Construction of full-spectrum-driven Ag–g-C3N4/W18O49 heterojunction catalyst with outstanding N2 photofixation ability

Abstract

More than half of the solar spectrum is near infrared (NIR) light, which is seldom utilized in photocatalytic reactions. In this work, an Ag–g-C₃N₄/W₁₈O₄₉ 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, thermogravimetric analysis, photoluminescence, X-ray photoelectron spectroscopy and electrochemical impedance spectra were used to characterize the prepared catalysts. The result indicates that the as-prepared Ag–g-C₃N₄/W₁₈O₄₉ heterojunction catalysts display much higher N₂ photofixation performance than that of individual W₁₈O₄₉ or Ag–g-C₃N₄, which should be due to the better separation rate of electron–hole pairs and more efficient light utilization. g-C₃N₄ is the active component in the catalyst for N₂ photofixation. Ag loading promotes the separation rate of electron–hole pairs. W₁₈O₄₉ plays a role as light absorber in the full-spectrum to form more photogenerated electrons for recombining the holes in the g-C₃N₄ through “Z-scheme” mechanism. A possible electrons transfer route is proposed.