Hierarchical Flowerlike Highly Synergistic Three-Dimensional Iron Tungsten Oxide Nanostructure-Anchored Nitrogen-Doped Graphene as an Efficient and Durable Electrocatalyst for Oxygen Reduction Reaction.

A unique and novel structural morphology with high specific surface area, highly synergistic, remarkable porous conductive networks with outstanding catalytic performance, and durability of oxygen reduction electrocatalyst are typical promising properties in fuel cell application; however, exploring and interpreting this fundamental topic is still a challenging task in the whole world. Herein, we have demonstrated a simple and inexpensive synthesis strategy to design three-dimensional (3D) iron tungsten oxide nanoflower-anchored nitrogen-doped graphene (3D Fe-WO3 NF/NG) hybrid for a highly efficient synergistic catalyst for oxygen reduction reaction (ORR). The construction of flowerlike Fe-WO3 nanostructures, based on synthesis parameters, and their ORR performances are systematically investigated. Although pristine 3D Fe-WO3 NF or reduced graphene oxides show poor catalytic performance and even their hybrid shows unsatisfactory results, impressively, the excellent ORR activity and its outstanding durability are further improved by N doping, especially due to pyridinic and graphitic nitrogen moieties into a graphene sheet. Remarkably, 3D Fe-WO3 NF/NG hybrid nanoarchitecture reveals an outstanding electrocatalytic performance with a remarkable onset potential value (∼0.98 V), a half-wave potential (∼0.85 V) versus relative hydrogen electrode, significant methanol tolerance, and extraordinary durability of ∼95% current retention, even after 15 000 potential cycles, which is superior to a commercial Pt/C. The exclusive porous architecture, excellent electrical conductivity, and the high synergistic interaction between 3D Fe-WO3 NF and NG sheets are the beneficial phenomena for such admirable catalytic performance. Therefore, this finding endows design of a highly efficient and durable nonprecious metal-based electrocatalyst for high-performance ORR in alkaline media.

Highly Active and Durable Core-Shell fct-PdFe@Pd Nanoparticles Encapsulated NG as an Efficient Catalyst for Oxygen Reduction Reaction.

Development of highly active and durable catalysts for oxygen reduction reaction (ORR) alternative to Pt-based catalyst is an essential topic of interest in the research community but a challenging task. Here, we have developed a new type of face-centered tetragonal (fct) PdFe-alloy nanoparticle-encapsulated Pd (fct-PdFe@Pd) anchored onto nitrogen-doped graphene (NG). This core-shell fct-PdFe@Pd@NG hybrid is fabricated by a facile and cost-effective technique. The effect of temperature on the transformation of face-centered cubic (fcc) to fct structure and their effect on ORR activity are systematically investigated. The core-shell fct-PdFe@Pd@NG hybrid exerts high synergistic interaction between fct-PdFe@Pd NPs and NG shell, beneficial to enhance the catalytic ORR activity and excellent durability. Impressively, core-shell fct-PdFe@Pd@NG hybrid exhibits an excellent catalytic activity for ORR with an onset potential of ∼0.97 V and a half-wave potential of ∼0.83 V versus relative hydrogen electrode, ultrahigh current density, and decent durability after 10 000 potential cycles, which is significantly higher than that of marketable Pt/C catalyst. Furthermore, the core-shell fct-PdFe@Pd@NG hybrid also shows excellent tolerance to methanol, unlike the commercial Pt/C catalyst. Thus, these findings open a new protocol for fabricating another core-shell hybrid by facile and cost-effective techniques, emphasizing great prospect in next-generation energy conversion and storage applications.