Modeling of electrocatalytic hydrogen evolution via high voltage alkaline electrolyzer with different nano-electrocatalysts

Abstract

An energy system based on water for creating hydrogen energy might be less globally restricted than one that uses the available fossil fuels today. Therefore, creating an efficient catalyst and electrolyzer system is necessary to effectively convert renewable energy into chemical energy (hydrogen). In this study, a model based on kinetic reaction rate parameters is proposed for estimating energy efficiency and energy conversion for hydrogen generation in a high-voltage alkaline electrolyzer. Three complementary models, including the thermal, electrochemical, and thermodynamic, are conducted to forecast the thermal time constant, overall thermal resistance, operating temperature, electrolyzer voltage, energy consumption, and energy loss. To ensure that they can operate directly with renewable energy sources, the modeling was expanded to incorporate hydrogen production at a voltage level of 6 V. The model's various parameters were computed using non-linear regression presented in Engineering Equation Solver (EES) utilizing experimental data gathered in a high-voltage alkaline test rig. From their precursors and coated on Ti substrates, nanoparticles of Ag, TiO2, and Ag + TiO2 are created as electrocatalysts for the production of hydrogen. In comparison with the bare Ti electrode, the results revealed that energy efficiencies of the Ag, TiO2, and Ag + TiO2 electrodes have increased by 23%, 28%, and 28%, respectively. The largest improvement in hydrogen energy conversion achieved with TiO2 electrodes over Ti electrodes was 84%. Thermodynamic-thermal models that were integrated showed that the coated electrodes decreased the thermal energy loss (TΔS) and useable energy (ΔG) simultaneously during the electrolysis process. The electrochemical model demonstrated a strong fit to the data from those experiments, indicating that the coated nanomaterials are the most important factor in increasing the electrolyzer energy efficiency-based production of hydrogen. The models presented in this research offered a practical method for increasing hydrogen energy production and energy conversion using nanomaterial to build effective electrolyzer devices. The models described in this study are appropriate for the dynamic simulation of renewable energy-hydrogen systems. As a result, these models are easily connected to economic theories that account for both financial and operation expenses.