A novel twin reactor for CO2 photoreduction to mimic artificial photosynthesis

One of the best routes to covert CO2 into energy and simultaneously reduce atmospheric CO2 is photosynthesis. In natural photosynthesis, the first step is water splitting in which proton is generated and O-2 is released using solar energy. The second step is the Calvin cycle in which CO2 is reduced to hydrocarbons. This study demonstrated the photocatalytic hydrogenation of CO2 by using a novel twin reactor to mimic photosynthesis process in nature. The twin reactor, which divided H-2-generating photocatalyst and O-2-generating photocatalyst in two compartments using a membrane, first achieved separate H-2 and O-2 evolution to prevent the backward reaction to form water under visible light irradiation. The generated hydrogen was then used to perform CO2 hydrogenation by CO2 reduction photocatalyst. The advantage is that CO2 hydrogenation is a spontaneous reaction based on the thermodynamics. The single photocatalyst system using Pt/CuAlGaO4 as both H-2-generating photocatalyst and CO2 reduction photocatalyst, was compared with the dual photocatalyst system using Pt/SrTiO3:Rh and Pt/CuAlGaO4 as H-2-generating photocatalyst and CO2 reduction photocatalyst, respectively, under simulated sunlight AM1.5G. The dual photocatalyst system has demonstrated photoreduction quantum efficiency (PQE) of 0.0051%, which is more than doubled the PQE of the single photocatalyst system. (c) 2012 Elsevier B.V. All rights reserved.