摘要
Feasible construction of cathode materials with highly dispersed active sites can extend the tri‐ple‐phase boundaries,and therefore leading to enhanced electrode kinetics for CO_(2) electrolysis in solid oxide electrolysis cell(SOEC).Herein,highly dispersed nickel species with low loading(1.0 wt%)were trapped within the La_(0.8)Sr_(0.2)FeO_(3)–δ‐Ce_(0.8)Sm_(0.2)O_(2)–δvia a facial mechanical milling ap‐proach,which demonstrated excellent CO_(2) electrolysis performance.The highly dispersed nickel species can significantly alter the electronic structures of the LSF‐SDC without affecting its porous network and facilitate oxygen vacancy formation,thus greatly promote the CO_(2) electrolysis perfor‐mance.The highest current density of 1.53 A·cm^(-2) could be achieved when operated under 800℃ at 1.6 V,which is about 91%higher than the LSF‐SDC counterpart.
利用太阳能、风能等可再生清洁电能将CO_(2)催化转化为高附加值化学品或燃料,在CO_(2)转化和可再生电能存储方面表现出极具潜力的应用前景.高温固体氧化物电解池(SOEC)可将CO_(2)电催化还原为CO,具有能量效率高、成本低等优点.目前,钙钛矿氧化物已被广泛应用于SOEC电解CO_(2)的阴极材料,但存在电极催化活性低等问题,因而限制其规模化发展和应用.通常采用浸渍、原位溶出或掺杂等策略引入大量活性中心以提升钙钛矿氧化物电极性能.然而,这些策略仍然面临一些挑战,如浸渍法易引入大颗粒物种而堵塞气体传输通道,原位溶出法能耗较大且析出量较少,掺杂法调控活性幅度有限.因此,发展新型简便方法以合理构建具有高度分散活性位点的阴极材料,可有效拓展电化学三相反应界面,进而加快SOEC高温电解CO_(2)的电极动力学速率.本文采用机械研磨法将1.0%NiO高度分散于La_(0.8)Sr_(0.2)FeO_(3)–δ-Ce_(0.8)Sm_(0.2)O_(2)–δ(Ni-LSF-SDC)表面,用作SOEC阴极材料进行CO_(2)电解.扫描电子显微镜(SEM)、透射电子显微镜、扫描透射电子显微镜(STEM)和X射线衍射等结构表征表明,低载量的Ni物种高度分散在LSF-SDC表面,并不会堵塞载体的多孔网络结构,且与钙钛矿镧锶铁(LSF)具有更好的亲和性.X射线光电子能谱和程序升温脱附结果表明,高度分散的Ni物种改善了LSF-SDC的电子结构,不仅提升了体系中电子对的含量,还在体系中形成大量氧空位,显著提升了荷质传递效率.当Ni-LSF-SDC作为SOEC阴极时,在800℃,1.6 V时,CO_(2)电解电流密度最高达到1.53 A·cm^(-2),比未经过Ni修饰的LSF-SDC阴极提高了约91%.同时Ni-LSF-SDC阴极表现出较高的稳定性,在800℃和1.2 V下稳定运行66 h后有微弱的性能衰减,电流衰减率为0.85 mA·cm^(-2)·h^(-1).对稳定性测试后电解池的电极涂覆层截面进行SEM和STEM表征,结果表明,电极表面有少量极小的N
基金
国家自然科学基金(22072146,22005045)
中国科学院洁净能源创新研究院合作基金(DNL201923)
中央高校业务基金(2232020D-07)
东华大学青年教师科研启动经费.
