Electrochemical reduction of CO₂ into valuable chemicals like formic acid or formate is an emerging carbon conversion strategy. Tin-based catalysts are among the most effective materials for this conversion due to their favorable selectivity toward formate production. However, conventional tin catalysts often exhibit low current densities and cannot process CO₂ at rates suitable for industrial operations. They also require high overpotentials, leading to increased energy consumption and reduced efficiency. Further, these catalysts tend to have poor long-term stability, degrading over time, and necessitating frequent replacement or regeneration. They can be difficult to scale up for industrial use, further limiting their commercial viability. These challenges highlight the need for developing new catalyst materials and synthesis methods that can achieve high activity and stability at lower energy costs, are tolerant to common contaminants, and are amenable to large-scale production.

NETL’s invention presents a sulfur-doped SnO₂ catalyst for converting CO₂ into formic acid or formate, addressing the shortcomings of traditional tin-based catalysts. The catalyst is synthesized through a simple, scalable process involving the thermal treatment of SnO₂ with sulfur under inert conditions. This method enhances CO₂ conversion efficiency by 4-6 times compared to undoped SnO₂, achieving nearly 90% Faradaic efficiency and maintaining performance over extended periods. The catalyst demonstrates significant stability over extended operation times and inherent tolerance to sulfur contaminants in industrial CO₂ streams, distinguishing it from existing approaches that suffer from degradation under similar conditions. This advancement enables efficient, carbon-negative chemical production on an industrial scale using excess renewable energy, with reduced power requirements and improved energy efficiency.