The WL pathway depends, like other cellular processes, on a proton gradient for the reduction of CO2 by molecular hydrogen using iron center proteins in the active site of enzymes working at the intersection of membranes, such as ferredoxin. Thioesters, such as Acetyl-CoA, are extremely important in prokaryotic metabolisms such as methanogens and acetogens, in transduction pathways without the participation of ATP or any other triphosphate. Furthermore, CO2 is a component of relative abundance in the primitive ocean, and H2 is a product of serpentinization reaction. Given the universality of the Acetyl-CoA pathway, such metabolism may have already existed in the Last Universal Common Ancestor (LUCA). The initial and limiting step of this metabolism, the formation of formic acid from CO2, was recently demonstrated in the laboratory in the absence of enzymes, using the mediation of metallic samples, and under hydrothermal conditions. The emphasized variant of the submarine alkaline vent theory (SAVT) has already guided experimental works that explored the proposed requisite mechanisms of early energy conversion. Recently, We recently demonstrated CO2 reduction to formate by H2, which is the first and limiting step of WL pathway, using microfluidic setups under the conditions of the early vent-ocean interface. These microfluidc studies elucidated important aspects of a possible carbon-fixation mechanism hosted in the early hydrothermal-vent interface. Specifically, they suggest an indirect electrochemical coupling of the CO2 reduction process with H2 oxidation that occur on different sides of the inorganic barrier. Herein, to better probe the mechanism, we employ macroscale reactors in our examination not only for CO2 reduction to formate, but also the first C-C bond forming step in the production of acetic acid. Thus, we aimed to simulate different conditions estimated to exist in a gradient-rich early alkaline vent scenario and investigate the effects of those variables on the limiting key steps of the Acetyl-CoA pathway using FeS minerals. The effect of the presence of Ni in the mineral structure, the thermal gradient and the occurrence of different passive and induced electrical currents were tested in order to better understand how those conditions might have contributed to CO2 fixation at early hydrothermal-vent interfaces. Beyond CO2 fixation, we also focused on other anabolic reactions in the reverse Krebs cycle (which in contemporary systems the WL pathway feeds into). Such reverse Krebs cycle reactions are also expected to have succeeded the WL pathway at the onset of life and it has previously been demonstrated in geologically plausible batch conditions. We showcase reactions from the reverse Krebs cycle (fumarate reduction to succinate) by the indirect, gradient induced electroreduction in a separated cell reactor. Moreover, we also investigate the structure and composition of FeS minerals formed by co-precipitation used in a variety of microfluidic protocols. Finally, the macroscale reactor used in this study enables electrochemical monitoring, allowing us to probe the electron-transfer mechanism for the redox reactions involving CO2 and H2 mediated by the mineral interface.