Fabricating Amorphous g-C₃N₄/ZrO₂ Photocatalysts by One-Step Pyrolysis for Solar-Driven Ambient Ammonia Synthesis

Solar-driven nitrogen fixation remains a significant challenge. Graphitic carbon nitride (g-C₃N₄) is considered as a promising visible light photocatalyst. However, the photocatalytic performance of g-C₃N₄ is unsatisfactory because of the random transfer of charge carriers in the plane and the low activation efficiency of the reactants. Herein, amorphous ZrO₂ was used as a robust cocatalyst of g-C₃N₄ to increase the NH₃ production activity. The g-C₃N₄/ZrO₂ lamellar composites were constructed by a simple one-step pyrolysis of the deep eutectic solvent ZrOCl₂·8H₂O/urea. The optimum NH₄⁺ yield could reach as high as 1446 μmol·L^-1·h^-1 at 30 wt % ZrO₂ in the g-C₃N₄/ZrO₂ composites, with an apparent quantum efficiency over 2.14% at 400 nm. It is 7.9 times that of pristine g-C₃N₄ and 27.5 times that of ZrO₂. The introduction of amorphous ZrO₂ restrained the hydrogen generation, and the amorphous ZrO₂ and g-C₃N₄ together contribute to the rapid photoproduced electron transfer of less electron-hole pair recombination.