Preparation of the W18O49/g-C3N4 heterojunction catalyst with full-spectrum-driven photocatalytic N2 photofixation ability from the UV to near infrared region

Abstract

As we all know, more than half of the solar spectrum is near infrared (NIR) light. However, NIR light is seldom utilized in photocatalytic reactions. In this work, the W₁₈O₄₉/g-C₃N₄ heterojunction catalyst is prepared and used for full-spectrum-driven N₂ photofixation from the UV to the NIR region for the first time. X-ray diffraction, N₂ adsorption, UV-Vis-NIR spectroscopy, scanning electron microscopy, transmission electron microscopy, photoluminescence, X-ray photoelectron spectroscopy and electrochemical impedance spectra were used to characterize the prepared catalysts. The result indicates that the as-prepared W₁₈O₄₉/g-C₃N₄ heterojunction catalysts display much higher N₂ photofixation performance than individual W₁₈O₄₉ or g-C₃N₄, which should be due to the improved separation rate of electron–hole pairs. g-C₃N₄ is the active component in the catalyst for N₂ photofixation. W₁₈O₄₉ plays the role of a light absorber in the full-spectrum to form more photogenerated electrons for recombining the holes in g-C₃N₄ through the “Z-scheme” mechanism. A possible electron transfer route is proposed.