Cu@N-C with the Cu particles encapsulated in N-doped carbon shells, which was activated by CO2 treatment, is an excellent electrocatalyst for the oxygen reduction reaction.

Graphene oxide (GO) is an attractive freestanding support that can be decorated with ultrathin organic layers for facile and low‐cost fabrication of novel devices with controllable functional properties and microstructures. Here, it is reported that a hybrid material consisting of an ultrathin iron phthalocyanine (FePc) layer self‐assembled on reduced graphene oxide (rGO) exhibits excellent catalytic activity that is superior to that of commercial Pt/C for an oxygen reduction reaction (ORR). During solution processing, the FePc layer is first self‐organized onto GO sheets and then reduced electrochemically to form an FePc/rGO hybrid electrocatalyst. Kinetics studies reveal that the hybrid architecture affords an ultrafast ORR rate caused by a strongly dominant four‐electron process, and the durability of the catalyst shows significant improvement by forming the hybrid structure. Spectroscopic studies suggest that these advantages are afforded by synergistic effects between FePc and rGO, which are enriched by the hybrid structure and the appropriate reduction step.

We analyzed the Fe 3d electronic structure in LiFePO /FePO (LFP/FP) nanowire with a high cyclability by using soft X-ray emission spectroscopy (XES) combined with configuration-interaction full-multiplet (CIFM) calculation. The ex situ Fe L -edge resonant XES (RXES) spectra for LFP and FP are ascribed to oxidation states of Fe and Fe , respectively. CIFM calculations for Fe and Fe states reproduced the Fe L RXES spectra for LFP and FP, respectively. In the calculations for both states, the charge-transfer energy was considerably larger than those for typical iron oxides, indicating very little electron transfer from the O 2p to Fe 3d orbitals and a weak hybridization on the Fe-O bond during the charge-discharge reactions.

Al doping into LiMnO is one of the well-known methods to improve the cycle performance of the LiMnO cathode. We carried out soft X-ray emission spectroscopy (XES) for LiMnO and LiAlMnO to elucidate the relationship between the Mn 3d electronic structures and cycle performances. After the first cycle, the XES spectra of LiAlMnO are almost unchanged compared to the initial state. In contrast, charge-transfer excitation for the XES of LiMnO is significantly reduced, indicating that the Mn 3d-O 2p hybridization in LiMnO should be easily weakened by charge-discharge. In LiAlMnO, the Mn-O bond becomes more stable due to the decrease of Mn ions with Jahn-Teller distortion by Al doping, resulting in the improved cycle performance.