Ambient temperature CO2 fixation to pyruvate and subsequently to citramalate over iron and nickel nanoparticles

Abstract

The chemical reactions that formed the building blocks of life at origins required catalysts, whereby the nature of those catalysts influenced the type of products that accumulated. Recent investigations have shown that at 100 °C awaruite, a Ni3Fe alloy that naturally occurs in serpentinizing systems, is an efficient catalyst for CO2 conversion to formate, acetate, and pyruvate. These products are identical with the intermediates and products of the acetyl-CoA pathway, the most ancient CO2 fixation pathway and the backbone of carbon metabolism in H2-dependent autotrophic microbes. Here, we show that Ni3Fe nanoparticles prepared via the hard-templating method catalyze the conversion of H2 and CO2 to formate, acetate and pyruvate at 25 °C under 25 bar. Furthermore, the 13C-labeled pyruvate can be further converted to acetate, parapyruvate, and citramalate over Ni, Fe, and Ni3Fe nanoparticles at room temperature within one hour. These findings strongly suggest that awaruite can catalyze both the formation of citramalate, the C5 product of pyruvate condensation with acetyl-CoA in microbial carbon metabolism, from pyruvate and the formation of pyruvate from CO2 at very moderate reaction conditions without organic catalysts. These results align well with theories for an autotrophic origin of microbial metabolism under hydrothermal vent conditions.

Alkaline vents recreated in two dimensions to study pH gradients, precipitation morphology, and molecule accumulation

“…Particularly interesting would be the integration of carbonate as occurring in modern Lost City-type vents (24,25) and sulfide. Both of them were also likely abundant on an early Earth (1-3) and are even providing promising catalytic capabilities known from highly reactive metal sulfides like Fe(Ni)S minerals (23,(52)(53)(54). So far, sulfides were not included in the system due to safety reason and the potential formation of H 2 S gas.…”

“…Also, because of that, electrochemical gradients in AVs may pose an important role by combining strongly opposing conditions (high-low pH or reduced-oxidized) for different or subsequent chemical reactions (13) in close spatial proximity and driving diffusiophoretic accumulation of dilute molecules (9) at catalytically active mineral surfaces (3,9,14). The catalytic potential of different iron sulfide minerals has been shown in recent experimental publications for the reduction of CO 2 (53,54,58) and also the effect of oxyhydroxide minerals on product selectivity in amino acid synthesis (13).…”

Direct Synthesis of Formamide from CO2 and H2O with Nickel–Iron Nitride Heterostructures under Mild Hydrothermal Conditions

“…Before each 1 H NMR measurement, liquid samples were treated with 0.01 M of K 3 PO 4 solution and centrifuged at 13 500 rpm for 15 min to minimize the paramagnetic effect coming from possibly leached metal species as it is described in our previous study. 67 NMR spectra were obtained on either a Bruker Avance Neo spectrometer operating at a field of 14.1 T ( 1 H Larmor frequency of 600 MHz) with a cryogenically cooled TCI probe for the highest sensitivity on the direct observation of 1 H. All spectra were collected at 25 °C in standard 5 mm tubes containing sample volumes of about 700 μL with the addition of 10% D 2 O (70 μL) as it was described previously. 38,67 In 1 H spectra, water suppression at 4.68 ppm was achieved using "excitation sculpting" together with "perfect echo" Journal of the American Chemical Society pubs.acs.org/JACS Article…”

Quantifying Catalysis at the Origin of Life**

“…Under pressurized batch conditions, supported silica Co afforded the transformation of CO 2 to methane, acetate and methanol, [14] Fe−Ni nanoparticles facilitated the transformation of CO 2 to formate, acetate and pyruvate, [15,16] and iron nanoparticles mediated the reduction of CO 2 with H 2 to formic acid and acetic acid [17] . Fe powder in water [18] (without another reductant) likewise facilitates this transformation, as does a variety of iron‐based minerals [19] to generate several additional reduction products (including acetate, pyruvate, and citramalate). A variety of other metal sulfides (Fe 3 S 4 , Ni 3 S 2 , FeS 2 , CuS, MoS, and CoS) can also reduce CO 2 with H 2 S as the reductant [20,21] .…”