Investigation on the reaction mechanisms between RE-W cathode and carbon dioxide at 1273 K

•RE-W cathode was oxidized in CO2 atmosphere at 1273 K.•Blue tungsten (WO2.83) film was the main oxidation product.•Increasing heating time made the WO2.83 film thicker and more compact.•Incrassate WO2.83 film terminated the oxidization reaction.

Potential chemical reactions of rare earth-tungsten (RE-W) cathode and carbon dioxide (CO2) gas at 1273 K were examined. The structures, morphologies and distribution of elements on the RE-W cathode surfaces were explored using X-ray diffraction, field emission scanning electron microscopy and energy dispersive analysis. Reactions on the RE-W cathode surfaces were observed as the samples were heated in CO2 atmosphere under various heating times. Blue tungsten (WO2.83) thin film was formed and verified as the primary product, whereas the CO gas and carbon black were the two other by-products of the chemical reactions that happened between CO2 gas and bulk tungsten. WO2.83 thin film, which was adhered firmly on the RE-W cathode surface, became thicker and more compact with increased heating time. Finally, the oxidization reaction was terminated when the experimental time exceeded 18 h.

Graphical abstractSurface structures and morphologies of RE-W cathode change with varying heating times.Figure optionsDownload full-size imageDownload as PowerPoint slide