Activity and stability of the Ni(OH)2MnOx/C composite for oxygen reduction reaction in alkaline solution

Steps towards highly-efficient water splitting and oxygen reduction using nanostructured β-Ni(OH)2

β-Ni(OH)2 nanoplatelets are prepared by a hydrothermal procedure and characterized by scanning and transmission electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and X-ray photoelectron spectroscopy. The material is demonstrated to be an efficient electrocatalyst for oxygen reduction, oxygen evolution, and hydrogen evolution reactions in alkaline media. β-Ni(OH)2 shows an overpotential of 498 mV to reach 10 mA cm-2 towards oxygen evolution, with a Tafel slope of 149 mV dec-1 (decreasing to 99 mV dec-1 at 75 °C), along with superior stability as evidenced by chronoamperometric measurements. Similarly, a low overpotential of -333 mV to reach 10 mA cm-2 (decreasing to only -65 mV at 75 °C) toward hydrogen evolution with a Tafel slope of -230 mV dec-1 is observed. Finally, β-Ni(OH)2 exhibits a noteworthy performance for the ORR, as evidenced by a low Tafel slope of -78 mV dec-1 and a number of exchanged electrons of 4.01 (indicating direct 4e--oxygen reduction), whereas there are only a few previous reports on modest ORR activity of pure Ni(OH)2.

Enhanced Electrocatalytic Oxygen Reduction on NiWOx Solid Solution with Induced Oxygen Defects

The continuous solid solution NiWO_x is successfully prepared by using precursor W₁₈O₄₉ with plenty of oxygen defects. The NiWO_x nanoparticles are characterized by X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray absorption spectroscopy. The crystallographic phase of NiWO_x is stable and characterized by the same feature of the parent lattice W₁₈O₄₉ even with various concentrations of dopant Ni which indicates the existence of oxygen defects. The NiWO_x nanoparticles could be processed as the appropriate promoter after loading 10 wt % Pt. The Pt/NiWO_x displays remarkable response for oxygen reduction reaction in alkaline medium compared with the commercial Pt/C. The analysis of the electrochemistry data shows that the existence of abundant oxygen defects in the solid solution NiWO_x is the key factor for the improved ORR catalyst performance. Ni is effective in the catalysts because of its compatibility with W in the solid solution and its active participation in oxygen reduction reaction.

Nanostructured platinum-free electrocatalysts in alkaline direct alcohol fuel cells: catalyst design, principles and applications

A review of the fundamental principles that allow for the intelligent design and synthesis of non-precious metal nanostructured electrocatalysts for ADAFCs.

Graphene-based transition metal oxide nanocomposites for the oxygen reduction reaction

The development of low cost, durable and efficient nanocatalysts to substitute expensive and rare noble metals (e.g. Pt, Au and Pd) in overcoming the sluggish kinetic process of the oxygen reduction reaction (ORR) is essential to satisfy the demand for sustainable energy conversion and storage in the future. Graphene based transition metal oxide nanocomposites have extensively been proven to be a type of promising highly efficient and economic nanocatalyst for optimizing the ORR to solve the world-wide energy crisis. Synthesized nanocomposites exhibit synergetic advantages and avoid the respective disadvantages. In this feature article, we concentrate on the recent leading works of different categories of introduced transition metal oxides on graphene: from the commonly-used classes (FeOx, MnOx, and CoOx) to some rare and heat-studied issues (TiOx, NiCoOx and Co-MnOx). Moreover, the morphologies of the supported oxides on graphene with various dimensional nanostructures, such as one dimensional nanocrystals, two dimensional nanosheets/nanoplates and some special multidimensional frameworks are further reviewed. The strategies used to synthesize and characterize these well-designed nanocomposites and their superior properties for the ORR compared to the traditional catalysts are carefully summarized. This work aims to highlight the meaning of the multiphase establishment of graphene-based transition metal oxide nanocomposites and its structural-dependent ORR performance and mechanisms.

Layer-by-layer motif hybridization: nanoporous nickel oxide flakes wrapped into graphene oxide sheets toward enhanced oxygen reduction reaction

Herein we report a novel strategy involving the hybridization of nanoporous NiO flakes with graphene oxide (GO) sheets.

Novel Pd-decorated amorphous Ni–B/C catalysts with enhanced oxygen reduction reaction activities in alkaline media

Pd-decorated amorphous Ni–B/C catalysts were successfully synthesized which exhibited enhanced oxygen reduction reaction activities in alkaline media.