Gamma irradiation-induced elemental O/N co-doping and structural reinforcement in g-C3N4 photo-electrocatalyst

Abstract

Herein, we reported a new modification of Urea-derived g-C3N4 through gamma radiation treatment (10 kGy up to 100 kGy) for enhancing the photoelectrochemical (PEC) water splitting performance. Undoubtedly, the gamma irradiation altered the morphology, crystallinity, optical absorption, chemical bonding and electronic properties of g-C3N4. The forceful ionizing radiation (gamma radiation) modified the elemental composition via co-doping of oxygen and nitrogen atoms in g-C3N4 structure. Gamma rays exposure modified the chemical bonding and electronic properties as elucidated via X-ray photoelectron spectroscopy (XPS) analysis, enhancing the photostability of the photoanode. The morphology transformed from seaweed structure to “compact” and “agglomerate” as the irradiation increased from 10 kGy up to 100 kGy, indicating improved catalytic sites, surface area as well as light absorption. However, as probed in by Raman spectroscopy, enhanced crystallinity with reinforced structure emerged significantly as observed in the (I707/I725) position. X-ray diffraction (XRD) also showed a larger crystallite sizes as the g-C3N4 samples were gamma irradiated. Moreover, post-irradiation shows a reduction in the band gap from 2.84 eV (pure g-C3N4) to 2.74 eV (radiated), respectively. All in all, the photocurrent density increased by >200 %, reaching ∼ 4.35 μA cm−2 and 8.26 μA cm−2 for the pristine and irradiated g-C3N4, respectively. Our findings express the significance of gamma irradiation for developing impressive photostable photoanodes via ionizing radiation (γ radiation).