| dc.description.abstract | Recently, blackening titanium dioxide has attracted attention as a promising catalyst for improving photoelectrochemical activity. It has been investigated for hydrogen production, and it is expected to have enhanced carbon dioxide conversion ability. In this study, a new generation of the titanium oxide catalysts referred to as the black titanium dioxide nanotube (BTNT) is tested to produce hydrogen from water splitting and carbon monoxide from carbon dioxide conversion. BTNT synthesis is optimized through electrochemical anodization and reduction in an ethylene glycol electrolyte. The synthesized material is also compared with the white titanium dioxide nanotube (TNT). The surface morphology, phase crystallinity, and oxidation states are confirmed by characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). SEM shows a uniform nanotube structure with an average pore diameter of 65nm, while XRD indicated anatase crystallinity phase. The photoelectrochemical performance is investigated using the BTNT as a photoanode and a platinum wire as a cathode, where hydrogen was detected online via a residual gas analyzer (RGA). The highest performance is achieved in acidic conditions as the maximum percentage based on the gas sample volume reached 5.15% at an average current density of 1.75 mA/cm2. BTNT is then tested in an electrochemical system to produce a mixture of CO/H2 with a gold cathode. A qualitative model is developed for product analysis based on Fourier-Transform Infrared Spectroscopy (FTIR) and RGA for CO and H2 detection, respectively. BTNT, compared to Pt, requires higher voltages to reach the same current densities and generate an equivalent amount of the product. The final part of this work covers a detailed sustainability analysis of our developed system compared to other electrochemical and conventional CO/H2 production routes. This analysis shows that the developed system needs to achieve higher CO2 conversion to lower the CO2 emissions and operating cost. Comparison with conventional routes showed that the electrochemical path needs further technological advancements that facilitates significant increase in energy efficiency such as lowering the overpotential, combined with substantial decrease in the renewable electricity price that could be achieved as well by new policies that provides incentives for this technology to be economically viable. | en |
