Possible mechanisms of CO2 reduction by H2 via prebiotic vectorial electrochemistry.
Possible mechanisms of CO2 reduction by H2 via prebiotic vectorial electrochemistry.
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H2 通过生命起源前矢量电化学还原 CO2 的可能机制。
DOI：
10.1098/rsfs.2019.0073
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发表时间：
2019
期刊：
影响因子：
4.4
通讯作者：
Vasiliadou R
中科院分区：
文献类型：
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作者：
Vasiliadou R
产甲烷菌是一种古老的自养生物，它利用一种被称为能量转换氢化酶（Ech）的膜结合的质子驱动的Fe（Ni）S蛋白质用H2还原CO2形成生物质。在生命的起源，地质上持续的H+梯度通过无机屏障含有Fe（Ni）S矿物理论上可以驱动CO2还原H2通过矢量化学以类似的方式Ech。原则上，H2、CO2和Fe（Ni）S矿物质的氧化还原电位的pH调节可以实现吸能反应。在这里，我们分析是否矢量电化学可以促进减少CO2的H2在碱性水热条件下使用微流控反应器。我们目前的试点数据显示，约5个pH单位的陡峭的pH梯度可以持续超过5小时的Fe（Ni）S屏障，与H+-通量跨越屏障约200万倍的速度比OH-通量。这种高通量在单个约25 nm的Fe（Ni）S纳米晶体上产生计算的3-pH单位梯度（等于180 mV），这接近于减少CO2所需的。然而，在大气压力下的溶解度差的H2限制CO2还原H2，解释了为什么有机合成到目前为止已被证明是难以捉摸的，在我们的反应器。未来将需要更高的H2浓度以促进通过益生元矢量电化学减少CO2。
Methanogens are putatively ancestral autotrophs that reduce CO2with H2to form biomass using a membrane-bound, proton-motive Fe(Ni)S protein called the energy-converting hydrogenase (Ech). At the origin of life, geologically sustained H+gradients across inorganic barriers containing Fe(Ni)S minerals could theoretically have driven CO2reduction by H2through vectorial chemistry in a similar way to Ech. pH modulation of the redox potentials of H2, CO2and Fe(Ni)S minerals could in principle enable an otherwise endergonic reaction. Here, we analyse whether vectorial electrochemistry can facilitate the reduction of CO2by H2under alkaline hydrothermal conditions using a microfluidic reactor. We present pilot data showing that steep pH gradients of approximately 5 pH units can be sustained over greater than 5 h across Fe(Ni)S barriers, with H+-flux across the barrier about two million-fold faster than OH–-flux. This high flux produces a calculated 3-pH unit-gradient (equating to 180 mV) across single approximately 25-nm Fe(Ni)S nanocrystals, which is close to that required to reduce CO2. However, the poor solubility of H2at atmospheric pressure limits CO2reduction by H2, explaining why organic synthesis has so far proved elusive in our reactor. Higher H2concentration will be needed in future to facilitate CO2reduction through prebiotic vectorial electrochemistry.