Polyoxometalate-assistant Synthesis Of Fe-based Porous Nanotubes And Single Vanadium Atom Catalysts For Efficient Activation Of Small Molecules

Splitting water into hydrogen and oxygen has attracted a widespread attention to meet the increasing need for energy.The oxygen evolution reaction?OER?is a critical half-reaction in water-splitting.However,high overpotential in OER has become the bottleneck of water-splitting.In the past years,a series of precious-metal compound catalysts have been employed for the OER,such as RuO₂ and IrO₂.Nevertheless,the scarcity and high cost extremely limit their continuous and large scaled applications.Therefore,developping non-precious and efficient alternative catalysts is highly desirable.In addition,with the development of industrialization,sulfides,the main product produced by over consumption of fossil fuel,will cause acid precipitation and other environmental problems.The traditional desulfurization process can not meet the demand of environmental governance due to their non-recyclable absorbents and a mass of sideproduct.In these cases,it is of great significance to develop new desulfurization catalysts to solve the energy shortage and environmental pollution.Iron-based and vanadium-based catalysts play an important role in catalytic activation of small molecules with a conspicuous merit of high earth-abundance.Polyoxometalates?POMs?,a class of metal-oxygen clusters,have been successfully introduced into multiple research areas owing to their controllable nanosize,structural diversity and stability.Herein,the porous nanotubes and single atoms catalysts were synthesized by controlling the etching acidity of POMs and using POMs as the precursor,and were futher used for efficient catalytic the reaction of small molecules.The research details are as follow:1.Typically,FeOOH/FePO_x?POM-Fe-P?porous nanotubes were synthesized by using POMs as an auxiliary reagent and used for high-efficiency electrocatalytic oxygen evolution reaction.In this process,a series of?-FeOOH nanotubes were prepared by hydrothermal treatment with the assistance of POMs.The as-prepared?-FeOOH nanotubes were further phosphatized to obtain POM-Fe-P porous nanotubes.We first use the difference acidity of POMs to modulate the pore size and surface area of the POM-Fe-P nanotubes which can expose a large number of active centers during the catalysis.Benefitting from these structural features,POM-Fe-P porous nanotubes exhibit high-performance OER activity,which offer a low overpotential of 230 mV at a current density of 10 mA cm^-2 with extraordinary stability in300 h electrolysis.Such a low overpotential has exceeded the commercial catalyst?IrO₂,275mV?and most reported Fe-based catalysts under the same conditions.2.For the vanadium single atoms catalysts,we employed Na₆[V₁₀O₂₈]·16H₂O as precursor to anchor single vanadium atoms on g-C₃N₄?V@C₃N₄?by hydrothermal treatment and further carried out possessing efficiently photocatalytic desulfurization activity.In the photocatalytic desulfurization of thioanisole,V@C₃N₄ showed high activity of desulfurization with a conversation rate of 88.4%in 24 h reaction.By contrast,pure g-C₃N₄ exhibit almost bare desulfurization activity under same condition.This work sheds a new light for the preparation and application of single atoms catalysts.