Nanocrystal (NC) solids are an exciting class of materials, whose physical properties are tunable by choice of the NCs as well as the strength of the interparticle coupling. One can consider these NCs as "artificial atoms" in analogy to the formation of condensed matter from atoms. Akin to atomic doping, the doping of a semiconducting NC solid with impurity NCs can drastically alter its electronic properties. A high degree of complexity is possible in these artificial structures by adjusting the size, shape, and composition of the building blocks, which enables "designer" materials with targeted properties. Here, we present the doping of the PbSe NC solids with a series of Au Ag alloy nanoparticles (NPs). A combination of temperature-dependent electrical conductance and Seebeck coefficient measurements and room-temperature Hall effect measurements demonstrates that the incorporation of metal NPs both modifies the charge carrier density of the NC solids and introduces energy barriers for charge transport. These studies point to charge carrier injection from the metal NPs into the PbSe NC matrix. The charge carrier density and charge transport dynamics in the doped NC solids are adjustable in a wide range by employing the Au Ag NP with different Au:Ag ratio as dopants. This doping strategy could be of great interest for thermoelectric applications taking advantage of the energy filtering effect introduced by the metal NPs.

No abstract

Electrochemical reduction−oxidation processes with the aid of cathode catalysts are promising technologies for the decomposition of organic compounds. High-efficiency and low-cost catalysts for electrochemical reductive dechlorination and two-electron oxygen reduction reaction (ORR) are vital to the overall degradation of chlorinated organic compounds. This study reports electrochemical dechlorination using a single-atom Co-loaded sulfide graphene (Co-SG) catalyst via atomic hydrogen generated from the electrochemical reduction of H 2 O and electrolysis of hydrogen. The Co-SG electrocatalyst exhibited a remarkable performance for H 2 O 2 synthesis with a half-wave potential of 0.70 V (vs RHE) and selectivity over 90%. The high electrochemical performance was achieved for bifunctional electrocatalysis with regard to the smaller overpotentials, faster kinetics, and higher cycling stability compared to the noble metal-based electrocatalysts. In this study, 2,4dichlorobenzoic acid was well degraded and the TOC concentration was effectively reduced. This work introduces the preparation of a new active site for high-performance single-atom catalysts and also promotes its application in the electrochemical degradation of chlorinated organic pollutants.

Electrocatalytic reduction of CO 2 to formate on carbon based electrodes is known to suffer from low electrochemical reaction activity and product selectivity. Pd/three-dimensional graphene (Pd/3D-RGO), In/3D-RGO and Pd-In/3D-RGO for the electrochemical reduction of CO 2 were prepared by a mild method that combines chemical and hydrothermal. The metal/3D-graphenes (metal/3D-RGO) were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry and the ion chromatography were performed to investigate the electrochemical performance of the metal/3D-RGO. The morphology and dispersion of metal/3D-RGO are 3D structure with amount of interconnected pores with metal NPs loading on the fold. And the Pd 0.5 -In 0.5 /3D-RGO show excellent surface performance with well dispersion and smallest particle size (12.8 nm). XPS reveal that binding energy of Pd (In) NPs is shifted to negative energy, for the metal lose electrons in metal and combine with C, which is demonstrated in the HNO 3 experiment. The peak potential of Pd 0.5 -In 0.5 /3D-RGO is À0.70 V (vs. Ag/AgCl), which is more positive than In 1.0 /3D-RGO (À0.73 V) and Pd 1.0 / 3D-RGO (À1.2 V). The highest faradaic efficiency (85.3 %) happens in Pd 0.5 -In 0.5 /3D-RGO at À1.6 V vs. Ag/ AgCl. In these experiments, the special structure that metal NPs combine with C and the bimetal NPs give a direction to convert CO 2 to formate.

No abstract

No abstract

No abstract

No abstract