A versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxide and oxide nanospheres as catalytic reactors

Nowadays,multi-shelled mesoporous hollow metal oxide nanospheres have drawn a lot of attention due to their large internal space,nanometer scaled shell thickness,high specific surface area and well-defined mesopores,of which unique nanostructure endows metallic oxides with enhanced properties.In this thesis,we have studied and proposed a versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxides and oxides nanospheres,in which silica nanospheres act as sacrificial templates and the coordination interaction between metal ions and surfactant can be cooperatively amplified by using chelating ligand(ascorbic acid)as a co-template.The synthesized metal hydroxides and oxides nanospheres possess stable hollow structure,uniform spherical morphology and tunable diameter from 270 to 690 nm.All the multi-shelled mesoporous hollow metal hydroxide and metal oxide nanospheres exhibit high surface areas(up to 640 m^(2)/g).The obtained Au nanoparticles loaded composited nanospheres exhibit excellent reactivity for solvent-free aerobic oxidation of ethylbenzene with high activity(28.2%)and selectivity(87%).

Deep eutectic solvent assisted facile synthesis of low-dimensional hierarchical porous high-entropy oxides

High-entropy-oxides(HEOs),a new class of solids that contain five or more elemental species,have attracted increasing interests owing to their unique structures and fascinating physicochemical properties.However,it is a huge challenge to construct various nanostructured,especially low-dimensional nanostructured HEOs under the high temperature synthetic conditions.Herein,a facile strategy using glucose-urea deep eutectic solvent(DES)as both a solvent and the carbon source of structure-directed template is proposed for the synthesis of various HEOs with two-dimentional(2D)nanonets and one-dimentional(1D)nanowires,including rock-salt(Co,Cu,Mg,Ni,Zn)O,spinel(Co,Cr,Fe,Mn,Ni)_(3)O_(4),and perovskite La(Co,Cr,Fe,Mn,Ni)O_(3).The as-prepared HEOs possessed five or more uniformly dispersed metal elements,large specific surface areas(more than 25 m^(2)·g^(−1)),and a pure single-phase structure.In addition,high cooling rate(cooling in air or liq-N_(2)-quenching)was indispensable to obtain a single-phase rock-salt(Co,Cu,Mg,Ni,Zn)O because of phase separation caused by copper.By taking advantage of unique features of HEOs,rock-salt(Co,Cu,Mg,Ni,Zn)O can function as a promising candidate for lithium-ion batteries(LIBs)anode material,which achieved excellent cycling stability.This work provides a feasible synthetic strategy for low-dimensional hierarchical HEOs,which creates new opportunities for the stable HEOs being highly active functional materials.

Multistage Self-Assembly Strategy: Designed Synthesis of N-doped Mesoporous Carbon with High and Controllable Pyridine N Content for Ultrahigh Surface-Area-Normalized Capacitance

Nitrogen doping could improve the performance of carbon materials in electrocatalysis,CO_(2) adsorption,and energy storage.[1]However,the control of the doping type and the amount of nitrogen(N)-doped in carbon materials in a simple and environmentally friendly way remains challenging.Herein,we report a facile,multistage,self-assembly strategy for the synthesis of two-dimensional N-doped mesoporous carbon(2D NMC)by using graphene oxide(GO)as a structure-directing agent.The resultant 2D GO@NMCs rendered quantitatively controllable mesopores(8–25 nm).The 2D GO@NMCs rendered quantitatively controllablemesopores(8–25nm),high and controllable N content(up to 19 wt%),and the percentages of pyridine and pyridone/pyrrolic N atoms were as high as 49.9%and 35.3%,respectively.Due to these unique characteristics,the fabricated 2D GO@NMCs exhibited an ultrahigh surface-areanormalized capacitance of up to 90.6μF cm−2,which was much higher than the theoretical electrochemical double-layer capacitance of activated carbon(15–25μF cm−2).Moreover,our proposed multistage self-assembly strategy is versatile,and thus,could be extended to the synthesis of one-dimensional(1D)nanotubes@NMC and zero-dimensional(0D)nanospheres@NMC materials.