Syngas electrosynthesis using self-supplied CO2 from photoelectrocatalytic pollutant degradation

Syngas has been synthesized via (photo) electrochemical CO2 reduction. Its amount and yield efficiency are determined the utilizable CO2. Here we show syngas electrosynthesis using self-supplied CO2, namely in situ generated CO2 from photoelectrocatalytic pollutant oxidation. In a single-chamber based two-electrode system, CO2 is produced continuously during photoelectrocatalytic phenol oxidization on the anode of TiO2 nanotubes decorated with Pd nanoparticles. Such in-situ generated CO2 is then reduced into CO at a Pd-Cu cathode. With a phenol oxidation efficiency of 87% and a faradaic efficiency of 75%, the syngas yield is as high as 339.3 mu mol. The ratio of carbon-to-hydrogen in syngas is variable from 0 to 1:10 under different current densities. The reactions for syngas generation are investigated using in-situ electrochemical infrared technique and confirmed to be C6H5OH -> CO2 -> CO2*-> COOH*-> CO*+H+-> CO+H-2. This study thus provides an approach to degrade pollutants and simultaneously utilize produced CO2 for the production of value-added chemicals like syngas.