析氧反应(OER)是电解水制氢的阳极反应,其反应速度仅为阴极析氢反应(HER)速度的十分之一。为了加快反应速度,通常需要使用RuO2等贵金属催化剂,但贵金属的稀缺性及较低的催化活性限制了其发展。金属有机框架(MOFs)材料是一类非常具有发展前景的OER电催化剂,然而目前MOFs在电催化OER中的应用也面临诸多问题,例如制备过程复杂、配体价格昂贵、催化活性低等。在此,提出了一种简易的表面活性剂辅助法制备Co-Cu双金属MOF纳米片的方法,在室温下搅拌对苯二甲酸和硝酸铜、硝酸钴,十二烷基硫酸钠的混合溶液,即可得到尺寸约为100～200nm的Co-Cu MOF纳米片。通过X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电镜(TEM)等手段对材料结构进行了表征。电催化OER性能测试表明,Co-Cu MOF(nCo∶nCu=2∶1)在碱性条件下对OER反应具有优异的OER活性,达到电流密度10mA/cm2时的过电位(η10)仅为320mV,明显优于单一的Co MOF(430mV)和Cu MOF(几乎没有活性)。理论研究表明,Cu2+的加入能提高Co MOF中Co的氧化态,进而提高其OER活性。该法操作简单、原料价格便宜,适合大规模生产,具有较好的应用前景。
Oxygen evolution reaction (OER) is an anode reaction of electrocatalytic water-splitting hydrogen production,and its reaction rate is only one tenth that of the corresponding cathode hydrogen evolution reaction (HER).In this context,noble metal catalysts such as RuO2 are usually utilized to accelerate the rate.Unfortunately,the scarcity of noble metals and low catalytic activity restrict their development.Metal organic framework (MOFs) materials have been proved a kind of promising electrocatalysts for OER.Up to date,the application of MOFs in OER still face some problem,such as the complicated fabricating process,expensive ligands,and low catalytic activity.Herein,a simple surfactant-assisted method was proposed to prepare Co-Cu bimetallic MOF nanosheets.By stirring the mixed solution of terephthalic acid,copper nitrate,cobalt nitrate and sodium dodecyl sulfate at room temperature,Co-Cu MOF nanosheets with a size of about 100～200nm could be obtained.The structure of the material was characterized by XRD,XPS,SEM and TEM.The electrocatalytic OER performance was tested.The results showed that Co-Cu MOF (nCo∶nCu=2∶1) had excellent OER activity under alkaline conditions,and only 320 mV overpotential (η10) was needed to achieve the current density of 10 mA/cm2,significantly better than that of the individual Co MOF (η10=430mV) and Cu MOF (almost no activity).The further theoretical study showed that the addition of Cu2+ improved the oxidation state of Co in Co MOF,thus enhancing its OER activity.The method proposed here was simple,and the raw material needed was very cheap,which was suitable for large-scale production.The as-obtained Co-Cu MOF nanosheets had a good application prospect.
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基金资助
国家自然科学基金(81900814);浙江省重点研发计划项目(2020C03003)
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