The development of high-performance oxygen evolution reaction catalysts with low iridium content is the key to the scale-up of proton exchange membrane water electrolyzer(PEMWE)for green hydrogen production.Single-sit...The development of high-performance oxygen evolution reaction catalysts with low iridium content is the key to the scale-up of proton exchange membrane water electrolyzer(PEMWE)for green hydrogen production.Single-site electrocatalysts with maximized atomic efficiency are held as promising candidates but still suffer from inadequate activity and stability in practical electrolyzer due to the low site density.Here,we proposed a NaNO_(3)-assistant thermal decomposition strategy for the preparation of high-density Ir single sites on MnO_(2)substrate(NaNO_(3)-H-Ir-MnO_(2)).Direct spectroscopic evidence suggests the inclusion of NaNO_(3) accelerates the transformation of Ir-Cl to Ir-O coordination,thus generating uniform dispersed high-density Ir single sites in the products.The optimized H-Ir-MnO_(2)demonstrates not only high intrinsic activity in a three-electrode set-up but also boosted performance in scalable PEMWE,requiring a cell voltage of only 1.74 V to attain a high current density of 2 A cm^(-2) at a low Ir loading of 0.18 mgIr cm^(-2).This work offers a new insight for enhancing the industrial practicality of Ir-based single site catalysts.展开更多
碳酸岩是自然界较为特殊的一类火成岩,由于其在上侵过程中不易受到地壳物质的混染,可以很好地保留源区原始特征,因而在揭示岩浆源区属性和地球深部碳循环等方面具有重要的研究价值。塔里木盆地西北缘阿克苏-乌什南部地区发育多条侵位到...碳酸岩是自然界较为特殊的一类火成岩,由于其在上侵过程中不易受到地壳物质的混染,可以很好地保留源区原始特征,因而在揭示岩浆源区属性和地球深部碳循环等方面具有重要的研究价值。塔里木盆地西北缘阿克苏-乌什南部地区发育多条侵位到新元古界南华系中的火成碳酸岩岩墙或岩脉。这些岩脉的锆石U-Pb测年结果显示出多个年龄峰值,其中最年轻一组(3颗)岩浆锆石的谐和加权年龄为272±4Ma,另外还有400Ma、450Ma、790Ma、850Ma等年龄峰,而这些锆石可能均为碳酸岩岩浆捕获成因。结合区域上发育大量早二叠世辉绿岩岩床及岩墙等侵入事件,推测这些碳酸岩很可能形成于早二叠世(~270Ma)。碳酸岩主要由方解石(90%以上)构成,并含少量的白云石、重晶石、天青石、赤铁矿等其它矿物,可见方解石与白云石之间明显的出溶结构以及野外宏观上碳酸岩包裹围岩等现象。元素地球化学分析显示,碳酸岩CaO含量高(44.40%~50.40%),SiO 2含量低(1.83%~7.97%);稀土元素总量很低(ΣREE=21.67×10^(-6)~91.32×10^(-6)),轻重稀土分异明显(LREE/HREE=3.90~8.40),具有中等负铕异常(δEu=0.61~0.68)和中等至弱负铈异常(δCe=0.59~0.98);大离子亲石元素Sr、Rb、Ba等相对富集,Nb、Ta、Ti等高场强元素相对亏损;稳定同位素δ13 C V-PDB值高(-2.69‰~-2.93‰)、δ18 O V-SMOW值高(17.33‰~17.86‰)。这些特征与壳源碳酸岩特征相似,而与幔源碳酸岩差别较大。Sr-Nd同位素结果显示高的(87 Sr/86 Sr)i值(0.710106~0.710558),低的εNd(t)值(-8.46~-12.80),也进一步证实碳酸岩为地壳来源。综合分析认为这些碳酸岩很可能是塔里木二叠纪大火成岩省晚期岩浆事件的组成部分,系由塔里木西北缘地幔柱减压熔融后形成高温的基性岩浆向上侵位运移时,导致下地壳的碳酸盐储库部分熔融形成碳酸岩岩浆,并沿着断裂快速向上侵位形成。本文研究不仅丰富了塔里木大火成岩省的岩石组成认识,而且有助于增进对二叠纪深部复杂壳幔作用过程的理解。展开更多
