title: Mineral-assisted pathways in prebiotic synthesis: photoelectrochemical reduction of carbon(+IV) by manganese sulfide.
abstract: Photoelectrochemistry on mineral surfaces has the potential to play a central role in the prebiotic syntheses of building blocks for biomolecules. In this study, photoreduction of C(+IV) as bicarbonate is used as a probe to investigate the photoelectrochemical properties of alabandite (MnS) colloidal particles. Our experimental results show that photoreduction occurs and that formate is the initial photoproduct. A quantum efficiency of 4.2% is obtained (pH = 7.5). The quantum efficiency is temperature-independent from 298 to 328 K. In addition to formate, longer chain carbon products are also produced. Ion chromatography shows the presence of acetate and propionate. Infrared spectroscopy and mass spectrometry indicate the formation of longer chain organic molecules that contain oxygenated functional groups. Our results suggest that some prebiotic syntheses could have occurred via photoelectrochemical reactions on semiconducting minerals.
authors.affiliation: Division of Engineering and Applied Sciences, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.forename: Xiang V
authors.initials: XV
authors.lastname: Zhang
authors.forename: Scot T
authors.initials: ST
authors.lastname: Martin
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Friend
authors.forename: Martin A A
authors.initials: MA
authors.lastname: Schoonen
authors.forename: Heinrich D
authors.initials: HD
authors.lastname: Holland
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D001639:Bicarbonates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis*; D004563:Electrochemistry; D005561:Formates / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D011422:Propionates / Q000737:chemistry; D011789:Quantum Theory; D013440:Sulfides / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D001639:Bicarbonates; D002264:Carboxylic Acids; D005561:Formates; D017895:Manganese Compounds; D011422:Propionates; D013440:Sulfides; C030544:formic acid; D002244:Carbon; C041368:manganese sulfide; C029658:propionic acid; D019342:Acetic Acid