Solar CO₂ splitting coupling with PV, photon-enhanced thermionic emission cell and SOEC for efficient full-spectrum utilization in a wide temperature range

CO₂ splitting driven by solar energy is a clean and promising approach for addressing the issue of CO₂ emission and approaching the dual-carbon target. Here, a high-efficient solar CO₂ electrolysis system containing photovoltaic (PV) cell, photon-enhanced thermionic emission cell (PETE), and solid oxide electrolysis cell (SOEC) is proposed. CO₂ serves as cool fluid to decrease the temperature of PV cells for the enhancement of PV efficiency, and the heated CO₂ by PV cells and PETE is fed into SOEC at a high temperature to decrease the Gibbs free energy utilized in electrolysis. The combination of PV cell and PETE can enlarge the temperature range for full solar spectrum utilization. Compared to H²O splitting in SOEC, CO₂ splitting can convert more thermal energy with relatively low energy level into high-energy-level chemical energy. The system can reach the energy efficiency, exergy efficiency, and solar-to-fuel efficiency of 73.5%, 48.0%, and 33.3%, respectively. This research sheds light on high-efficient solar CO₂ splitting system design with full solar spectrum utilization in a wide temperature range.