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[en] To devise widespread and economical materials to produce hydrogen is fundamental for turning hydrogen into an ideal clean energy source. Many research findings have proved that using 2D structured transition metal dichalcogenides (TMDs) as electro-catalysts is a feasible way to prompt hydrogen evolution reaction (HER) activity. This work exhibits a theoretical research on pristine WS2/GeC and twisted WS2-GeC composites with comprehensive first-principles calculations to lay a theoretical framework on the band re-alignment and kinetic barriers for H2 evolution. The results reveal that the WS2-GeC is a typical well-defined type-II heterostructure, which can effectively separate carriers. A further electronic phase transition from semiconducting to metallic can be obtained by applying the external strain, which originates from the internal energy-level shift. The calculated barrier of Tafel mechanism react with water for H2 evolution is only 0.8 eV when unaxial strain is applied on HS-3. This work not only proposes a detailed HER mechanism of heterostructure, but reveals a new possibility for application in nanomaterials since strain engineering is a flexible and feasible approach. (paper)
[en] A suitable control of the reaction conditions to govern polymer qualities requires a deep understanding of topics such as polymer chemistry, standard thermodynamics, reaction kinetics, colloid science and reaction engineering. Good and reliable models represent a fundamental tool for the solution of this problem. In order to explain the potentials of models, in this paper some significant aspects concerning emulsion polymerization and catalytic Ziegler-Natta polymerization will be illustrated
[en] It is highly challenging to explore high–performance bi-functional oxygen electrode catalysts for their practical application in next-generation energy storage and conversion devices. In this work, we synthesize hierarchical N–doped carbon microspheres with porous yolk–shell structure (NCYS) as a metal-free electrocatalyst toward efficient oxygen reduction through a template-free route. The enhanced oxygen reduction performances in both alkaline and acid media profit well from the porous yolk–shell structure as well as abundant nitrogen functional groups. Furthermore, such yolk–shell microspheres can be used as precursor materials to motivate the oxygen reduction activity of oxygen evolution oriented materials to obtain a desirable bi-functional electrocatalyst. To verify its practical utility, Zn–air battery tests are conducted and exhibit satisfactory performance, indicating that this constructed concept for preparation of bi-functional catalyst will afford a promising strategy for exploring novel metal–air battery electrocatalysts. (paper)
[en] Designing efficient and robust oxygen evolution reaction (OER) electrocatalysts is of great importance for various electrochemical energy storage and conversion applications. Herein, we developed IrP2 nanocrystals uniformly anchored in P,N-codoped carbon nanosheets (IrP2@PNC-NS) as highly active OER electrocatalysts. The ultrathin PNC-NS reconstructs an agaric-like porous structure, which can inhibit the agglomeration of the IrP2 nanocrystals effectively. Moreover, the in-situ phosphatization leads to the formation of a strong electron interaction between PNC-NS and IrP2 nanocrystals, endowing the heterostructure materials with satisfying synergistic effects. Benefiting from the collaborative advantages of ideal configuration structure and favorable synergistic effects, IrP2@PNC-NS exhibits excellent OER performance with a low overpotential of 221 mV at 10 mA cm−2, and a small Tafel slope of 37.5 mV dec−1. DFT calculations reveal that the synergistic effects derived from the IrP2/PNC interfaces, which can effectively tune the activation barriers towards facilitating the oxygen evolution process. This work provides new insight into the design of heterostructure materials for advanced OER electrocatalysts. (paper)
[en] Highlights: • A high mass-transport bioelectrocatalytic interfaces based on a nanoparticle-polymer framework is investigated. • The compatibility of bio- anode and cathode was tested with electrochemical methods. • The bioelectrodes can offer highly efficient membrane-less bioenergy devices. • The biofuel cell delivers a high-power density and open circuit voltage compared to conventional polymer-based biofuel cells. • The nanoparticle-polymer framework could significantly accelerate developments in the field of high-performance bio-energy devices. Bioenergy based devices are rapidly gaining significant research interest because of growing quest for future alternative energy resources, but most of the existing technologies suffer from poor electron transfer and slow mass transport, which hinder the fabrication of realistic high-power devices. Using a versatile strategy, here we have demonstrated the fabrication of nanoparticle-polymer framework based bioelectrocatalytic interfaces which facilitate a high mass-transport and thus offers the simple construction of advanced enzyme-based biofuel cells. It has been shown that a gold nanoparticle-structured polyaniline network can be effectively used as an electrical cabling interface providing efficient electron transfer for bio- anode and cathode. The resulting bioelectrodes are capable of excellent diffusional mass-transport and thus can easily facilitate the design of new and highly efficient membrane-less advanced bioenergy devices. The biofuel cell delivers a high-power density of about 2.5 times (i.e., 685 µW cm−2) and open circuit voltage of 760 mV compared to conventional conducting polymer-based biofuel cells.
