Synergistic effect of CuO and Sr doped g-C3N4 for CO2 photoreduction into hydrocarbon fuels

This study investigates the enhancement of the CO2 photocatalytic reduction (CO2 PR) process, which plays a critical role in sustainable fuel production and alleviates the environmental greenhouse gas emissions. Overcoming the challenges posed by CO2 inertness and sluggish charge carrier kinetics is imperative for efficient CO2 PR. Herein, we explore the role of copper oxide (CuO) and strontium (Sr) nanoparticles as cocatalysts in enhancing the photocatalytic performance of graphitic carbon nitride (g-C3N4) for CO2 reduction. With an emphasis on the often-overlooked selectivity of photo-excited electrons for CO2 reduction with H2O, we find that Sr improves electrical transport characteristics and effectively extracts photo-excited electrons, resulting in an increased CH4 yield rate (0.25 mu mol g- 1h- 1) compared to CN (0.11 mu mol g- 1h- 1). However, Sr decreases CO2 reduction selectivity by accelerating H2O reduction to H2. In addition, introducing CuO in Sr-doped g-C3N4 (SrCN) further enhances CH4 yield while increasing the selectivity for CO2 reduction. The optimized 5CuO@SrCN nanocomposite exhibits a superior CH4 selectivity of 90.34 % with a yield rate of 1.87 mu mol g- 1h- 1, demonstrating the combined effects of CuO coupling and Sr doping in improving light absorption, surface reaction sites, and charge carrier transfer and separation efficiency in CO2 reduction.