OER And NRR Studies Of Structure-induced Hydrophilic And Conductive ?-MnO₂ Nanonetworks

Nanowires with anisotropic morphologies have been applied in various scientific and technological areas.It is also widely employed to fabricate nanowires into highdimensional superstructures(arrays,networks etc.)to overcome the shortcomings of lowdimensional nanowires.However,typical strategies for constructing these superstructures are restricted to complicated and harsh synthetic conditions,not to mention unique 3D structures with advanced properties beyond common superstructures.Herein,we report an unusual network of ?-MnO2 nanowires with structure-induced hydrophilicity and conductivity.In the network,the nanowires are interconnected from all directions by nodes,and the 3D network structure is formed from the endless connection of nodes in a node-by-node way.The unique network structure brings about high hydrophilicity and conductivity,both of which are positive factors for an efficient electrocatalyst.Accordingly,the ?-MnO2 network was tested for electrocatalytic water oxidation and showed significantly enhanced activity compared with isolated ?-MnO2 nanowires and 3D ?-MnO2 microspheres.Through the electronic structure design,a Cu/?-MnO2 catalyst is prepared for NRR.In this dissertatio,we studied two different Mn-based OER electrocatalysts,the main content is as follows:1.An Unusual Network of ?-MnO2 Nanowires with Structure-Induced Hydrophilicity and Conductivity for Improved Electrocatalysis.Using a simple hydrothermal synthesis method,a unique ?-MnO2 nano-network was obtained by regulating variables:hydrothermal time,feed ratio of reaction raw materials,reaction temperature,and acidity of the reaction solution.The ?-MnO2 nano wire network is a three-dimensional network structure connected by nodes through low-dimensional structures.After experimental verification,the optimized ?-MnO2 has excellent mass and charge transfer capabilities,and then exhibits superior OER activity.2.?-MnO2 nanowire network supported Cu nanoparticles as electrocatalytic N2 reduction catalyst.Through the electronic structure design,a Cu/?-MnO2 catalyst with ?-MnO2 as the substrate is prepared.The ?-MnO2,as a p-type semiconductor,induces electron-deficient Cu by contacting Cu nanoparticles with Mott-schottky.This electron-deficient Cu can enhance the polarization of N2 and promote the dissociation of N?N.The surface of this electron-deficient Cu can generate strong electrostatic interaction with OH-in the electrolyte,and can inhibit the occurrence of HER competition.