CO2 reduction driven by a pH gradient

In summary, there are two main competing hypotheses for the origin of life: the alkaline hydrothermal vent hypothesis and the intermittent terrestrial pool hypothesis. The former relies on electrochemical reactions between ocean water and the outflow of alkaline hydrothermal vents, but these reactions have yet to be demonstrated. A paper on CO2 reduction driven by a pH gradient suggests that this process may have been a possible source of reduced carbon for the first organic molecules on Earth. The study found that microfluidic pH gradients across inorganic Fe(Ni)S precipitates could drive the reduction of CO2 with H2 to formate, providing evidence for the feasibility of early-Earth alkaline hydrothermal systems to facilitate such reactions. This could have significant implications
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BillTre
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TL;DR Summary
A proposed method in which organic molecules could be produced abiotically has been demonstrated in a lab.
In the world of Origin of Life hypothesizing, there now seem to be two main competing approaches. Life originating at alkaline hydrothermal vents and an origin in intermittent terrestrial pools (exposed to periods of drying) getting outflow from volcanically heated water sources.

The alkaline hydrothermal vent hypothesis depends upon particular reactions dependent on electrochemical potential between ocean water and the outflow of the alkaline hydrothermal vents. To my knowledge, until now these reactions have not been demonstrated.

Here is a abstract of a paper I found on https://www.researchgate.net/publication/339699873_CO2_reduction_driven_by_a_pH_gradient:
All life on Earth is built of organic molecules, so the primordial sources of reduced carbon are a major open question in studies of the origin of life. A variant of the alkaline-vent theory suggests that organics could have been produced by the reduction of CO2 via H2 oxidation, facilitated by geologically sustained pH gradients. The process would be an abiotic analog—and proposed evolutionary predecessor—of the modern Wood-Ljungdahl acetyl-Co-A pathway of extant archaea and bacteria. The first energetic bottleneck of the pathway involves the endergonic reduction of CO2 with H2 to formate, which has proven elusive in low-temperature abiotic settings. Here we show the reduction of CO2 with H2 at moderate pressures (1.5 bar), driven by microfluidic pH gradients across inorganic Fe(Ni)S precipitates. Isotopic labelling with ¹³ C confirmed production of formate. Separately, deuterium ( ² H) labelling indicated that electron transfer to CO2 did not occur via direct hydrogenation with H2 . Instead, freshly deposited Fe(Ni)S precipitates appear to facilitate electron transfer in an electrochemical-cell mechanism with two distinct half-reactions. Decreasing the pH gradient significantly, or removing either H2 or the precipitate, yielded no detectable product. Our work demonstrates the feasibility of spatially separated, yet electrically coupled geochemical reactions as drivers of otherwise endergonic processes. Beyond corroborating the ability of early-Earth alkaline hydrothermal systems to couple carbon reduction to hydrogen oxidation through geologically plausible and biologically relevant mechanisms, these results may also be of significance for industrial and environmental applications, where other redox reactions could be facilitated using similarly mild approaches.

Still waiting to get a copy of the full paper, but it sounds exciting to me.
 
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1. What is "CO2 reduction driven by a pH gradient"?

"CO2 reduction driven by a pH gradient" is a process in which carbon dioxide (CO2) is converted into other forms of carbon, such as carbon monoxide (CO), through the use of a pH gradient. This process is often used in scientific research to study the effects of pH on CO2 reduction and to develop new methods for reducing CO2 emissions.

2. How does a pH gradient drive CO2 reduction?

A pH gradient is a difference in the concentration of hydrogen ions (H+) between two areas. In CO2 reduction, this gradient is used to drive a chemical reaction that converts CO2 into other forms of carbon. This reaction is typically catalyzed by a metal catalyst, such as platinum or copper, and the pH gradient provides the necessary energy for the reaction to occur.

3. What are the potential benefits of CO2 reduction driven by a pH gradient?

The potential benefits of CO2 reduction driven by a pH gradient are numerous. This process has the potential to reduce CO2 emissions and mitigate the effects of climate change. It also has potential applications in the production of alternative fuels and chemicals, as well as in the development of new renewable energy technologies.

4. What are some challenges associated with CO2 reduction driven by a pH gradient?

One of the main challenges associated with CO2 reduction driven by a pH gradient is finding an efficient and cost-effective catalyst. Many current catalysts are expensive and can be easily deactivated by impurities in the reaction mixture. Another challenge is optimizing the pH gradient and reaction conditions to achieve maximum CO2 reduction while minimizing unwanted byproducts.

5. How is CO2 reduction driven by a pH gradient being studied and applied in the scientific community?

CO2 reduction driven by a pH gradient is a topic of ongoing research in the scientific community. Scientists are studying different catalysts, reaction conditions, and methods for creating and maintaining a pH gradient. This research has potential applications in various industries, including energy production, environmental remediation, and sustainable chemistry.

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