A novel Fenton-like catalyst of Ag3PO4/g-C3N4: Its performance and mechanism for tetracycline hydrochloride degradation in dark

Generation of singlet oxygen over CeO2/K,Na-codoped g-C3N4 for tetracycline hydrochloride degradation over a wide pH range

“…The (Ce 3+ ) surf reacts with H 2 O 2 to form (Ce 4+ ) surf and ˙OH radical (eqn (2)). The (Ce 4+ ) surf reacts with H 2 O 2 to form (Ce 3+ ) surf and ˙HO 2 radical just like Fenton processes reported in the literature 13,28 (eqn (3)). Then, (Ce 3+ ) surf reacts with the formed ˙HO 2 radical to generate O 2 (eqn (4)).…”

“…4c illustrates the high-resolution XPS spectra of C 1s for CN and CeO 2 /CN, which could be deconvoluted into three peaks corresponding to sp 2 C–C bonds of the graphic carbon (C I , 284.8 eV), C-NH x ( x = 1, 2) on the edges of heptazine units (C II , 286.3–285.9 eV), sp 2 -bonded carbon (N–CN) (C III , 288.2–288.5 eV), respectively. 28,64,65 The binding energies of C II and C III for the CeO 2 /CN sample show slight shifts ( ca. −0.4 for C II , +0.3 eV for C III , see Table S1†) compared with those of CN, also confirming the interaction between CeO 2 and CN.…”

“…Three fitting peaks located at 398.6–398.5, 399.7–399.6 and 401.2–401.0 eV can be ascribed to the N atoms in C–NC (N I ), N–(C) 3 (N II ), and N–H side groups (N III ), respectively. 28 The fitting peak located at 406.8–404.7 eV (N IV ) arises from the π-electrons excitation. 65,66 Compared with CN, all the peaks for N 1s in CeO 2 /CN become much weaker owing to the lower N content in composite, and their binding energies also present a positive shift (0.1 eV for N I , 0.1 eV for N II , 0.2 eV for N III , 2.1 eV for N IV , see Table S1†) than those of CN.…”

“…Then, (Ce 3+ ) surf reacts with the formed ˙HO 2 radical to generate O 2 (eqn (4)). The generated ˙HO 2 radicals also can be decomposed into ˙O 2 − radicals 7,28 (eqn(5)). The generated and dissolved O 2 in water can react with the electrons (from defects in CeO 2 or the migration from CN, confirmed by EPR and XPS) to form ˙O 2 − radical (eqn (6)).…”

“…In addition, most heterogeneous Fenton-like catalysts exhibit good oxidation performance generally under acid conditions/or with the help of light irradiation/electrical field, which restricts their applications. 8–10,12–15,25–28 To overcome these shortages, one of the strategies is to develop novel highly-effective Fenton-like catalysts to activate H 2 O 2 to generate long-life-time ROS (such as 1 O 2 ).…”