application of electrochemical devices.
We present a low-cost laboratory X-ray absorption spectrometer that uses a conventional X-ray tube source and bent Johann-type crystal monochromators. The instrument is designed for X-ray absorption spectroscopy studies in the 4–20 keV range which covers most K edges of 3d transition metals and L edges of 5d transition metals and actinides. The energy resolution is typically in the range of 1–5 eV at 10 keV depending on the crystal analyser and the Bragg angle. Measurements can be performed in transmission, fluorescence, and imaging modes. Due to its simple and modular design, the spectrometer can be modified to accommodate additional equipment and complex sample environments required for in situ studies. A showcase of various applications is presented.
An in‐situ laboratory‐based X‐ray Absorption Near Edge Structure (XANES) Spectroscopy set‐up is presented, which allows performing long‐term experiments on a solid catalyst at relevant reaction conditions of temperature and pressure. Complementary to research performed at synchrotron radiation facilities the approach is showcased for a Co/TiO2 Fischer‐Tropsch Synthesis (FTS) catalyst. Supported cobalt metal nanoparticles next to a (very small) fraction of cobalt(II) titanate, which is an inactive phase for FTS, were detected, with no signs of re‐oxidation of the supported cobalt metal nanoparticles during FTS at 523 K, 5 bar and 200 h, indicating that cobalt metal is maintained as the main active phase during FTS.