Highly Efficient Solar-Driven Carbon Dioxide Reduction on Molybdenum Disulfide Catalyst Using Choline Chloride-Based Electrolyte

Conversion of CO ₂ to energy-rich chemicals using renewable energy is of much interest to close the anthropogenic carbon cycle. However, the current photoelectrochemical systems are still far from being practically feasible. Here the successful demonstration of a continuous, energy efficient, and scalable solar-driven CO ₂ reduction process based on earth-abundant molybdenum disulfide (MoS ₂ ) catalyst, which works in synergy with an inexpensive hybrid electrolyte of choline chloride (a common food additive for livestock) and potassium hydroxide (KOH) is reported. The CO ₂ saturated hybrid electrolyte utilized in this study also acts as a buffer solution (pH ≈ 7.6) to adjust pH during the reactions. This study reveals that this system can efficiently convert CO ₂ to CO with solar-to-fuel and catalytic conversion efficiencies of 23% and 83%, respectively. Using density functional theory calculations, a new reaction mechanism in which the water molecules near the MoS ₂ cathode act as proton donors to facilitate the CO ₂ reduction process by MoS ₂ catalyst is proposed. This demonstration of a continuous, cost-effective, and energy efficient solar driven CO ₂ conversion process is a key step toward the industrialization of this technology.