This work reports a novel approach for the synthesis of FeCo alloy nanoparticles (NPs) embedded in the N,P-codoped carbon coated nitrogen-doped carbon nanotubes (NPC/FeCo@NCNTs). Specifically, the synthesis of NCNT is achieved by the calcination of graphene oxide-coated polystyrene spheres with Fe 3+ , Co 2+ and melamine adsorbed, during which graphene oxide is transformed into carbon nanotubes and simultaneously nitrogen is doped into the graphitic structure. The NPC/FeCo@NCNT is demonstrated to be an efficient and durable bifunctional catalyst for oxygen evolution (OER) and oxygen reduction reaction (ORR). It only needs an overpotential of 339.5 mV to deliver 10 mA cm −2 for OER and an onset potential of 0.92 V to drive ORR. Its bifunctional catalytic activities outperform those of the composite catalyst Pt/C + RuO 2 and most bifunctional catalysts reported. The experimental results and density functional theory calculations have demonstrated that the interplay between FeCo NPs and NCNT and the presence of N,P-codoped carbon structure play important roles in increasing the catalytic activities of the NPC/FeCo@NCNT. More impressively, the NPC/FeCo@NCNT can be used as the air-electrode catalyst, improving the performance of rechargeable liquid and flexible all-solid-state zinc-air batteries.

P-NiMoP nanorods (NRs) comprising tri-phases of MoP2, Ni3P and MoO2 with rich crystalline interfaces and oxygen vacancies in MoO2 have been synthesized by plasma-assisted phosphorization of NiMoO4 NRs.

An approach, i.e., atmospheric-pressure nonequilibrium oxygen plasma jet technology, has been reported for the first time to in situ prepare ultrathin nonstoichiometric nickel oxide layers with mixed Ni 3+ /Ni 2+ ions and rich oxygen defects on the surface of three-dimensional (3D) nickel foams (APPJ-Ni x O y /NFs). It depends on the bombardment of the highly reactive energetic species (including O, OH • , O 2 + , and e) with the NF to form the oxide layer in an ultrafast way. The specific feature of the plasma technology gives rise to the simultaneous formation of mixed Ni 3+ /Ni 2+ ions and rich oxygen defects in the APPJ-Ni x O y /NFs. Specifically, for the APPJ-Ni x O y /NFs formed in a short time of 5 min, they show remarkably high catalytic activities and excellent stability for the oxygen evolution reaction (OER). They only need an onset potential of 1.490 V and an overpotential of 355 mV to drive a current density of 10 mA cm −2 . They also exhibit faster reaction kinetics and a lower Tafel slope (88 mV dec −1 ). The presence of mixed Ni 3+ /Ni 2+ ions and rich oxygen defects plays an important role in the high catalytic activities of the APPJ-Ni x O y / NFs. Density functional theory (DFT) calculations indicate that the heterojunction between the Ni x O y layer and the NF greatly reduces the U L (OER) value, which also contributes to the high catalytic activities of the APPJ-Ni x O y /NFs. The work reported here provides a potential approach to fabricating transition metal oxide layers with enhanced catalytic activities for overall water splitting.

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