Preparation And Electrocatalytic Application Of Mof Derived Transition Metal/carbon Composites

Nowadays,metal-organic framework（MOF）is often employed as a sacrifice or template for nano-transition metal catalysts and their composite materials.Thanks to their high specific surface area,adjustable structure and pore size,it has attracted great interest as an emerging porous material.MOF is easily transformed into metal oxides,metal/carbon composites and porous carbon after pyrolysis treatment.Compared with individual metal oxides,MOF derivatives have a unique structure and superior conductivity,which makes MOF-derived porous materials very promising in catalytic applications.And it is found that chitosan materials are often used as carbon precursors to synthesize transition metal/carbon composites and exhibit similar structural advantages as MOF-derived materials.The main contents are as follows:（1）One new type of electrochemical sensors is synthesized through the stepwise process,including preparing nano-sized Cu（OH）₂wires by anodizing,then wrapping Cu（OH）₂nanowires with MOF,and finally calcining and oxidizing them in the air.These as-made hierarchical composites exhibit the structural characteristics of CuO_xnanowires core and Co₃O₄nanoparticles shell calcinated from the terminally attached microporous ZIF-67.This type of glucose sensor exhibits a more satisfactory sensing capability(27778μA·m M^-1·cm^-2,0.1-1300.0μM,36 n M（S/N=3）).In addition,other four types of self-supporting MOF-derived bimetallic oxides core-shell nanowire arrays on Cu foam are also prepared by adopting the similar three-step procedure,including CuO_x@Fe₂O₃,CuO_x@Ni O,CuO_x@CuO_xand CuO_x@Zn O core-shell nanowires,demonstrating the versatility of this method.These results confirm that our as-made MOF-derived bimetallic oxide based sensor of CuO_x@Co₃O₄has potential value in the preparation of non-precious metal electrochemistry sensors field.（2）Here a simple three-step method is adopted to successfully synthesize a type of hollow MOF-derived three-dimensional carbonaceous matrix that is randomly loaded with numerous FeNi₃alloy nanoparticles（NiFeC）.In this work,the NiFeC-800-5 has an excellent OER catalytic ability to achieve 10 m A·cm^-2:overpotential of 269 m V,Tafel slope of 72 m V·dec^-1,which is executed in 1.0 M KOH liquid electrolyte at room temperature.Finally,we put forward a possible mechanism to explain morphological and chemical changes of this obtained NiFeC-800-5 product,and the final carbonization temperature and pyrolysis rate have been also well explored.（3）We use highly dispersed molybdenum carbide（CF-Glu-Mo）or Co-doped FeNi carbonate hydroxide（CF-Glu-CoFeNi）to decorate the three-dimensional porous carbon foam,and the precursor is derived from Chitosan hydrogel pretreated via glutaraldehyde cross-linking.The as-prepared CF-Glu-Mo（hydrogen evolution reaction,HER）and CF-Glu-CoFeNi（oxygen evolution reaction,OER）can be used as mono-functional electrocatalysts.In this case,the robust interconnection between the metallic catalysts and the chitosan hydrogel derived carbon foam make the whole water decomposition behavior more direct and efficient,which is reasonably attributed to hierarchically porous nanostructures and intrinsically high conductivity.The full electrolyzer assembled with carbon cloth（CC）of CF-Glu-Mo/CC||CF-Glu-CoFeNi/CC can drive full alkaline water splitting 24 h by applying an additional 1.65 V at 10 m A·cm^-2.Meanwhile,this work provides a feasible approach for the development of hydrolysis electrocatalysts through the reasonable design and regulation of heterogeneous interfaces and nanostructures.