Simulations for Charge Transfer and Photocurrent Calculations Using Hematite for Green Hydrogen Production

Hydrogen is an important material for today's economy and a possible clean fuel. "Blue" and "green" hydrogen production rely on catalysts to either convert carbon monoxide into carbon dioxide via the water-gas shift reaction (WGSR) or generate hydrogen with no carbon involved by water splitting. Hematite is a possible catalyst for both reactions, but some limits prevent it from being used commercially. By using a wave propagation simulator, we examined the charge transfer mechanism of hematite during catalysis and found that the *O intermediate has the slowest transfer rate. We were also able to utilize the charge transfer simulation to calculate the probability of a charge to reach the surface, which is essential for generating photocurrent. Using these probabilities and a previously built kinetic Monte Carlo simulation, we were able to simulate J-V curves with a good match to experiments. Using the split-operator method to simulate wave propagation, it is possible to calculate the hole flux to the surface in hematite OER catalysis. The flux can then be translated to photocurrent to predict the dependence of voltage on photocurrent.