High-entropy-assisted platinum single atoms for photothermal green syngas production with high CO2 utilization efficiency†

The reverse water gas shift reaction (RWGS) can convert CO₂ into green syngas, but its efficiency is limited by a low CO₂ utilization rate. High temperatures can promote CO₂ conversion rates in RWGS; however, most catalysts are unstable and inactive at high temperatures. In this study, we synthesized a two-dimensional high-entropy oxide to stabilize Pt single atoms (Pt@CeYLaScZrO_x) for high-temperature RWGS. Compared to the 494 mmol g⁻¹ h⁻¹ CO production rate of Pt@ZrO₂ at 600 °C in RWGS, Pt@CeYLaScZrO_x exhibited a significantly higher CO production rate of 1350 mmol g⁻¹ h⁻¹, a CO₂ conversion rate of 55% and stable operation for 72 h at 600 °C, exhibiting unparalleled high-temperature stability. Various characterizations confirmed the robustness of Pt single atoms in Pt@CeYLaScZrO_x during high-temperature RWGS, and theoretical calculations indicated that the high-entropy property of CeYLaScZrO_x contributed to the thermodynamically stable state of Pt single atoms, preventing Pt sintering. As a result, Pt@CeYLaScZrO_x could operate in photothermal RWGS under 3.2 kW m⁻² intensity of sunlight irradiation, achieving a CO generation rate of ∼13.6 ml min⁻¹, a CO₂ conversion rate of 45% and stable operation for 100 h. This work provides a universal solution for preparing noble metal single-atom catalysts that remain stable under hydrogen-rich and high-temperature environments.