Advanced 2D materials support superior solar device fabrication

In a study submitted to the journal Nano energya variety of transition metal dichalcogenide and nitrogen-rich nitride heterostructures for solar water evaporation have been created by partially crystalline conversion, namely WS2-W2NOT3MoS2-Mo5NOT6and NbS2-Nb4NOT5.

Study: Advanced 2D-2D heterostructures of transition metal dichalcogenides and nitrogen-rich nitrides for solar water production. Image Credit: Zentinel/Shutterstock.com

Due to their distinct physical and chemical characteristics, nanoscale particles of 2D transition metal dichalcogenides and higher metal nitrides have shown great prospects for use in optoelectronics and energy storage applications.

Tackling the water crisis

With industrial and societal growth, scarcity of fresh water began to pose a major risk to daily life. Substantial efforts have been made to investigate improved methods for creating potable water, such as reverse osmosis (RO), membrane distillation (MD), thermal distillation by heating bulk water, and electrodialysis.

Energy from the sun has been studied for use in producing clean water using a solar-to-thermal (light-to-heat) transformation approach, which derives thermal energy from absorbed solar energy for evaporation of the water. Photothermal substances – which serve as solar absorbers – have a wide light absorption range (280-2500 nm), a large absorption strength and a minimum reflectance or transmission which is necessary for very high heat production. effective in a sunlight-powered evaporative setup.

Limitation of two-dimensional transition metal dichalcogenides

Due to their unique physicochemical characteristics, 2D materials such as transition metal dichalcogenides (TMDs) and hexagonal boron nitride (h-BN) have been extensively researched and implemented in the fields of photothermal transformation, energy extraction and water vaporization since the emergence of graphene. . However, common TMD substances with bandgaps around 1–2.5 eV capture the absorption of short-wave solar radiation, limiting their photothermal absorption capabilities and transformation performance.

Transition metal carbides/nitrides could be the key

Transition metal carbides/nitrides (MXene-TMC/TMN) have encouraging potential implementation in photo-thermal transformation due to their unique ability to absorb EM waves and localized surface plasmon phenomenon , leading to broadband light absorption (ultraviolet-visible-infrared) and excellent photo-thermal transformation efficiency.

When the metal atoms are in higher oxidation states, the respective metal nitrides are expected to generate nitrogen-rich transition metal nitrides (NR-TMNs). These qualities can cause certain nitrides, such as NR-Mo5NOT6to acquire metallic characteristics, leading to increased electro-catalysis efficiency unlike nitrogen-poor nitrides.

Accordingly, the creation of transition metal dichalcogenide NRTMN heterostructures would offer a reliable method to broaden the absorbance range of the spectrum and increase the strength of photo-absorption to achieve highly efficient photo-thermal functionality. More importantly, due to the enhanced oxidation procedure, especially the sulphate radical procedure or the semiconductor photocatalysis function, these heterostructured substances have a good ability to destroy biological contaminants in wastewater. Configurable fabrication of TMDs-NR-TMNs heterostructures has not yet been achieved.

Synthesis and structural evaluation

In this study, researchers investigated 2D-2D TMDs-NR-TMNs heterostructures by partial crystal transition. This method yielded a number of TMDs-NR-TMNs nanofilms, including WS2-W2NOT3MoS2-Mo5NOT6and NbS2-Nb4NOT5. The anatomy of the material was studied using the scanning electron microscopy (SEM) technique.

All WS anatomy2-W2NOT3MoS2-Mo5NOT6and NbS2-Nb4NOT5 specimens exhibited nano-film characteristics, which were distinct from bulk predecessors of WS2MoS2and NbS2. The microscopic architectures were studied by transmission electron microscopy (TEM). TEM findings verified that TMDs-RN-TMN heterostructures exhibited nanofilm architectures.

Main results of the study

Researchers created a range of 2D-2D TMDs-NR-TMNs heterostructures for highly efficient sunlight-powered water vaporization, namely WS2-W2NOT3MoS2-Mo5NOT6and NbS2-Nb4NOT5. The spectral absorption capacity of these heterostructured nano-films was greater than 92%. They were chemically stable in a variety of environments, including water, 1M acid solution, and 1M alkaline solution.

More importantly, due to their broadband spectral absorbance, heat surface localization, and lower heat losses than bulk water, MoS2-Mo5NOT6/MF systems have demonstrated remarkable vaporization rate and efficiency. Additionally, MoS2-Mo5NOT6/melamine systems have demonstrated useful applicability in seawater desalination processes. The current synthetic technique is believed to be capable of producing a diverse range of 2D-2D hetero-structured materials like TMD-carbides , TMD-carbonitrides and borides, as well as an abundance of high quality compounds for energy purposes such as solar energy capture.

Reference

Wang, L., Liu, D., Jiang, L., Ma, Y., Yang, G., Qian, Y. & Lei, W. (2022). Advanced 2D-2D heterostructures of transition metal dichalcogenides and nitrogen-rich nitrides for solar water production. Nano energy. Available at: https://www.sciencedirect.com/science/article/pii/S2211285522002737?via%3Dihub

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