From Lead Bullets to Solar Cells: A Two-Step Approach to Repurpose Contaminated Lead

Lead perovskite solar cells have emerged as a groundbreaking technology. The unique properties of lead perovskite materials, such as their high absorption coefficient and tunable bandgap, make them ideal candidates for next-generation photovoltaic applications.<br/>Despite their promise, perovskite solar cells pose environmental concerns, particularly in the recycling and sourcing of lead halides. Conventional methods of lead extraction and processing contribute to ecological degradation. To address these challenges, this research proposes a sustainable solution grounded in the principles of a circular economy, aiming to repurpose lead waste into valuable materials for solar cell fabrication.<br/>The environmental challenge posed by lead waste is twofold. On the one hand, there is the potential for lead waste from the burgeoning perovskite industry. On the other, there are existing sources of lead waste, such as metal plating industry, mining industry, homes built before 1986, lead-acid batteries, that are highly contaminated and pose a long-standing environmental hazard. It’s important to note that even so-called “lead-free” plumbing may contain up to 8 percent lead.<br/>Our approach is a two-step process designed to tackle this issue head-on. The first step involves a novel electrochemical method that will be presented in detail at the conference to convert contaminated lead into lead iodide (PbI2). As the lead waste source, we utilized XVII century lead bullet balls. The electrochemical recovery process is robust, accommodating a wide range of contaminants including the 15% Carbon, 10% Oxygen, 0.5% Silicon, 1% Bismuth, 1% Copper, and 1% Zinc we found in the bullets. Remarkably, the process achieves a Faradaic efficiency close to 1, indicating near-complete conversion of lead to PbI2.<br/>The second step involves further purification of the synthesized PbI2 through single-crystal growth. This results in a 35% yield of pure PbI2, with the remaining material being recyclable for subsequent purification loops.<br/>The synthesized PbI2 is not only suitable for immediate use in solar cells but has also been successfully utilized to fabricate a working solar cell. Additionally, it offers a high yield rate of approximately 1g per hour. This yield rate is scalable by simply increasing the electrode area, making the process suitable for industrial applications.<br/>This research has far-reaching implications. It not only addresses the immediate problem of recycling perovskite solar cells for a circular economy but also offers a viable solution to the broader issue of lead waste management. By converting contaminated lead into a valuable material for efficient perovskite solar cell fabrication, we can potentially eliminate both current and future concerns related to lead waste.