Modeling and analysis of a bias-free hydrogen production approach using perovskite photocathode and lignocellulosic biomass

A model was developed here by simulating the electrolysis system and the photoelectrode separately to evaluate the effect of the degree of PMA reduction and temperature on hydrogen production. [Display omitted] •A model of the bias-free hydrogen production approach was developed.•The effect of temperature was investigated.•The effect of the degree of phosphomolybdic acid reduction was investigated.•The ionic mass transfer under different conditions was analyzed.•Flow system found to enable more adequate ionic mass transfer. The bias-free solar hydrogen production approach using perovskite photocathode and lignocellulosic biomass is a novel hydrogen production approach that can effectively utilize solar energy and biomass energy, along with the production of value-added chemicals. Current research focuses on experimentally finding the optimal conditions for the pre-reduction of phosphomolybdic acid through biomass oxidation. There is little research and modeling of the various factors that may affect the process of phosphomolybdic acid re-oxidation for hydrogen production. A model was developed here to help evaluate these factors by simulating the electrolysis system and the photoelectrode separately. After verifying the reliability of the electrolysis system model and the photoelectrode model, the effect of temperature and the degree of phosphomolybdic acid reduction on the hydrogen evolution rate was investigated. The short circuit current of the photocathode remains almost constant with increasing temperature and degree of phosphomolybdic acid reduction over the voltage range studied. The linear sweep voltammetry curve of the anode for phosphomolybdic acid re-oxidation shifts rightward with increasing temperature by no more than 0.02 V, and shifts leftward with increasing reduction by no more than 0.04 V, which can be almost negligible. As a result, the maximum theoretical current density remains around 20 mA cm-2, indicating that both factors slightly affect the hydrogen evolution rate. At a constant voltage of 0.44 V for 7200 s, the current density of the stationary system decreases by about 46.40%, while that of the flow system decreases by only 2.23%. In conjunction with the analysis of the changes in the concentration distribution of ions inside the electrolysis system, it can be found that the addition of the convection term can help improve ionic mass transfer and prolong the hydrogen production process. This study can provide a reference for the