Abstract:

Fe₂O₃/g-C₃N₅ photocatalyst was prepared by solvothermal method, and its performance in methane removal from coal mine gas was studied. X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, ultraviolet-visible diffuse reflectance spectroscopy （UV-vis DRS）, photoluminescence （PL）, transient photocurrent spectroscopy （TPC）, electrochemical impedance spectroscopy （EIS） and electron spin resonance spectroscopy （ESR） were used to characterize the crystal structure, characteristic absorption bands, spectral absorption, photoelectron-hole recombination, photoelectrochemical properties and active groups of the photocatalyst. The results showed that, under simulated sunlight irradiation for 180 min, the Fe₂O₃/g-C₃N₅ photocatalyst had removed 96.8% of CH₄ （the initial volume fraction of CH₄ was 18%）, and the removal efficiency of CH₄ could still reach 95.8% after 5 cycles, indicative of good photocatalytic activity and stability. That was due to the construction of Z-scheme heterojunction between Fe₂O₃ and g-C₃N₅, which effectively promoted the photoelectron-hole separation, broadened the spectral absorption range, and promoted charge transfer. CH₄ was attacked by h⁺ to generate ·CH₃, which was further oxidized by ·O₂^- and ·OH to achieve degradation and removal. This work could provide a theoretical basis for photocatalytic removal of CH₄ in coal mine gas.

Key words: nitrogen-rich carbon nitride, photocatalyst, heterojunction, gas, methane