Functionalized Carbon Nanotubes Electrocatalyst Hydrogen Evolution Reaction

Hydrogen is a clean,abundant and renewable energy.Water splitting by electrolysis is an effective and simple method to produce hydrogen.Water splitting needs hydrogen evolution electrocatalysts including noble metal-based catalysts,non-noble metal-based materials,transition metal phosphides(TMPs)and metal-free electrocatalysts.Pt is the best electrocatalyst,but its high cost and low abundance limited the large scale application of these catalysts.Ni and Co are the non-noble electrocatalysts,but they suffered from corrosion and passivation.And their activity is not as good as Pt.Transitan metal phosphides were prepared and applied in hydrogen evolution reaction.Metal-free electrocatalyst such as C60(OH)8 and C3N4 obtained high catalytic activity while were challenged due to complicate synthetic process or relatively high preparation cost.Thus,it is prospective and challenging for design and fabrication of metal-free carbon-based hydrogen evolution reaction electrocatalysts.The paper mainly includes the following three parts:1-aminopropyl-3-methylimidazolium bromide functionalized multi-walled carbon nanotubes(AMIM-Br-CNTs);CNTs-supported iron phosphide(Fe PMBMG-CNTs)and ethylenediamine-functionalized carbon nanotubes(EDA-CNTs).In this paper,FT-IR?XPS?XRD and TGA have been used to investigate the catalysts performance and mechanism.The main research contents are listed as following:(1)1-aminoproply-3-methylimidazolium bromide functionalized MWCNTs(AMIM-Br-MWCNTs)and carboxylic acid-functionalized MWCNTs(MWCNTs-COOH)were prepared.1-aminopropyl-3-methylimidazolium bromide(AMIM-Br)was interacted with MWCNTs to obtain AMIM-Br-MWCNTs.These catalysts exhibits high catalytic activity toward hydrogen evolution reaction in 0.5 Maqueous sulfuric acid electrolyte with a low onset overpotential of 350 m V,a Tafel slope of 125.62 m V/dec.Also,the possible catalytic mechanism of AMIM-Br-MWCNTs for HER was investigated via Fourier transform infrared spectroscopy(FT-IR)and X-ray photoelectrospectroscopy(XPS).All the observations from experiments reveal the electrocatalytic properties of AMIM-Br-MWCNTs originated from a synergistic effect of covalent bond structure,in which AMIM-Br obtains the strongest proton adsorption ability while the MWCNTs facilitates the electron-transfer process for the proton reduction.(2)N,N-bis(4-(methoxylcarbonyl)benzyl)-N-methyl-d-glucaminumbromide(MBMGBr)was synthesized.MBMG-Br was mixed with 3-bromopropylamine to obtain N,N-bis(4-(methoxycarbonyl)benzyl)-N-methyl-d-glucaminium bromotrichoroferrate(III)(MBMG-Fe Cl3Br).Fe P(MBMG)-CNTs generated from phosphidation of N,N-bis-(4-(methoxycarbonyl)benzyl)-N-methyl-d-glucaminium bromotrichloroferrate(III)(MBMG-Fe Cl3Br)-CNTs/Na H2PO2 mixture,obtained the best HER activity with a low onset overpotential of 70 m V,a Tafel slope of 75.9m V/dec.It is found that the glucamnium cation of MBMG-Fe Cl3 Br was carbonized to generate amorphous carbon after phosphodation,which could result in the dramatically improve current densities and decreased the electrochemical impendence.(3)Carboxylic acid-functionalized MWCNTs(MWCNTs-COOH)was prepared.Ethylenediamine was interacted with MWCNTs to obtain EDA-MWCNTs.EDA-MWCNTs possess the best HER activity with an onset overpotential of 150 m V,a Tafel slope of 116 m V/dec.Also,the possible catalytic mechanism of EDA-MWCNTs for HER was investigated via Fourier transform infrared spectroscopy(FT-IR)and X-ray photoelectrospectroscopy(XPS).All the observations from experiments reveal the elctrocatalytic properties of EDA-MWCNTs originated from a synergistic effect of covalent bond structure,in which EDA obtains the strongest proton adsorption ability,while the MWCNTs facilitates the electron-transfer process for the proton reduction.