Zeolitic imidazolate framework-8 is obtained rapidly within 30 min via ultrasonic-assisted solvothermal method. The structure, elemental composition and morphology are investigated by X-ray diffraction, energy-dispersive X-ray detector, scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller. The results show that Zeolitic imidazolate framework-8 nanocrystals possess cubic sodalite-related structure and provide more active sites for adsorption. Furthermore, the prepared Zeolitic imidazolate framework-8 nanocrystals have been examined for the electrochemical sensor of dopamine using cyclic voltammetry and differential pulse voltammetry techniques. The electrochemical studies demonstrate that the modified electrode displayed enhanced catalytic activity in the process of oxidation of dopamine when the working potential is −100 mV. Additionally, we use the sensor to detect dopamine linearly over a concentration range from 5.0 × 10 −8 to 2.0 × 10 −5 M with a lower detection limit of 1.95 × 10 −7 M (S/N = 3). Importantly, Zeolitic imidazolate framework-8 nanocrystals modified electrode showes favorable anti-interference ability and long-term stability.
Nano-tungsten carbide was prepared by intermittent microwave heating method (IMH) in this study. IMH has many advantages such as heating uniformity, rapid increase of temperature in heating. The method is easy to control. AuPdPt-WC/C was prepared by direct chemical reduction. The electrocatalysts are characterized by XRD, SEM, EDX, linear sweeping voltammetry and electrochemical impedance spectroscopy (EIS) for the HER in the acidic media. The results show that the AuPdPt-WC/C electrocatalyst has higher activity and stability in acidic solution compared to the Pt-WC/C electrocatalyst, and AuPdPt-WC/C electrocatalyst performs a lower overpotential and a higher exchange current density. In addition, the catalytic HER performance of AuPdPt-WC/C electrocatalyst is improved dramatically. When the mass ratio of Au:Pd:Pt:WC is 1:1:2:1, the composite electrocatalyst shows the best catalytic activity of the HER. Kinetic study shows that the HER on the AuPdPt-WC/C electrocatalyst gives a lower overpotential in 2.0 mol L −1 H 2 SO 4 solution. When the temperature changed from 313 K to 323 K, the hydrogen evolution performance can also be enhanced.
Producing chemical fuels from sunlight is a sustainable way to utilize solar energy and reduce carbon emissions. Within the current photovoltaic-electrolysis or photoelectrochemical-based solar fuel generation system, electrochemical CO2 reduction is the key step. Although there has been important progress in developing new materials and devices, scaling up electrochemical CO2 reduction is essential to promote the industrial application of this technology. In this work, we use Ag and In as the representative electrocatalyst for producing gas and liquid products in both small and big electrochemical cells. We find that gas production is blocked more easily than liquid products when scaling up the electrochemical cell. Simulation results show that the generated gas product, CO, forms bubbles on the surface of the electrocatalyst, thus blocking the transport of CO2, while there is no such trouble for producing the liquid product such as formate. This work provides methods for studying the mass transfer of CO, and it is also an important reference for scaling up solar fuel generation devices that are constructed based on electrochemical CO2 reduction.
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