Synthesis,Structure and Optical Properties of CdO Nanocrystals Directly Grown on Cd Foil

Semiconductor nanocrystals directly grown on the conducting metal can lower the contact resistance and can benefit the electron transfer between the semiconductor and the metal. In the present work, CdO nanocrystals are directly synthesized on the conducting Cd foil through a simple solvothermal method. Cd foil is used as the Cd2＋ source and the substrate. The average size of CdO nanocrystals is -23.1 nm by analyzing the XRD data. Moreover the growth mechanism is discussed. A hierarchic structure characterized by the nano rods and nano particles in the top and bottom layers, respectively, can be observed. From the UV-vis absorption analyzed by Taucs relation, the two different optical band gaps are obtained. The photoluminescence spectrum is obtained and studied.

High-precision regulation synthesis of Fe-doped Co_(2)P nanorod bundles as efficient electrocatalysts for hydrogen evolution in all-pH range and seawater

The hydrogen evolution reaction(HER)via water electrolysis has gained immense research attention.Seawater electrolysis provides great opportunities for sustainable energy production,but is extremely challenging.Transition metal phosphides are promising candidate electrocatalysts.Herein,we prepared a novel Fe-Co_(2)P bundle of nanorods(BNRs)for catalyzing the HER in seawater electrolysis and over the entire p H range.Cobalt phosphides with different crystal phases and morphologies were obtained by varying the Fe doping amount.The Co:Fe molar ratio of 1:0.5 was found to be optimum.The Fe doping improved the HER performance of Co_(2)P over the entire p H range by providing favorable electronic properties and morphology,lattice distortion,and special coordination environment.The Fe-Co_(2)P BNRs showed higher catalytic activity than 20%Pt/C in seawater at high potentials.The density functional theory calculations revealed that the Fe doping reduced the hydrogen binding strength of Co_(2)P to efficiently accelerate the HER kinetics and produce a favorable charge density.This study provides valuable insights into the design and development of high-efficiency HER catalysts for large-scale seawater electrolysis.

Facile synthesis of Pd concave nanocubes： From kinetics to mechanistic understanding and rationally designed protocol

We report a rationally designed one-pot method for the facile synthesis of Pd concave nanocubes in an aqueous solution at room temperature by manipulating the reduction kinetics through the selection of a proper combination of a salt precursor （PdBr4^2-） and reductant （sodium ascorbate）. Our kinetic analysis demonstrates that, through this selection, the nucleation and growth of Pd nanocrystals could be effectively separated into two kinetic regimes involving distinctive reduction pathways： i） solution reduction for the initial formation of single-crystal seeds and ii） surface reduction for the formation of concave nanocrystals via autocatalytic growth from the single-crystal seeds. The suppressed surface diffusion at room temperature, when coupled with the capping effect of bromide ions, ultimately leads to the formation of concave nanocubes with an asymmetric shape and high-index facets, whose synthesis would otherwise require multiple steps and the use of elevated temperatures.

Overpotential-dependent shape evolution of gold nanocrystals grown in a deep eutectic solvent

This paper reports an overpotential-dependent shape evolution of gold nano-crystals （Au NCs） in a choline chloride-urea （ChCl-urea） based deep eutectic solvent （DES）. It was found that the growth overpotentials play a key role in tuning the shape of Au NCs. The shape evolution of Au NCs successively from concave rhombic dodecahedra （RD） to concave cubes, octopods, cuboctahedral boxes, and finally, to hollow octahedra （OH） was achieved by carefully controlling the growth overpotentials in the range from -0.50 to -0.95 V （vs. Pt quasi-reference electrode）. In addition, the presence of urea was important in the shape evolution of Au NCs. The surface structure of the as-prepared Au NCs was comprehensively characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and electrochemical studies. It was demonstrated that the electrocatalytic activity of the as-prepared Au NCs for D-glucose electrooxidation was sensitively dependent on their morphologies. The results illustrated that the dehydrogenated glucose adsorbed on concave RD and concave cubic Au NCs was preferentially transformed to gluconolactone at low electrode potentials. Subsequent gluconolactone oxidation occurred favorably on octopods with {111}-truncated arms and hollow OH at high electrode potential. This study opens up a new approach to develop the surface-structure-controlled growth of Au NCs by combining DES with electrochemical techniques. In addition, it is significant for the tuning of the electrocatalytic properties of NCs.

Heterojunction interface editing in Co/NiCoP nanospheres by oxygen atoms decoration for synergistic accelerating hydrogen and oxygen evolution electrocatalysis

Controllable designing of well-defined heterojunction nanostructures provides an insightful strategy for accelerating the kinetics of the hydrogen and oxygen evolution reactions(HER/OER),but such task is still challenging.Herein,we proposed a protocol of heterojunction interface editing(HIE)strategy by oxygen atoms decoration for synergistic boosting electrocatalytic HER and OER performances.A novel Co/NiCoP nanospheres(NSs)heterojunction was synthesized by crystal seed template transformation method with Ni_(5)P_(4) microspheres as seeds.The effective oxygen atoms interface editing increased the oxidation state of Co atoms and prolonged the Co-P bond length of Co/NiCoP NSs heterojunction,thus the electron localization on P sites was enhanced,leading to the dramatically elevated HER and OER performances simultaneously.The as-constructed O-Co/NiCoP NSs show excellent electrocatalytic activity with 361 and 430 mV vs.reversible hydrogen electrode(RHE)to arrive high current density of 300 mA·cm^(-2)for HER and OER in 1 M KOH as well as good stability.The proposed HIE concept could provide a new perspective on the catalyst design for energy conversion systems.