Current control and second protometabolic step. To simulate and investigate specific electrochemical conditions on the vent-ocean interface, experiments were performed in the blank reactions: This reaction was performed in a single compartment (not the separated cell used for electrochemical reactions). c Sample taken from vent side rather than ocean side. Otherwise, same as a conditions n.d. : None detected range of conditions that is expected to exist in natural scenarios. A series of potentiostat-induced experiments were conducted under two conditions under fixated current (Table ): -10 nA (nanoamp), and -10 μA (microamp). The magnitude of nanoamp was estimated to be the same of the spontaneouscondition experiment (Fig ). We also tested two conditions under fixated voltage: -500 mV and -2.0 V (Table ). Hundreds of millivolts is a range that is also detected on natural hydrothermal systems and is estimated to have existed in early hydrothermal scenarios. All the referred conditions were set considering the mineral in the ocean side as the working electrode.