Photoelectrochemical Hydrogen Production using TiO2 Nano-photocatalysts Electrodeposited on Titanium Electrode

Abstract

Water electrolysis is a method of producing hydrogen that is considered highly efficient, with an efficiency of 70-80% and a high purity of more than 99%. However, it requires a large amount of electricity, about 4.5-5.5 kWh per m³ of hydrogen, and thus there is potential for improvement in making the process more sustainable. This is important as hydrogen is seen as a viable, clean, and sustainable energy carrier, particularly considering global warming and the depletion of fossil fuels. This study investigates photonic hydrogen production by using a photoactive coating on an electrode to provide additional photo-current to the photoelectrochemical cell using solar irradiation and electrical energy. Titanium dioxide (TiO2) nanoparticles are used as a coating on a Titanium metal substrate. A bath of TiO2 is prepared using the sol-gel method. The coating is applied by electrochemical deposition in the sol-gel bath. The coated titanium metal is then used as a photocathode in the electrochemical cell, where electrolysis is conducted using sodium sulphate (NaSO4) solution as the electrolyte. The coating is characterized using a Scanning Electron Microscope (SEM) and X-Ray Diffractometer (XRD) to show if the metal is coated adequately with nanoparticles. Moreover, open circuit potential, linear sweep voltammetry, power potentiometry, and galvanostatic power methods are conducted under light, concentrated light, and no-light conditions to study their electrochemical properties. The photoelectrochemical system’s energy, exergy, and hydrogen generation efficiencies are finally computed based on the data acquired. The result of electrochemical characterization shows that the photo-current generated in the system is doubled under concentrated light conditions, in which the photo-current density is calculated as 12.2 A/m2 in concentrated light conditions. Furthermore, SEM results proved that titanium dioxide nanoparticles are present on the coated substrate. From these results, it is determined that by this method, the amount of electrical energy consumption can be reduced due to the additional photo-current achieved by the photoactive electrode. Keywords: Hydrogen, Photoelectrochemical, Electrodeposition, Electrolysis, Photoca