Supply Risk Considerations for Photoelectrochemical Water Splitting Materials

The goal of a sustainable energy future has amplified the importance of Green Hydrogen – an energy carrier that promises a cleaner environment without the emission of greenhouse gases. However, the production capacity of Green Hydrogen through electrolyzers remains constrained due to limited supply of renewable power, necessitating advanced research, and technological innovations. One such potential alternative is photoelectrochemical (PEC) water splitting, which converts and stores energy from solar radiation directly via splitting of water into hydrogen and oxygen.<br/>In order to upscale the PEC technology in the future, frequently the need for high abundance of used materials in PEC water splitting is mentioned, however a quantitative analysis has not been performed so far.<br/>This study delves into the supply risks associated with various materials currently under research for PEC water splitting. Utilizing Raw Material Criticality Assessment methods, we evaluate the present and future supply risks of selected PEC materials to determine their viability for large-scale Green Hydrogen. Recognizing the nascent stage of extensive PEC installations, our analysis differentiates the supply risk between present and future scenarios.<br/>Our findings indicate that, in the present, the lowest supply risk is given for α-Fe₂O₃, CuO, and Cu₂O, followed by Ta₃N₅. However, projections suggest that a-SnWO₄ will have an even lower supply risk score in the future, hinting at a potential shift in the research landscape which is currently dominated by other materials including BiVO₄ and a-Fe₂O₃. These materials show higher supply risk scores in our future assessment. Additionally, we quantify the potential surge in demand that would accompany the large-scale deployment of the most promising PEC materials.<br/><br/>[1] M. Hillenbrand, C. Helbig, R. Marschall, <i>Energy Environ. Sci.</i>, 2024,<b>17</b>, 2369-2380 .