【introduction】

Water shortages and energy crises are the two major challenges facing the world this century. Solving the water crisis should be based on sustainable energy. Solar water purification technology is an efficient and green water purification technology. It uses photothermal evaporation to produce water, light-induced antibacterial treatment and photocatalytic degradation of organic pollutants, and uses abundant and clean solar energy to meet the challenges of water resources. Two-dimensional nanomaterials have the advantages of large specific surface area, wide absorption spectrum, strong absorption capacity, high photothermal and photocatalytic conversion efficiency, and have attracted widespread attention in these three water purification methods. This article reviews the research progress of two-dimensional nanomaterials in photothermal evaporation, light-induced antibacterial, and photocatalysis, and proposes various strategies to improve the light absorption and light conversion efficiency of different two-dimensional nanomaterials. Challenges and prospects of nanomaterials in practical water purification. And this review focuses on green energy-driven water purification methods based on emerging two-dimensional materials.

[Achievement Profile]

Recently, Professor Zhang Huan of Shenzhen University and Professor Hu Junqing (Communications) of Shenzhen University of Technology published a review article entitled "Solar-inspired Water Purification Based on Emerging Two-dimensional Materials: Status and Challenges" on Solar RRL. This article reviews recent developments in water purification methods based on two-dimensional nanomaterials other than graphene nanomaterials, including photothermal evaporation, antibacterial, and photocatalytic degradation. Various strategies for improving light absorption and efficiency are discussed, and the challenges and prospects of two-dimensional materials in practical applications are introduced. This article reviews the research progress of water purification technology based on two-dimensional nanomaterials, points out the advantages of these unique two-dimensional materials in solar light conversion, and provides guidance for future system design.

[Picture and text guide]

Figure 1 Various 2D materials used in solar water purification strategies

Figure 2 Photothermal mechanism

(A) Plasma thermal conversion mechanism of two-dimensional metal materials;

(B) Non-radiative relaxation of two-dimensional semiconductor materials.

Figure 3 Experimental setup
(A1) An experimental device for determining light-to-heat conversion efficiency based on droplets under laser irradiation;

(A2) Thermal equilibrium of the droplet.

(B) Schematic diagram of Ti3C2 film water evaporation device.

Figure 4 Application of TMDs in the field of photothermal evaporation
(A) Manufacturing process of SWCNT-MoS2 system;

(B1) Photograph of the prepared MoS2 cotton film and (b2) SEM image;

(C1) Chemically exfoliated MoS2 having a phase change. (C2) and c3) MoS2 / bacterial nanocellulose composite aerogel;

(D) Photograph of WOx solution as oxygen vacancies increase.

Figure 5 Tellurene applications
(A) The absorption spectrum of the Te-based absorber corresponding to the solar spectrum;

(B) Plasma-like and total dielectric scattering of Te nanoparticles of different sizes.

Figure 6 Application of 2D layered alloy material
(A) Schematic diagram of light-induced electron transfer and decay with the aid of the IB state of the alloy material;

(B) 60-day stable water evaporation efficiency.

Figure 7 Self-cleaning hydrophobic MXene film against salt deposition
(A) Self-cleaning conditions for anti-salt deposition of Ti3C2-MXene;

(B) Changes in seawater evaporation over time;

(C) Different hydrophilicity of Ti3C2 MXene with different particle sizes;

(D) Long-term desalination test of MXene membrane.

Figure 8 Formation of active oxygen
Figure 9 Photo-induced antibacterial properties of TMDs
(A) Schematic diagram of FLV-MoS2 photocatalytic active oxygen generation to inactivate bacteria;

(B) Disinfection performance of Cu-MoS2, Au-MoS2 and FLV-MoS2.

Figure 10 MXenes water purification antibacterial agent
(A) Schematic of antibacterial activity;

(B) Ti3C2Tx concentration-dependent antibacterial activity (A-F: 0, 10, 20, 50, 100, 200 μg / mL). (C) Cell viability of E. coli and Bacillus subtilis.

