Enhanced H₂O₂ Upcycling into Hydroxyl Radicals with GO/Ni:FeOOH-Coated Silicon Nanowire Photocatalysts for Wastewater Treatment

Abstract

There remains continued interest in improving the advanced water oxidation process [e.g., ultraviolet (UV)/hydrogen peroxide (H2O2)] for more efficient and environmentally friendly wastewater treatment. Here, we report the design, fabrication, and performance of graphene oxide (GO, on top)/nickel-doped iron oxyhydroxide (Ni:FeOOH, shell)/silicon nanowires (SiNWs, core) as a new multifunctional photocatalyst for the degradation of common pollutants like polystyrene and methylene blue through enhancing the hydroxyl radical (•OH) production rate of the UV/H2O2 system. The photocatalyst combines the advantages of a large surface area and light absorption characteristics of SiNWs with heterogeneous photo-Fenton active Ni:FeOOH and photocatalytically active/charge separator GO. In addition, the built-in electric field of GO/Ni:FeOOH/SiNWs facilitates the charge separation of electrons to GO and holes to Ni:FeOOH, thus boosting the photocatalytic performance. Our photocatalyst increases the •OH yield by 5.7 times compared with that of a blank H2O2 solution sample and also extends the light absorption spectrum to include visible light irradiation.

Green and sustainable in situ water treatment: a review of noble-free catalysts for electrochemical oxygen reduction to hydrogen peroxide

“…In addition, ˙OH are highly reactive and can effectively degrade a wide range of organic pollutants, they do not have selectivity. 18 This means they can also react with natural organic matter and inorganic ions present in wastewater, which leads to the excessive consumption of ˙OH and increases the cost of water treatment.…”

“…15,16 In comparison with other reactive oxygen species, the hydroxyl radical (˙OH) is distinguished by its high oxidation potential, which endows it with a wide range of applicability due to its non-reliance on specific functional groups or molecular structures. 17,18 Additionally, hydrogen peroxide (H 2 O 2 ), utilized in the generation of ˙OH, is capable of undergoing complete decomposition, thereby negating any potential environmental threat. At present, commercial high-concentration H 2 O 2 (30–70 wt%) is employed in AOPs.…”

Efficient Proton Transfer and Charge Separation within Covalent Organic Frameworks via Hydrogen-Bonding Network to Boost H2O2 Photosynthesis

“…Many investigations have been attempted to improve the separation and transfer of photogenerated charges so as to enhance photocatalytic performance. − Unfortunately, the 2e – ORR (O 2 + 2H + + 2e – → H 2 O 2 ) is a proton-coupled electron transfer (PCET) reaction. , In addition to efficient electron transfer, the rapid conduction of protons should also contribute heavily to the efficient production of H 2 O 2 , which has been ignored in the photocatalytic 2e – ORR.…”

Electrocatalytic Generation of Singlet Oxygen via ROS-Mediated Redox Chain Reaction for Efficient Disinfection

“…Harmful microorganisms in environmental water have been posing risks to ecosystems and human health. − Advanced oxidation processes (AOPs) can effectively inactivate harmful microorganisms by producing reactive oxygen species (ROS), such as hydroxyl radicals ( • OH), singlet oxygen ( 1 O 2 ), and superoxide radicals ( • O 2 – ). − Compared to short-lived and nonselective • OH, the relatively stable 1 O 2 has unoccupied π* orbitals and a mild oxidizing ability, making it highly selective toward electron-rich substances such as drugs, unsaturated organics, and microbial pathogens. , Consequently, 1 O 2 -targeted reactions showed a high potential for the inactivation of harmful microorganisms in wastewater treatment such as in industrial or medical fields. − …”