EPR investigations of polymeric and H2O2-modified C3N4-based photocatalysts

Delocalization of π‐Electron in Graphitic Carbon Nitride to Promote its Photocatalytic Activity for Hydrogen Evolution

“…Given that unpaired electrons play a major impact on the photocatalytic performance, electron paramagnetic resonance (EPR) of the as‐prepared samples was measured to further inspect the free electrons. As indicated in Figure a, all samples possess single Lorentzian lines, originated from carbon atoms of the aromatic rings in the triazine unit . Apparently, UCN‐AB and UCN‐APy show a highly enhanced EPR signal in comparison with UCN both in the dark and under the light, implying that high delocalization of the extensive conjugated system in UCN‐AB or UCN‐APy smartly accelerates the separation rate of electrons and holes.…”

“…As indicated in Figure 5a, all samples possess single Lorentzian lines, originated from carbon atoms of the aromatic rings in the triazine unit. [41,42] Apparently, UCN-AB and UCN-APy show a highly enhanced EPR signal in comparison with UCN both in the dark and under the light, implying that high delocalization of the extensive conjugated system in UCN-AB or UCN-APy smartly accelerates the separation rate of electrons and holes. Moreover, UCN-APy possesses the strongest EPR signal in the dark and under visible light irradiation, standing for the highest concentration of unpaired electrons which is ascribed to the N-atom of pyridine.…”

Photobase effect for just-in-time delivery in photocatalytic hydrogen generation

“…These species can undergo further photolysis, recovering the heptazine and releasing hydrogen radicals that further react to form molecular H 2 . In corroborating evidence, Electron Paramagnetic Resonance (EPR) experiments show that a long-lived radical forms in cyanamide-functionalized heptazine-based g-CN upon illumination that can be later, under dark conditions, used to produce H 2 [28][29][30] . It has been observed that protonation of the g-CN structure in acidic media increases the H 2 evolution rate [31][32][33] .…”

Understanding the bactericidal mechanism of Cu(OH)2 nanorods in water through Mg-substitution: high production of toxic hydroxyl radicals by non-soluble particles

“…5a). Each experimental EPR spectrum can be satisfactorily fitted with two superimposed signals characterized by the spin-Hamiltonian parameters typical for two DMPOadducts of oxygen-centered radicals, namely DMPO-O 54,55 (Fig. 5a).…”

“…S3 in Section S5, ESI †). Each experimental EPR spectrum can be satisfactorily fitted with three superimposed signals: (i) four-line signal of DMPO-OH spin adduct (a N = 1.507 AE 0.004 mT, a b H = 1.477 AE 0.007 mT, g = 2.0057), 54,55 (ii) six-line signal with parameters typical for DMPO-adduct with carbon-centered radical (a N = 1.602 AE 0.005 mT, a b H = 2.331 AE 0.008 mT, g = 2.0055) and (iii) six-line signal compatible with DMPO-C(O)R spin adduct (a N = 1.493 AE 0.004 mT, a b H = 1.843 AE 0.004 mT, g = 2.0059). 56 As shown in Fig.…”