Mimicking lightning-induced electrochemistry on the early Earth

Area of Science:

• Astrobiology
• Geochemistry
• Plasma Chemistry

Background:

• The origin of life on Earth is hypothesized to involve the abiotic synthesis of organic molecules.
• Early Earth's atmosphere and geological conditions may have facilitated chemical reactions necessary for prebiotic chemistry.

Purpose of the Study:

• To investigate the potential for lightning-induced electrochemistry to produce reactive carbon- and nitrogen-containing compounds under early Earth conditions.
• To assess the role of interfaces in enhancing chemical yields for prebiotic synthesis.

Main Methods:

• A plasma electrochemical setup was designed to simulate lightning electrochemistry.
• Air-gap electrochemical reactions at air-water-ground interfaces were conducted under steady-state conditions.
• Gas-phase and interface-involved reactions were compared for yield efficiency.

Main Results:

• Significant reduction of carbon dioxide to carbon monoxide and formic acid (up to 40 moles per mole of electrons).
• Efficient fixation of atmospheric nitrogen into nitrate, nitrite, and ammonium ions (up to 3 moles per mole of electrons).
• Interface-involved reactions demonstrated higher yields than gas-phase-only reactions due to mineral participation.

Conclusions:

• Abiotic Earth conditions, particularly lightning electrochemistry at interfaces, could generate substantial amounts of reactive organic molecules.
• These reactions provided diverse chemical feedstocks crucial for the emergence and survival of early life.
• Lightning electrochemistry represents a plausible mechanism for seeding early Earth with essential prebiotic compounds.