Utilisation of gelatin as nitrogen source for N-doped carbon nanotubes and its performance for the oxygen reduction reaction

Gelatin is utilised as a nitrogen source to synthesise nitrogen (N)-doped carbon nanotubes (CNTs). The N-doped CNT was prepared by mixing gelatin and CNT, followed by calcination at 500 °C and 800 °C under N2 atmosphere. X-ray diffraction analysis shows that the higher gelatin weight ratio results in a decrease of the crystallisation. X-ray photoelectron spectroscopy deconvolution analysis confirms that pyridinic-N and pyrrolic-N have appeared at the surface of the samples. The higher calcination temperature affects the surface properties of N-doped CNT which tend to shift the pyrrolic-N to the pyridinic-N. Cyclic voltammetry analysis reveals that the presences of pyridinic-N and graphitic-N configuration have higher oxygen reduction reaction (ORR) activity compared to the N-pyrrolic structure. © 2022 Vietnam Academy of Science & Technology

Oxygen Plasma Induced Hierarchically Structured Gold Electrocatalyst for Selective Reduction of Carbon Dioxide to Carbon Monoxide

Electrochemical reduction of CO₂ into C1 products with high energy density has attracted attention due to the demands for renewable energy sources. Herein, we demonstrate a selective electrocatalytic CO₂ reduction system where the cathode consists of hierarchically structured Au islands catalysts. To be more specific, the Au islands were prepared by oxygen plasma treatment on the Au foil to increase the current density for the selective production of carbon monoxide with over 95% of faradaic efficiency. Faradaic efficiency, production rate, and the onset potential for CO₂ reduction were significantly improved by the expanded surface area compared with a polycrystalline Au electrode. Furthermore, the performance of CO₂ reduction to CO was enhanced by adding ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) which has high CO₂-capture ability and catalytic activity. On the other hand, the rate-determining step of the Au electrode for the CO production determined by Tafel plots was found to be consistent with the initial one electron transfer step to form the surface-adsorbed CO₂^•– intermediates regardless of the application of hierarchically structured catalyst and ionic liquid in the CO₂ reduction system