氢能作为一种潜在的能源载体,有望取代化石燃料,解决当今社会的能源需求和环境问题.质子交换膜电解水(PEMWE)技术因其工作电流密度大、氢气纯度高和系统响应迅速等优点,能够有效地弥补可再生能源波动性等缺点,被认为是一种利用可再生能...氢能作为一种潜在的能源载体,有望取代化石燃料,解决当今社会的能源需求和环境问题.质子交换膜电解水(PEMWE)技术因其工作电流密度大、氢气纯度高和系统响应迅速等优点,能够有效地弥补可再生能源波动性等缺点,被认为是一种利用可再生能源制氢的可持续手段.但其阳极氧析出反应(OER)为四电子/质子转移过程,反应动力学缓慢,同时强氧化性和强酸性环境会对阳极催化剂的产生腐蚀,导致稳定性差,因此亟需开发高效且稳定的催化剂.研究发现,无定型氧化铱材料中的特殊缺陷结构可显著提升其催化酸性OER的活性,但该结构也会加速反应过程中铱的溶解,导致催化剂稳定性降低,严重限制了其实际应用.本文采用高价金属掺杂的策略,利用高价金属元素与氧的强成键作用,对无定型氧化铱的整体结构及活性位点起到优化且稳定的作用.首先,采用改性的亚当斯熔融法制备了金属钽掺杂的无定型氧化铱:350-Ta@IrO_(x),400-Ta@IrO_(x),450-Ta@IrO_(x)(350,400和450代表样品分别在350,400和450℃烧结),并用于催化酸性OER;作为对比,制备了无掺杂的无定型氧化铱:350-IrO_(x),400-IrO_(x)和450-IrO_(x).然后,通过扫描电子显微镜、透射电子显微镜(TEM)和X射线衍射等表征技术考察了材料的宏观形貌及微观结构.结果表明,掺杂后的350-Ta@IrO_(x)材料表面具有丰富的氧空位贡献的活性位点,且表现出多晶的超小纳米颗粒形貌.电化学测试结果表明,350-Ta@IrO_(x)具有较好的酸性OER活性,在10 mA cm-2的电流密度下,过电势仅为223 mV,在1.55 V vs.RHE的电位下质量活性为1207.4 A gIr-1,是商业二氧化铱的147.7倍.且该催化剂的稳定性比未掺杂Ta样品及商业二氧化铱有明显提升,在0.5 mol L^(-1)硫酸溶液中反应500 h后电位未发生明显变化.密度泛函理论计算结果表明,Ta掺杂与构建缺陷有利于OER决速步中水分子的亲核进攻,从而提升催化活性并降低反应过电势.为进一步研究材料在酸性OER工作状态下具有较好稳定性的原因,采用TEM和X射线光电子能谱等对反应前后的材料进行表征.结果表明,350-Ta@IrO_(x)在反应前后结构保持稳定,Ir溶解速率较未掺杂样品明显降低,证明了Ta掺杂大大提升了无定型氧化铱材料的稳定性.综上,本文发展了制备高价金属掺杂氧化铱的改性亚当斯熔融法,利用高价金属元素与氧的强成键作用,调控了铱活性位点的电子结构,同时提升了氧化铱类材料在酸性氧析出反应中的活性与稳定性,简化了此类材料的合成方式,为进一步降低质子交换膜电解水器件阳极催化剂的成本和提高其催化活性提供了新思路.展开更多
Lithium-oxygen(Li-O_(2))batteries have been regarded as an expectant successor for next-generation energy storage systems owing to their ultra-high theoretical energy density.However,the comprehensive properties of th...Lithium-oxygen(Li-O_(2))batteries have been regarded as an expectant successor for next-generation energy storage systems owing to their ultra-high theoretical energy density.However,the comprehensive properties of the commonly utilized organic salt electrolyte are still unsatisfactory,not to mention their expensive prices,which seriously hinders the practical production and application of Li-O_(2) batteries.Herein,we have proposed a low-cost all-inorganic nitrate electrolyte(LiNO_(3)-KNO_(3)-DMSO)for Li-O_(2) batteries.The inorganic nitrate electrolyte exhibits higher ionic conductivity and a wider electrochemical stability window than the organic salt electrolyte.The existence of K+can stabilize the O_(2)-intermediate,promoting the discharge process through the solution pathway with an enlarged capacity.Even at an ultra-low concentration of 0.01 M,the K+can still remain stable to promote the solution discharge process and also possess a new function of inhibiting the dendrite growth by electrostatic shielding,further enhancing the battery stability and contributing to the long cycle lifetime.As a result,in the 0.99 M LiNO_(3)-0.01 M KNO_(3)-DMSO electrolyte,the Li-O_(2) batteries exhibit prolonged cycling performance(108 cycles)and excellent rate performance(2 A·g^(-1)),significantly superior to the organic salt one.展开更多
