New Application of Z-Scheme Ag₃PO₄/g-C₃N₄Composite in Converting CO₂to Fuel

TLDR

The study investigates the photocatalytic conversion of CO₂ to fuels using a novel Ag₃PO₄/g‑C₃N₄ composite under simulated sunlight. The composite was prepared by in‑situ deposition and characterized by BET, XRD, FT‑IR, SEM, TEM, XPS, UV‑vis DRS, PL, and electrochemical methods. The Ag₃PO₄/g‑C₃N₄ heterojunction, featuring a Z‑scheme charge‑transfer mechanism, markedly improves CO₂ photoreduction, achieving a 57.5 µmol h⁻¹ g_cat⁻¹ rate—over six times that of g‑C₃N₄ and ten times that of P25—and demonstrates simultaneous environmental remediation and fuel production.

Abstract

This research was designed for the first time to investigate the activities of photocatalytic composite, Ag3PO4/g-C3N4, in converting CO2 to fuels under simulated sunlight irradiation. The composite was synthesized using a simple in situ deposition method and characterized by various techniques including Brunauer–Emmett–Teller method (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and an electrochemical method. Thorough investigation indicated that the composite consisted of Ag3PO4, Ag, and g-C3N4. The introduction of Ag3PO4 on g-C3N4 promoted its light absorption performance. However, more significant was the formation of heterojunction structure between Ag3PO4 and g-C3N4, which efficiently promoted the separation of electron–hole pairs by a Z-scheme mechanism and ultimately enhanced the photocatalytic CO2 reduction performance of the Ag3PO4/g-C3N4. The optimal Ag3PO4/g-C3N4 photocatalyst showed a CO2 conversion rate of 57.5 μmol·h–1·gcat–1, which was 6.1 and 10.4 times higher than those of g-C3N4 and P25, respectively, under simulated sunlight irradiation. The work found a new application of the photocatalyst, Ag3PO4/g-C3N4, in simultaneous environmental protection and energy production.