Molybdenum oxide/nickel molybdenum oxide heterostructures hybridized active platinum co-catalyst toward superb-efficiency water splitting catalysis.

A new catalyst has been developed that utilizes molybdenum oxide (MoO3)/nickel molybdenum oxide (NiMoO4) heterostructured nanorods coupled with Pt ultrafine nanoparticles for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) toward industrial-grade water splitting. This catalyst has been synthesized using a versatile approach and has shown to perform better than noble-metals catalysts, such as Pt/C and RuO2, at industrial-grade current level (≥1000 mA·cm-2). When used simultaneously as a cathode and anode, the proposed material yields 10 mA·cm-2 at a remarkably small cell voltage of 1.55 V and has shown extraordinary durability for over 50 h. Density functional theory (DFT) calculations have proved that the combination of MoO3 and NiMoO4 creates a metallic heterostructure with outstanding charge transfer ability. The DFT calculations have also shown that the excellent chemical coupling effect between the MoO3/NiMoO4 and Pt synergistically optimize the charge transfer capability and Gibbs free energies of intermediate species, leading to remarkably speeding up the reaction kinetics of water electrolysis.

Hierarchical Heterostructures of Ultrasmall Fe2O3-Encapsulated MoS2/N-Graphene as an Effective Catalyst for Oxygen Reduction Reaction.

In this study, a facile approach has been successfully applied to synthesize a hierarchical three-dimensional architecture of ultrasmall hematite nanoparticles homogeneously encapsulated in MoS2/nitrogen-doped graphene nanosheets, as a novel non-Pt cathodic catalyst for oxygen reduction reaction in fuel cell applications. The intrinsic topological characteristics along with unique physicochemical properties allowed this catalyst to facilitate oxygen adsorption and sped up the reduction kinetics through fast heterogeneous decomposition of oxygen to final products. As a result, the catalyst exhibited outstanding catalytic performance with a high electron-transfer number of 3.91-3.96, which was comparable to that of the Pt/C product. Furthermore, its working stability with a retention of 96.1% after 30 000 s and excellent alcohol tolerance were found to be significantly better than those for the Pt/C product. This hybrid can be considered as a highly potential non-Pt catalyst for practical oxygen reduction reaction application in requirement of low cost, facile production, high catalytic behavior, and excellent stability.

CuAg@Ag Core-Shell Nanostructure Encapsulated by N-Doped Graphene as a High-Performance Catalyst for Oxygen Reduction Reaction.

Development of a robust, cost-effective, and efficient catalyst is extremely necessary for oxygen reduction reaction (ORR) in fuel cell applications. Herein, we reported a well-defined nanostructured catalyst of highly dispersed CuAg@Ag core-shell nanoparticle (NP)-encapsulated nitrogen-doped graphene nanosheets (CuAg@Ag/N-GNS) exhibiting a superior catalytic activity toward ORR in alkaline medium. The synergistic effects produced from the unique properties of CuAg@Ag core-shell NPs and N-GNS made such a novel nanohybrid display a catalytic behavior comparable to that of the commercial Pt/C product. In particular, it demonstrated a much better stability and methanol tolerance than Pt/C under the same conditions. Because of its outstanding electrochemical performance and ease of synthesis, CuAg@Ag/N-GNS material was expected to be a promising low-cost catalyst for ORR in alkaline fuel cell applications.

Porous Hollow-Structured LaNiO3 Stabilized N,S-Codoped Graphene as an Active Electrocatalyst for Oxygen Reduction Reaction.

A nanohybrid based on porous and hollow interior structured LaNiO3 stabilized nitrogen and sulfur codoped graphene (LaNiO3 /N,S-Gr) is successfully synthesized for the first time. Such a nanohybrid as an electrocatalyst shows high catalytic activity for oxygen reduction reaction (ORR) in O2 -saturated 0.1 m KOH media. In addition, it demonstrates a comparable catalytic activity, longer working stability, and much better alcohol tolerance compared with commercial Pt/C behavior in same experiment condition. The obtained results are attributed to synergistic effects from the enhanced electrocatalytic active sites on the rich pore channels of porous hollow-structured LaNiO3 spheres and heteroatom doped efficiency on graphene structure. In addition, N,S-Gr can meritoriously stabilize monodispersion of the LaNiO3 spheres, and act as medium bridging for high electrical conductivity, thereby providing large active surface area for O2 adsorption, accelerating reduction reaction, and improving electrochemical stability. Such a hybrid opens an interesting class of highly efficient non-Pt catalysts for ORR in alkaline media.