Considering the trend of energy supply from fossil fuel sources and the environmental consequences and pollution caused by it, its replacement with clean and renewable energy sources is inevitable, especially in developing countries in order to achieve a sustainable future. In this regard, hydrogen produced by water splitting using sunlight as a clean and energy-rich fuel can be used in many parent industries such as steel and petrochemicals and transportation systems. In the field of photoelectrochemical hydrogen production (PEC), most studies have focused on the development of efficient nanostructured materials and less attention has been paid to the optimization of PEC cells. However, cell design greatly affects the overall performance and efficiency of these systems and is a key element for the competitiveness and commercialization of solar hydrogen production. Factors such as the speed of the electrolyte and its distribution pattern, creating a convective current on the catalyst, changes in pH, pressure and temperature of electrolysis, the effective exit of gases from the cell and several other parameters have a significant effect on the overall efficiency of water splitting cells. In this research, a new design for a photoelectrochemical cell for hydrogen production has been done. In this regard, COMSOL Multiphysics simulation software, whose most important features are the ability to integrate different physics and examine their effects on each other, was used to eva‎luate the new cell design. The governing equations of the proposed model include the Navier-Stokes equations in the simulation of the fluid distribution pattern in the cell, the radiant heat transfer equation and the equations related to electrochemistry in the simulation of the water electrolysis environment. Velocity lines, fluid flow distribution map, temperature lines and electrochemical results were presented and analyzed. Based on optimized parameters in fluid design and distribution, the desired cell was made using cnc machine and L316 stainless steel as a substrate for bipolar plates. eva‎luation of cell performance in real conditions using a solar simulator with a power of 1000 W/m2 to provide the radiation spectrum, titanium dioxide with a nanotube structure with a tube length of 270 nm and an outer diameter of 75 nm as an anode photocatalyst with dimensions of cm2 × cm2 and nickel foam coated with Ti/TiN was prepared by physical vapor deposition method and functionalized with platinum nanoparticles as cathode electrocatalyst with cm3 × cm3 dimensions. The microstructures and surface morphology of the applied coatings were analyzed using a scanning electron microscope (FE-SEM) and the stability of the formed structures was analyzed by potentiodynamic polarization and chronoamperometry tests. The results indicated uniform fluid distribution in the cell with a uniformity index of 72%, effective heat transfer at an electrolyte speed of 5 cm/s, and geometric optimization of the anodic photocatalyst substrate in a hole design with a diameter of 300 µm and a distance of 100 µm. Finally, the cell made in laboratory conditions and under the irradiation of light beam with a radiant flux of 1000 W/m2 was able to produce a light current of 0.46 mA at a cell voltage of 1.2 V.

مهران نحوي

ابراهيم افشاري

علي اشرفي , مهدي علي زاده