文摘The development of high-performance oxygen evolution reaction catalysts with low iridium content is the key to the scale-up of proton exchange membrane water electrolyzer(PEMWE)for green hydrogen production.Single-site electrocatalysts with maximized atomic efficiency are held as promising candidates but still suffer from inadequate activity and stability in practical electrolyzer due to the low site density.Here,we proposed a NaNO_(3)-assistant thermal decomposition strategy for the preparation of high-density Ir single sites on MnO_(2)substrate(NaNO_(3)-H-Ir-MnO_(2)).Direct spectroscopic evidence suggests the inclusion of NaNO_(3) accelerates the transformation of Ir-Cl to Ir-O coordination,thus generating uniform dispersed high-density Ir single sites in the products.The optimized H-Ir-MnO_(2)demonstrates not only high intrinsic activity in a three-electrode set-up but also boosted performance in scalable PEMWE,requiring a cell voltage of only 1.74 V to attain a high current density of 2 A cm^(-2) at a low Ir loading of 0.18 mgIr cm^(-2).This work offers a new insight for enhancing the industrial practicality of Ir-based single site catalysts.
文摘碳酸岩是自然界较为特殊的一类火成岩,由于其在上侵过程中不易受到地壳物质的混染,可以很好地保留源区原始特征,因而在揭示岩浆源区属性和地球深部碳循环等方面具有重要的研究价值。塔里木盆地西北缘阿克苏-乌什南部地区发育多条侵位到新元古界南华系中的火成碳酸岩岩墙或岩脉。这些岩脉的锆石U-Pb测年结果显示出多个年龄峰值,其中最年轻一组(3颗)岩浆锆石的谐和加权年龄为272±4Ma,另外还有400Ma、450Ma、790Ma、850Ma等年龄峰,而这些锆石可能均为碳酸岩岩浆捕获成因。结合区域上发育大量早二叠世辉绿岩岩床及岩墙等侵入事件,推测这些碳酸岩很可能形成于早二叠世(~270Ma)。碳酸岩主要由方解石(90%以上)构成,并含少量的白云石、重晶石、天青石、赤铁矿等其它矿物,可见方解石与白云石之间明显的出溶结构以及野外宏观上碳酸岩包裹围岩等现象。元素地球化学分析显示,碳酸岩CaO含量高(44.40%~50.40%),SiO 2含量低(1.83%~7.97%);稀土元素总量很低(ΣREE=21.67×10^(-6)~91.32×10^(-6)),轻重稀土分异明显(LREE/HREE=3.90~8.40),具有中等负铕异常(δEu=0.61~0.68)和中等至弱负铈异常(δCe=0.59~0.98);大离子亲石元素Sr、Rb、Ba等相对富集,Nb、Ta、Ti等高场强元素相对亏损;稳定同位素δ13 C V-PDB值高(-2.69‰~-2.93‰)、δ18 O V-SMOW值高(17.33‰~17.86‰)。这些特征与壳源碳酸岩特征相似,而与幔源碳酸岩差别较大。Sr-Nd同位素结果显示高的(87 Sr/86 Sr)i值(0.710106~0.710558),低的εNd(t)值(-8.46~-12.80),也进一步证实碳酸岩为地壳来源。综合分析认为这些碳酸岩很可能是塔里木二叠纪大火成岩省晚期岩浆事件的组成部分,系由塔里木西北缘地幔柱减压熔融后形成高温的基性岩浆向上侵位运移时,导致下地壳的碳酸盐储库部分熔融形成碳酸岩岩浆,并沿着断裂快速向上侵位形成。本文研究不仅丰富了塔里木大火成岩省的岩石组成认识,而且有助于增进对二叠纪深部复杂壳幔作用过程的理解。
