MXene Derived Composites For Solar Steam And Hydrogen Production

Interfacial heating-based solar water evaporation technology can effectively concentrate thermal energy at the interface of air and water,efficiently and intensively heat the thin layer of water at the interface,and form temperature and potential energy disparities to accelerate matrix water transport and water evaporation,dramatically enhancing solar-vapor conversion efficiency.With the evolution of scientific,solar photothermal-photocatalytic investigations have been progressively gaining the emphasis of investigators in the field of energy and catalysis.Photothermal-photocatalysis has been based on the synergy between photochemical and thermochemical reaction pathways to achieve efficient conversion of liquid water-steam-hydrogen,improving catalytic activity and modulating catalytic reaction pathways and selectivity.Exploring the photothermal synergy has illuminating implications for improving photothermal-photocatalytic performance and studying its mechanism.In this thesis,by elaborating and solving the key problems of light capture,thermal management and stability in the photothermal materials of evaporative devices,we prepared titanium carbide（MXene）-based composite photothermal conversion materials through rational utilization and design,and explored their light absorption properties,photothermal conversion and photothermal-photocatalytic performance.The main research results are as follows:1.Bifunctional two-dimensional Bi VO₄/Ti₃C₂nanocapsules for solar steam and synergistic hydrogen production.A new solar interface evaporator with a layered structure（TC/BV@NRL）has been designed and prepared by adopting a titanium carbide/bismuth vanadate composite photothermal material as the photothermal conversion layer（Ti₃C₂/Bi VO₄）and a natural rubber aerogel material base material as the water transport layer and thermal insulation layer.This two-dimensional material,MXene,has a light absorption rate of 95%（200-2500 nm）,which gives excellent light absorption performance of the photothermal conversion layer.The three-dimensional porous structure,excellent hydrophilicity,acid and alkali resistance and strong mechanical strength of natural rubber aerogel（NRL）enable the steady long-term delivery of moisture to the evaporating surface through the capillary effect.At addition,the low thermal conductivity of NRL(0.1442 W m^-1K^-1in the humid state)ensures excellent thermal insulation of the entire solar evaporation device to reduce heat loss during evaporation.At a light intensity of 1 k W m^-2,the TC/BV@NRL thermal vaporizer delivers a high-level vaporization rate of 2.015 kg m^-2h^-1,and the TC/BV complementary heterostructure produces 9.39μmol of photocatalytic hydrogen after 4 h of reaction,with a photothermal conversion efficiency of 93.4%.This work has presented a fascinating approach to the engineering and manufacturing of sustainable photovoltaics steam generator for the purification of water and and solar energy-driven photocatalytic hydrogen production.2.Three-dimensional Ti₃C₂/Mo S₂-Zn In₂S₄photothermal biphasic system for solar steam and hydrogen production.An efficient biphasic photothermal-photocatalytic evaporation system has been prepared employing Ti₃C₂/Mo S₂-Zn In₂S₄as the photothermal-photocatalyst and natural silk water with excellent hydrophilic and thermal storage properties as the water channel and thermal insulation layer.ue to the tight stacking of Mo S₂and Zn In₂S₄to constitute s-type heterojunctions,which could enhance the charge transfer and accelerate the separation of photosynthetic electron and cavity pairs.The high-permeability and stratified nanostructure of MXene as the carrier of charge transport layer dramatically inhibits photoinduced reassociation of carriers,facilitates the transition of photogenerated electrons to the photocatalyst surface,and remarkably improves the efficiency of photothermal synergistic photocatalytic hydrogen production.The full-spectrum absorption of the photothermal co-catalyst material MXene/Mo S₂,which provides the required thermal hank for the reaction,thermodynamically and kinetically enhances the solar water evaporation rate and the photocatalytic hydrogen production rate.The maximum hydrogen production efficiency of the composite photothermal-photocatalyst under synergistic effect can reach 13.945 mmol g^-1h^-1at a light intensity of 1 k W m^-2.The hydrogen production efficiency of TM-ZIS@NASs natural silk aerogel（NSAs）can reach 374.196 umol g^-1h^-1cm^-2,corresponding to a water vaporization efficiency of 2.578 kg m^-2h^-1,and the photosynthetic transformation efficiency can reach 94.176%.The photothermal-photocatalytic biphasic system has good adaptability and hydrogen production potential,which provides a new solution for the realization of solar desalination and solar photothermal-photocatalytic hydrogen precipitation biphasic combined system.This combined design of TM-ZIS@NSAs based photothermal evaporation and photocatalytic hydrogen production unit is a synergistic and promising strategy.The monolithic design provides a new and novel approach to solar energy acquisition and transformation through the rational application of solar-driven interfacial water evaporation technology to generate renewable water and clean energy.