摘要
目的提高阳极产氧催化剂的催化活性与稳定性,降低电解水制氢能耗。方法在含尿素、甲酰胺及三乙醇胺的有机体系电解液中,采用阴极等离子体电解沉积技术于TC4钛合金表面沉积了FeNi/N掺杂碳膜层,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、拉曼光谱仪(Raman)及X射线光电子能谱仪(XPS),对所合成材料的物相组成、形貌及表面元素价态进行表征。采用三电极体系,所合成膜层作为工作电极,铂丝与饱和甘汞电极分别作为对电极与参比电极,通过线性扫描伏安法(LSV)、塔菲尔曲线、电化学阻抗谱及计时电位法于1.0 mol/L KOH溶液中评价了所合成材料的电催化产氧活性与稳定性。结果所合成膜层物相主要由FeNi、N掺杂碳构成,表面呈粗糙多孔结构,电解沉积70min所得FeNi/N掺杂碳在10 mA/cm^(2)下的析氧过电位为0.20 V,显著低于反应10、40、100 min下所得样品,产氧性能优于贵金属IrO_(2)和RuO_(2),同时该样品呈现出较低的电荷转移电阻(1.75Ω)和塔菲尔斜率(38.3 mV/dec),以及优异的稳定性。结论膜层表面粗糙多孔结构可有效增强传质,并为电催化产氧提供丰富的活性位点,进而改善其产氧性能。此外,材料简易的制备方法及自支撑结构可简化电极制备成本,使其在电解水领域表现出潜在的应用前景。
The work aims to improve the catalytic activity and stability of the anodic electrocatalyst for oxygen evolution reaction(OER)and reduce the energy consumption of hydrogen production from water electrolysis.In this paper,FeNi/N-doped carbon coatings on TC4 titanium alloy were deposited by cathodic plasma electrolytic deposition technique in organic system electrolyte containing urea,formamide and triethanolamine.The phase composition,morphology and surface elemental valence of the synthesized materials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Raman and X-ray photoelectron spectroscopy(XPS).FeNi alloy and a spot of iron oxide was also found by XRD pattern.SEM image showed large number of pores and large particles on the coating surface were formed during cathodic plasma electrolytic oxidation,and there were many irregular pores in the coating,suggesting its porous structure.The thickness of the coating was about 145μm,and it was closely bound to the substrate.Raman confirmed the formation of carbon.The deposited carbon was from high temperature pyrolysis of organic phase while FeNi alloy was derived from anodic oxidation dissolution and subsequent cathodic reduction.The surface element composition and valent state was characterized by the XPS spectra.The surface of as-obtained sample was composed of C,O,Fe and Ni,consistent with the energy dispersive spectra(EDS)result.Fe 2p high-resolution XPS spectra showed divalent and trivalent iron on the sample surface due to the spontaneous oxidation of FeNi alloy.N doping was in the form of pyridinic N(398.6 eV),pyrrolic N(399.8 eV)and graphitic N(401.2 eV),confirmed by the C 1s high-resolution XPS spectrum.With three-electrode system,i.e.,the as-synthesized coating as the working electrode,the platinum wire and the saturated calomel electrode(SCE)as the counter and reference electrodes,respectively,the electrocatalytic activity for oxygen production and long-term stability of the as-synthesized materials were evaluated by linear sweep voltammetry(LSV),Tafel curve,electrochemical impedance spectroscopy and chronopotentiometry in 1.0 mol/L KOH solution.The phase composition of the as-synthesized coating was mainly composed of FeNi and N-doped carbon,and the surface showed rough and porous structure.The OER overpotential at 10 mA/cm^(2) of FeNi/N-doped carbon obtained by electrolytic deposition for 70 min was only 0.20 V,which was significantly lower than that obtained at 10 min,40 min and 100 min(0.22 V).More importantly,the OER performance of this sample was superior to that of the precious metals IrO_(2) and RuO_(2).Meanwhile,this sample showed lower charge transfer resistance(1.75Ω),Tafel slope(38.3 mV/dec).The overpotential of this catalyst had no obvious change even running 48000 s at 20 mA/cm2,indicating robust long-term stability.The rough and porous structure of the coating surface can effectively enhance the mass transfer and provide abundant active sites for electrocatalytic oxygen production,thus improving OER performance.Additionally,the simple preparation method and self-supporting structure of the material can simplify the preparation cost of the electrode,thus shows a potential application prospect in water electrolysis for green hydrogen production.
作者
姜艳丽
戴鹏程
王建康
夏琦兴
姚忠平
姜兆华
JIANG Yan-li;DAI Peng-cheng;WANG Jian-kang;XIA Qi-xing;YAO Zhong-ping;JIANG Zhao-hua(Department of Chemistry,Harbin University,Harbin 150086,China;School of Chemistry and Chemical Engineering,Harbin Institute of Technology,Harbin 150001,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2023年第6期88-95,共8页
Surface Technology
基金
国家自然科学基金面上项目(51571076)。
