Branched Pd@Rh core@shell nanocrystals with exposed Rh {100} facets: an effective electrocatalyst for hydrazine electro-oxidation

Anodic hydrazine electrooxidation boosted overall water electrolysis by bifunctional porous nickel phosphide nanotubes on nickel foam

Water electrolysis is an environmentally friendly and sustainable technique for ultra-pure hydrogen production, while expensive electrode materials and high driving voltage have seriously hindered its commercialization process. Here, Earth-abundant bifunctional porous Ni2P hollow nanotubes on nickel foam (Ni2P-HNTs/NF) electrocatalysts are synthesized through a facile self-template method and a phosphating process, which are perfectly combined with the hydrazine electrooxidation reaction (HzOR) boosted water electrolysis. Benefiting from the unique structural characteristic of open-framework and abundant step atoms, Ni2P-HNTs/NF achieves 10 mA cm-2 at 91 mV (vs. RHE) for the cathodic hydrogen evolution reaction and 18 mV (vs. RHE) for the anodic HzOR in a three electrode system, respectively. The corresponding two-electrode hydrazine electrolyzer produces 10 mA cm-2 with a total voltage of only 152 mV for ultra-pure hydrogen production, highlighting a cost-effective and energy-saving water electrolysis mode.

Porous PdRh nanobowls: facile synthesis and activity for alkaline ethanol oxidation

Optimizing structure and composition with respect to electrocatalytic performance is critical to achieve outstanding Pd-based electrocatalysts. Herein, we have successfully developed a novel electrocatalyst of hollow and porous PdRh nanobowls (PdRh NBs) for the ethanol oxidation reaction (EOR) by using urea as a guiding surfactant. Under alkaline hydrothermal conditions, urea molecules can release bubbles (NH3 and CO2) that in turn guide the formation of PdRh nanobowls. The porous bowl-like structures of PdRh NBs expose abundant surface sites, which allows for increased collision frequency via confining reactants within open spaces. In regards to composition, the reason for introducing Rh is that not only is the redox potential of Rh approximate with that of Pd (beneficial to the formation of high PdRh alloy phase), but also it can effectively facilitate the breakage of C-C bond on the electrode surface (enhancing the total oxidation of ethanol to CO2). Benefiting from the compositional and structural advantages, the newly developed PdRh NBs exhibit significantly improved electrocatalytic activity for the EOR compared with those of the pure Pd NBs, PdRh nanoparticles (PdRh NPs) and commercial Pd black. These attributes might make them good anodic candidates for application in direct ethanol fuel cells.