2D Higher‐Metal Nitride Nanosheets for Solar Steam Generation

Abstract

excellent electromagnetic wave absorption capacity and a localized surface plasmon effect, resulting in broadband light (UVvis-Infrared) absorption and excellent photothermal conversion efficiency. [8][9][10][11][12] Specifically, plasmonic TMN materials have displayed high melting points, excellent thermal and chemical stabilities, and are less expensive than noble metals such as Au. [13] Recently, group 4 TMNs (65% of HfN, 58% of ZrN, and 49% of TiN) exhibited higher photothermal transduction efficiencies than that of commercially Au (43%) samples because of their strong localized surface plasmon resonance effects. [14,15] However, most of these TMN compounds are usually formed from non-or sub-stoichiometric compositions and contain low nitrogen content. [16] Specifically, when the metallic atoms are in higher oxidation states, their corresponding metal nitride compounds are expected to form higher-metal (HM) nitrogen-rich (Nitrogen:Metal ratio >1) nitrides. These characteristics can result in some nitrides, such as HM-Mo 5 N 6 , posessing metallic properties resulting in improved electrocatalytic performance compared to nitrogen-poor nitrides. This can be attributed to the more complicated electron orbital hybridization state in Mo 5 N 6 compared to MoN. [17] For instance, the d band center positions of HM-Mo 5 N 6 and MoN are −1.96 and −2.28 eV. Therefore, the high valence state of Mo atoms in HM-Mo 5 N 6 and strong plasmon effect result in better catalytic activity and demonstrate great potential for solar-driven water generation. Alternatively, other HM nitrides, such as Ta 3 N 5 , demonstrate semiconductivity, which is advantageous for applications such as photoelectrochemical water splitting. [18] Furthermore, due to their higher oxidation states, HM-nitrides exhibit excellent corrosion resistance and high conductivity resulting in electrochemical catalytic behavior under harsh environments such as extremes of pH. [17,19] To date, chemical vapor deposition (CVD) has been explored to synthesize graphene, transition metal dichalcogenides (TMDs) hexagonal boron nitride (h-BN), and has also been used to obtain Mo 2 C, MoN, and Mo 5 N 6 nanosheets through the selection of specific precursors. [20][21][22][23][24][25] Furthermore, other researchers have also obtained metal nitrides via either the salt-template-assisted or atomic substitution methods under an ammonia atmosphere. [26][27][28][29][30] Although there has been Higher-metal (HM) nitrides are a fascinating family of materials being increasingly researched due to their unique physical and chemical properties. However, few focus on investigating their application in a solar steam generation because the controllable and large-scale synthesis of these materials remains a significant challenge. Herein, it is reported that higher-metal molybdenum nitride nanosheets (HM-Mo 5 N 6 ) can be produced at the gramscale using amine-functionalized MoS 2 as precursor. The first-principles calculation confirms amine-functionalized MoS 2 nanosheet effectively lengthens...

Decreasing the Energy of Evaporation Using Interfacial Water: Is This Useful for Solar Evaporation Efficiency?

“…Radiation from the sun heats the evaporation apparatus. At a constant external pressure, the heat, Q, required to evaporate bulk water is equal to the enthalpy of vaporization of bulk water (1) where H V is the enthalpy of water vapor, and H L is the enthalpy of the bulk liquid water. In this manuscript, all enthalpies refer to the molar enthalpy, and we note that the enthalpies depend on the pressure and the temperature.…”

“…Solar-powered evaporation is advantageous for these applications because the CO 2 output is lower than when the combustion of fossil fuels is used to supply the heat, and this has stimulated recent research to optimize solar evaporation. Two fundamental directions of enquiry have been advanced: (1) methods for absorbing the maximum energy from the sun for use in evaporation (e.g., ref ) and (2) methods for facilitating evaporation. Among the second category are methods where the energy of evaporation is reduced by evaporating interfacial water or other modified water. − Several variants of this method have been discussed, and the purpose of this brief article is to discuss the potential of this idea from a thermodynamic perspective.…”

Improved Photo‐Excited Carriers Transportation of WS2‐O‐Doped‐Graphene Heterostructures for Solar Steam Generation

“…The resistance values of 0.02 and 1.3 M Ω for saline water and purified water were recorded by a resistance measurement with a constant distance between two electrodes, indicating effective salt removal (Figure 4c). [ 49–51 ] The condensed water from the acidic and alkaline seawater also revealed a neutral pH value (Figures 4d,e). Furthermore, according to the UV–vis absorption spectra (Figure 4f), almost no characteristic absorption peak for RhB dye was detected in the purified water, indicating that the dye molecules were not carried into the collected water.…”

Sustainable Interfacial Evaporation System Based on Hierarchical MXene/Polydopamine/Magnetic Phase-Change Microcapsule Composites for Solar-Driven Seawater Desalination

“…The temperature distribution of the beaker was monitored using a Testo 875-1i infrared camera. The evaporation rate ( E r ) and evaporation efficiency (η) were calculated using eqs and , respectively E normalr ( kg m − 2 h − 1 ) = normalΔ m S × t η ( % ) = E normalr × normalΔ H normalw P × 100 % where Δ m (kg) is the mass loss of the saline water, S (m 2 ) represents the illuminated area of the evaporator, t (h) is the irradiation time, Δ H w (J g –1 ) is the water evaporation enthalpy, and P (kW m –2 ) is the illumination intensity.…”

“…The evaporation rate (E r ) and evaporation efficiency (η) were calculated using eqs 1 and 2, respectively. 22 (1) (2) where Δm (kg) is the mass loss of the saline water, S (m 2 ) represents the illuminated area of the evaporator, t (h) is the irradiation time, ΔH w (J g −1 ) is the water evaporation enthalpy, and P (kW m −2 ) is the illumination intensity. It should be noted that the hydrogen-bonding interaction between the water molecules and the hydrophilic groups of microcapsule composites distorts the intermolecular hydrogen bonds of the water, and the evaporation enthalpy of water on the sample surface is usually lower than that of pure water (2440 J g −1 at 25 °C).…”