文摘氢能作为一种潜在的能源载体,有望取代化石燃料,解决当今社会的能源需求和环境问题.质子交换膜电解水(PEMWE)技术因其工作电流密度大、氢气纯度高和系统响应迅速等优点,能够有效地弥补可再生能源波动性等缺点,被认为是一种利用可再生能源制氢的可持续手段.但其阳极氧析出反应(OER)为四电子/质子转移过程,反应动力学缓慢,同时强氧化性和强酸性环境会对阳极催化剂的产生腐蚀,导致稳定性差,因此亟需开发高效且稳定的催化剂.研究发现,无定型氧化铱材料中的特殊缺陷结构可显著提升其催化酸性OER的活性,但该结构也会加速反应过程中铱的溶解,导致催化剂稳定性降低,严重限制了其实际应用.本文采用高价金属掺杂的策略,利用高价金属元素与氧的强成键作用,对无定型氧化铱的整体结构及活性位点起到优化且稳定的作用.首先,采用改性的亚当斯熔融法制备了金属钽掺杂的无定型氧化铱:350-Ta@IrO_(x),400-Ta@IrO_(x),450-Ta@IrO_(x)(350,400和450代表样品分别在350,400和450℃烧结),并用于催化酸性OER;作为对比,制备了无掺杂的无定型氧化铱:350-IrO_(x),400-IrO_(x)和450-IrO_(x).然后,通过扫描电子显微镜、透射电子显微镜(TEM)和X射线衍射等表征技术考察了材料的宏观形貌及微观结构.结果表明,掺杂后的350-Ta@IrO_(x)材料表面具有丰富的氧空位贡献的活性位点,且表现出多晶的超小纳米颗粒形貌.电化学测试结果表明,350-Ta@IrO_(x)具有较好的酸性OER活性,在10 mA cm-2的电流密度下,过电势仅为223 mV,在1.55 V vs.RHE的电位下质量活性为1207.4 A gIr-1,是商业二氧化铱的147.7倍.且该催化剂的稳定性比未掺杂Ta样品及商业二氧化铱有明显提升,在0.5 mol L^(-1)硫酸溶液中反应500 h后电位未发生明显变化.密度泛函理论计算结果表明,Ta掺杂与构建缺陷有利于OER决速步中水分子的亲核进攻,从而提升催化活性并降低反应过电势.为进一步研究材料在酸性OER工作状态下具有较好稳定性的原因,采用TEM和X射线光电子能谱等对反应前后的材料进行表征.结果表明,350-Ta@IrO_(x)在反应前后结构保持稳定,Ir溶解速率较未掺杂样品明显降低,证明了Ta掺杂大大提升了无定型氧化铱材料的稳定性.综上,本文发展了制备高价金属掺杂氧化铱的改性亚当斯熔融法,利用高价金属元素与氧的强成键作用,调控了铱活性位点的电子结构,同时提升了氧化铱类材料在酸性氧析出反应中的活性与稳定性,简化了此类材料的合成方式,为进一步降低质子交换膜电解水器件阳极催化剂的成本和提高其催化活性提供了新思路.
基金financially supported by the National Key R&D Program of China(No.2020YFE0204500)the National Natural Science Foundation of China(Nos.52171194,52271140)+2 种基金the CAS Project for Young Scientists in Basic Research(No.YSBR-058)the Youth Innovation Promotion Association CAS(No.2020230)the National Natural Science Foundation of China Outstanding Youth Science Foundation of China(Overseas).
文摘Lithium-oxygen(Li-O_(2))batteries have been regarded as an expectant successor for next-generation energy storage systems owing to their ultra-high theoretical energy density.However,the comprehensive properties of the commonly utilized organic salt electrolyte are still unsatisfactory,not to mention their expensive prices,which seriously hinders the practical production and application of Li-O_(2) batteries.Herein,we have proposed a low-cost all-inorganic nitrate electrolyte(LiNO_(3)-KNO_(3)-DMSO)for Li-O_(2) batteries.The inorganic nitrate electrolyte exhibits higher ionic conductivity and a wider electrochemical stability window than the organic salt electrolyte.The existence of K+can stabilize the O_(2)-intermediate,promoting the discharge process through the solution pathway with an enlarged capacity.Even at an ultra-low concentration of 0.01 M,the K+can still remain stable to promote the solution discharge process and also possess a new function of inhibiting the dendrite growth by electrostatic shielding,further enhancing the battery stability and contributing to the long cycle lifetime.As a result,in the 0.99 M LiNO_(3)-0.01 M KNO_(3)-DMSO electrolyte,the Li-O_(2) batteries exhibit prolonged cycling performance(108 cycles)and excellent rate performance(2 A·g^(-1)),significantly superior to the organic salt one.
