No abstract

No abstract

No abstract

The controllable assembly of three-dimensional (3D) nano materials from one-dimensional (1D) precursor has always been one of the difficulties in nano material synthesis. Here, we use a gentle hydrolysis of...

The polyhedral Pd nanocrystals are synthesized by a facile conventional hydrothermal method, in which the cetyltrimethylammonium bromide, Fe3+ and formaldehyde are designed as structural orientation, etching and reduction agents, respectively. The crystal and morphological characteristics show that the crystal facets of (111) and (220) planes are exposed on the surface of face‐centered cubic crystal structure of Pd polyhedron. Electrochemical analyses indicate that the polyhedral Pd/XC‐72 catalyst shows the highest electrochemically active surface area (57.6 m2 g−1), similar half‐wave potential and diffusion‐limiting current density (‐4.79 mA cm−2) with state‐of‐the‐art commercial Pd/C in alkaline electrolytes. The excellent electrocatalytic activity supports a four‐electron‐transfer pathway and smaller Tafel slope (67.2 mV dec−1) reveals a higher intrinsic activity for ORR. Additionally, the polyhedral Pd/XC‐72 catalyst also exhibits much better methanol tolerance crossover effects and long‐term stability than commercial Pd/C. All these excellent electrocatalytic performances are considered to be the coaction of the exposed high surface energy facets and more of active sites on the polyhedral crystals surface, which could significantly improve the adsorption and activation energies with oxygenated intermediates in alkaline solution. This work provides a new prospect in designing high active, non‐easy tolerance and more stable Pd‐based catalyst in alkaline fuel cells.

No abstract

By controlling the alkali etching time, the cation and oxygen vacancies contents of CoAl‐LDHs were adjusted. Then CoAl‐layered double oxides catalysts (CoAl‐LDOs‐x) were prepared by calcination and applied to the photothermal catalytic degradation of methanol and acetone under the full spectrum simulated solar illumination. Compared with CoAl‐LDOs‐0 without alkali etching, CoAl‐LDOs‐9 with alkali etching for 9 h showed the most superior photothermal catalytic activity and excellent stability. A series of studies had suggested that the most superior activity of the catalyst could be ascribed to the cation vacancy produced by alkali etching, resulting in more Co3+ active sites on the surface. At the same time, alkali etching also produced oxygen vacancy, which accelerated the adsorption and conversion of surface reactive oxygen species (ROS). In addition, the activation effect of light on lattice oxygen and gas phase oxygen was proved by in‐situ DRIFTS, and the degradation path of methanol was clarified.

No abstract