Hydrogen peroxide (H2O2) is an important chemical product, widely used in various fields of sustainable society. At present, H2O2 production mainly adopts an anthraquinone method for large-scale production. However, in the process of producing hydrogen peroxide by the anthraquinone method, it is easy to produce toxic gases and has a risk of explosion due to the use of H2 and O2. Conversely, an emerging photocatalytic technology enables H2O2 generation from H2O, O2, and the inexhaustible sunlight energy on suitable photocatalysts.
The tetrakis(4-carboxyphenyl)porphyrin photocatalyst synthesized via an alkali/acid self-assembly method has mitigated issues related to low photo-availability and the requirement for an external sacrificial agent in conventional H2O2 producing photocatalysts. Nonetheless, the H2O2 generation efficiency of self-assembled porphyrins remains constrained by the high rate of charge complexation inherent in organic photocatalysts. Therefore, the primary research focus of this study involves enhancing charge complexation through an in-depth exploration of the intrinsic relationship between the exposed crystal surface and photocatalytic activity.
Recently, a research team led by Professor Chengsi Pan of Jiangnan University (China) reported an exposed (400) surface porphyrin photocatalyst. It exhibited the highest H2O2 production rate of 29.33 mM h-1 g-1 from only H2O and O2, surpassing the rates observed for ones with the (022) and (020) surfaces exposed by a factor of 2.7 and 4.1, respectively. The enhancement can be attributed to the strong internal electric field and high carboxyl group content exhibited on the (400) surface, hindering the rapid charge recombination and facilitating the challengeable water oxidation. Successful manipulation of porphyrin exposure to the robust IEF planes not only enhances the photocatalytic activity of the system but also provides valuable insights for the design and development of more efficient organic photocatalysts. The results were published in Chinese Journal of Catalysis (https://doi.org/10.1016/S1872-2067(24)60039-2).
