Preparation And Investigation On Photocatalytic Performances Of LDH-based Composite Photocatalyst

Under the background of continuous consumption of fossil fuels and rising CO₂content in the atmosphere,modern human society is facing severe energy crisis and environmental problems.How to efficiently solve these issues has become the key to the sustainable development of human.Photocatalysis has showed great potential in the field of pollutant degradation,CO₂conversion,and water splitting,displaying great prospect in treating energy and environmental problems.However,the conventional and widely studied photocatalysts currently have the shortcomes of large band gap and high electron-hole recombination rate during the reaction,severely limiting the research and development of photocatalytic technology.It is urgent to develop new photocatalytic materials with excellent performance.Herein,two kinds of composite photocatalysts are prepared based on Layered Double Hydroxide（NiAl-LDH）.They show good photocatalytic activity in terms of CO₂reduction and pollutant degradation,providing a certain idea for solving energy and environmental problems.The specific research contents of this paper are as follows.1.g-C₃N₄hollow nanospheres were prepared through template method,in-situ polymerization and alkaline etching.Then,the urchin-like g-C₃N₄/NiAl-LDH composite was synthesized by in-situ growth of NiAl-LDH on the surface of g-C₃N₄nanospheres with Al OOH as the substrate and aluminum source by using hydrothermal process.SEM,TEM,EDS-MAPPING,XRD and FT-IR characterizations confirmed the hollow urchin structure of the composite material,the specific position of each composition and the distribution of the elements,etc.It was also confirmed that the urchin-like hollow sphere possessed a g-C₃N₄core and NiAl-LDH shell.Photocatalytic CO₂reduction was performed using the g-C₃N₄/NiAl-LDH composite photocatalyst.g-C₃N₄/NiAl-LDH showed greatly improved photocatalytic activity than that of the bare g-C₃N₄and NiAl-LDH.The yield of CO for g-C₃N₄/NiAl-LDH was 27.02μmol·g^-1·h^-1,which is 7.15 times and 4.76 times that of NiAl-LDH and g-C₃N₄,respectively.Moreover,g-C₃N₄/NiAl-LDH showed enhanced degradation capacity towards TC-HCl,the degradation rate reached 69%after irradiation of 120 min.2.The ternary metal compound precursor（MAX）was etched by HF to obtain a layered transition metal carbon（nitrogen）compound（MXene）.Then,aluminum nitrate and nickel nitrate were used as precursors,and NiAl-LDH was prepared by hydrothermal method and performed in situ.MXene was loaded to obtain a NiAl-LDH/MXene composite photocatalytic material.The structure and composition of MXene/NiAl-LDH composite were investigated by characterization of XRD and SEM.The photocatalytic performance of MXene/NiAl-LDH was evaluated by photocatalytic CO₂reduction,the optimized sample showed the CO yield of 11.82μmol·g^-1·h^-1,which was 3.12 times that of pure NiAl-LDH.