Enhancement of H2O2 generation rate in porphyrin photocatalysts via crystal facets regulation to create strong internal electric field

Three TCPP porphyrin-based nanosheet photocatalysts with exposed (400), (022), and (020) planes were synthesized using a dissolution-recrystallization method in a mixture of water and tetrahydrofuran (THF), methanol (MeOH), and ethylene glycol (EG). The TCPP photocatalyst with the exposed (400) surface exhibited the highest H₂O₂ production rate of 29.33 mmol L⁻¹ h⁻¹ g⁻¹ from only H₂O and O₂, surpassing the rates observed for ones with exposed (022) and (020) surfaces by factors of 2.7 and 4.1, respectively, and 1.3 times as that of the reported TCPP prepared by a base/acid self-assembling method. This enhancement can be attributed to the strong internal electric field and high carboxyl group content on the (400) surface, which hindered rapid charge recombination and facilitated challenging water oxidation. Hence, successful manipulation of porphyrin exposure to robust IEF planes enhances the photocatalytic activity of the system and provides valuable insights for the design and development of more efficient organic photocatalysts.