Electrocatalytic oxidation of coal on Ti-supported metal oxides coupled with liquid catalysts for H2 production

Electrocatalytic oxidation of coal on Ti-supported metal/metal oxides coupled with liquid catalysts is systematically investigated as a method of producing hydrogen at the cathode. The composition of the liquid catalyst was varied to determine its effect on the coal electrolysis. A spectrum of byproducts from the coal oxidation at the anode was analyzed. The Ti-supported metal oxide electrodes were prepared by thermal decomposition and characterized by scanning electron microscopy (SEM). X-ray diffraction results show that the composition of the electrodes was Ti/Pt, Ti/RuO₂, Ti/IrO₂ and Ti/IrO₂–RuO₂. Coal oxidation tests on these electrodes indicate that Ti/IrO₂ has the best electrocatalytic activity. Polarization curves reveal that redox catalysts, such as Fe³⁺, K₃Fe(CN)₆, KBr and V₂O₅, bridge the coal particles and the solid electrode surface, thus increasing the rates of coal oxidation. The dynamic transition of Fe³⁺/Fe²⁺ is proven by a KMnO₄ titration experiment, and the possible catalytic mechanism is discussed. Product analysis shows that pure H₂ is generated at the cathode and that CO₂ is the main product at the anode.