Lignin-Supported Heterogeneous Photocatalyst for the Direct Generation of HO from Seawater.

The development of smart and sustainable photocatalysts is in high priority for the synthesis of HO because the global demand for HO is sharply rising. Currently, the global market share for HO is around 4 billion US$ and is expected to grow by about 5.2 billion US$ by 2026. Traditional synthesis of HO via the anthraquinone method is associated with the generation of substantial chemical waste as well as the requirement of a high energy input. In this respect, the oxidative transformation of pure water is a sustainable solution to meet the global demand. In fact, several photocatalysts have been developed to achieve this chemistry. However, 97% of the water on our planet is seawater, and it contains 3.0-5.0% of salts. The presence of salts in water deactivates the existing photocatalysts, and therefore, the existing photocatalysts have rarely shown reactivity toward seawater. Considering this, a sustainable heterogeneous photocatalyst, derived from hydrolysis lignin, has been developed, showing an excellent reactivity toward generating HO directly from seawater under air. In fact, in the presence of this catalyst, we have been able to achieve 4085 μM of HO. Expediently, the catalyst has shown longer durability and can be recycled more than five times to generate HO from seawater. Finally, full characterizations of this smart photocatalyst and a detailed mechanism have been proposed on the basis of the experimental evidence and multiscale/level calculations.