Lignin-Supported Heterogeneous Photocatalyst for the Direct Generation of H₂O₂ from Seawater

Abstract

The development of smart and sustainable photocatalysts is in high priority for the synthesis of H2O2 because the global demand for H2O2 is sharply rising. Currently, the global market share for H2O2 is around 4 billion US$ and is expected to grow by about 5.2 billion US$ by 2026. Traditional synthesis of H2O2 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 H2O2 directly from seawater under air. In fact, in the presence of this catalyst, we have been able to achieve 4085 μM of H2O2. Expediently, the catalyst has shown longer durability and can be recycled more than five times to generate H2O2 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.

Supported nanostructured photocatalysts: the role of support-photocatalyst interactions

“…Once suitable supports are used, the supported nanostructured photocatalyst systems offer several advantages, including better dispersion and reduced agglomeration, enhanced surface area, easy handling and recovery, and improved recyclability of the photocatalyst particles [30,33]. Moreover, as discussed in the following sections, the supported photocatalytic materials' optical, thermal, and photocatalytic properties can be modified, and often improved, owing to different support-photocatalyst interactions [27,29,[38][39][40][41]. While the improved physiochemical properties of supported nanostructured photocatalyst arising from support-photocatalysts interactions have been the subject of many studies [12,27,29,38,[40][41][42], comprehensive reviews highlighting the important supportphotocatalysts interactions are uncommon in published literature.…”

Electrochemical Depolymerization of Lignin in a Biomass‐based Solvent**

“…[1][2][3] In this context, lignocellulose biorefinery has been recognized as a potential candidate to replace petroleum refinery, while being a carbon-neutral and non-food feedstock. [4][5][6][7] Lignocellulosic biomass consists mainly of cellulose, lignin, hemicelluloses, and extractives. Comprising three different phenylpropane monomer units (monolignols), lignin is the second most abundant macromolecule on earth, while its annual production is estimated in the range of 100 million tons.…”

“…Therefore, the sustainable production of fuels and valuable chemicals based on the efficient use of renewable resources has become an urgent matter [1–3] . In this context, lignocellulose biorefinery has been recognized as a potential candidate to replace petroleum refinery, while being a carbon‐neutral and non‐food feedstock [4–7] . Lignocellulosic biomass consists mainly of cellulose, lignin, hemicelluloses, and extractives.…”

Nanostructured α‐Fe2O3 Photoelectrodes with Transparent and Conducting Sb‐Doped SnO2 Films Deposited by Atomic Layer Deposition

“…However, these fabrication techniques are not suitable for complete conformal coating of porous media and/or nanostructured substrates containing trenches and holes. The fabrication of TCO layers with the geometry of a higher roughness factor has significant importance, especially in photoelectrochemical (PEC) applications, [7] which require large surface area along with highly conductive and transparent current collectors. There have been some attempts to construct such transparent conducting nanostructures using template-assisted solution processes, [8,9] direct growth of nanorod arrays [10,11] or even chemical etching of dense TCO films.…”