Figure 11 Antibacterial properties of phosphene
(A) a phosphene structure;

(B) Photographs of phosphene stripped in different solvents;

(C) Top view of the phosphene structure;

(D) Dispersibility of phosphene;

(E) Colonies of E. coli (top panel) and S. aureus (bottom panel) on various materials. (F) the sterilization rate of different materials;

(G) Colonies of E. coli (top) and Staphylococcus aureus (bottom) with different concentrations of phosphene; (h) Bacterial killing rates at different concentrations of phosphene

Figure 12 Photocatalytic mechanism
Fig. 13 Photocatalytic application of MoS2
(A) Schematic diagram of photocatalytic degradation of MoS2 film;

(B) an image of the MoS2 film;

(C) HRTEM image of two-dimensional vertical structure MoS2;

(D) Atomic structure diagram of MoS2;

(E) Photocatalytic degradation of MC-LR at pH 5.8;

(F) Comparison of adsorption of different materials.

Figure 14 Photocatalytic applications of other TMDs
(A) Photocatalytic degradation of MO under ultraviolet to near-infrared light;

(B) The ability of WS2 as a catalyst to degrade RhB under near-infrared light.

Figure 15 Photocatalytic reaction of TMOs
(A-c) HR-TEM image of MoO3;

(D, e) Photodegradation of MB and RhB, respectively;

(F) Schematic diagram of photodegradation of dyes under visible light.

Figure 16 Photocatalytic application of MXenes
(A) Photocatalytic degradation rate constant (k) of TiO2 / Ti3C2 prepared under different hydrothermal conditions; (b) Schematic diagram of the charge transfer process on TiO2 / Ti3C2;

(C) Schematic diagram of ball milling Ti2CTx to form TiO2 @ C;

(D) Schematic photocatalytic behavior of TiO2 / Ti3C2 / CuO composites;

(E) Time chart of photodegradation of MO

Fig.17 Photocatalytic reaction of phosphene
(A) Photocatalytic degradation of visible light-driven RhB;

(B) Photocatalytic degradation of RhB on BP-RP heterostructure under visible light;

(C) UV-visible absorption spectrum of BP-RP heterostructure (gray) and pure red phosphorus (red);

(D) Mechanism of photocatalytic charge separation and transfer.

Fig. 18 Photocatalytic reaction of g-C3N4
(A) Schematic diagram of g-C3N4 / Ag / MoS2;

(B) Photocatalytic degradation of RhB;

(C) Transfer mechanism of photogenerated charge carriers in g-C3N4 / Ag / MoS2 photocatalyst.

【summary】

This article summarizes three different water purification strategies using clean solar energy sources: photothermal evaporation of water production, light-induced antibacterial treatment, and photocatalytic degradation of organic pollutants. It can be found that different water treatment strategies can be achieved by using different characteristics of 2D materials, such as water desalination with photothermal characteristics, sterilization with photodynamic functions, and degradation of organics with photocatalytic degradation functions . Some 2D materials have these different properties at the same time, so a 2D material can be used to achieve synergistic photo-hot water evaporation, photodynamic antibacterial and photocatalytic degradation of organic matter, thereby achieving enhanced water treatment effects.

Literature link: Solar-Inspired Water Purification Based on Emerging 2D Materials: Status and Challenges (Solar RRL, DOI: 10.1002 / solr.201900400)

Professor Zhang Huan, male, born in 1984, is a distinguished professor of Shenzhen University, director of Shenzhen Black Phosphorus Engineering Laboratory, and doctoral supervisor. Fellow of the American Optical Society, "Youqing" of the Foundation Committee, "Highly Cited Scientist (2018/2019)" of Corewell, and Guangdong Science and Technology Leading Talent. He has been engaged in research on optoelectronic devices for low-dimensional materials for a long time. He has published more than 100 papers in the first area of the Chinese Academy of Sciences, including 2 Physics Reports, 1 PNAS, 2 Science Advance, and 6 Nature Communications articles. The H factor is 85. Professor Zhang Huan is the chief editor / editor of several SCI periodicals, the secretary-general of the China Laser Youth Editorial Board, and the vice chairman of the second presidium of the National Optical Youth Academic Forum. The scientific research achievements won the second prize of the Ministry of Education‘s Natural Science Award, the China Industry-University-Research Cooperation Innovation Award, China‘s Top Ten Optics Progress, the Guangdong Dingying Science and Technology Award, the Shenzhen Youth Science and Technology Award, and the Shenzhen Natural Science Award.
Source of information: material cattle