[en] We have developed efficient nanostructures of Cu–Co–Ni alloy with varied stoichiometry as an alternative to the costly Pt-based alloys for hydrogen evolution reaction (HER). These nanoparticles were synthesized using the reverse micellar method. The size of the alloy nanoparticles varied from 40 to 70 nm. An enhanced catalytic activity as evident from high current density was observed for these Cu–Co–Ni (111) alloys which follows the Volmer–Heyrovsky mechanism. They have excellent stability (up to 500 cycles) and significant activity in acid media which might be due to the low hydrogen binding energy. (paper)
[en] Bosk-like Co–Sn–Se monocrystals are deposited on porous Ti plate through a hydrothermal method. The prepared Co–Sn–Se was characterized with morphology, composition and electrocatalytic properties. Electrochemical measurements revealed that the Ti/Co–Sn–Se electrodes exhibited great catalytic performance for hydrogen evolution reaction with the low onset overpotential of − 50 mV, the small Tafel slope of 83 mV/dec and good stability over an extended period of 34,000 s. The high electrocatalytic activity of bosk-like Co–Sn–Se monocrystals, the fast electron transfer between electrodes and catalysts, and the high conductivity of Ti contribute to their acceptable electrocatalytic performance.
[en] Highlights: • Phosphorus-doped graphene (P-RGO) was facilely fabricated by a hydrothermal reduction approach. • An effective electrochemical sensor for acetaminophen was developed based on P-RGO materials. • The sensor exhibited enhanced sensitivity, excellent anti-interference ability, reproducibility, and stability. • Satisfying recovery results for acetaminophen detection in real Pharmaceutical tablet samples were achieved. - Abstract: Phosphorus-doped graphene (P-RGO) was synthesized and employed as active electrode material to construct electrochemical sensor for acetaminophen (AP). The P-RGO coated glass carbon electrode (P-RGO/GCE) showed an excellent electrocatalytic activity for the oxidation of AP, resulted from highly enhanced electrochemical conductivity and accelerated electron transfer. The experimental conditions for AP detection were optimized, and under the optimal condition, a linear relationship between current intensity and concentration of AP was obtained in the range of 1.5–120 µM with a detection limit of 0.36 µM (S/N = 3). The developed sensor showed high selectivity for AP in the presence of various common species, excellent reproducibility and stability. The present sensor was also successfully applied for AP detection in pharmaceutical tablet samples.
[en] Graphene is a flat monolayer of sp2 bonded carbon atoms tightly packed into a two-dimensional honeycomb lattice. Graphene sheets have attracted great attention for both fundamental science and applied research due to their high specific surface area, high conductivity, superior optics and mechanical properties. Graphene oxide (GO) is one of the most common precursors for the preparation of graphene. The presence of oxygen-containing functional groups in GO makes it hydrophilic and thus it can be easily dispersed into aqueous solutions. Electrochemical reduction of GO is the reagent free process to prepare graphene, which will henceforth be called as reduced graphene oxide (rGO). In the present study, the aqueous dispersion of GO was drop-casted on glassy carbon (GC) electrode under optimized conditions. Then it was electrochemically reduced in saturated sodium carbonate (Na2CO3) solution. The electron transfer reaction of U(VI)/U(V) redox couple was investigated at rGO in saturated Na2CO3 solution