Phosphorous Doped g-C3N4 Supported Cobalt Phthalocyanine: An Efficient Photocatalyst for Reduction of CO2 under Visible-Light Irradiation

Abstract The photoreduction of the green-house gas CO2 into carbon monoxide (CO) is a growing process due to the use of CO for the production of methanol in the Fischer-Tropsch process and the synthesis of many of the bulk chemicals. Here, we have synthesized phosphorous doped graphitic carbon nitride (P-g-C3N4) sensitized by the cobalt phthalocyanine complex for the molecular reduction of CO2 into CO under visible-light irradiation—the doping of phosphorous improved the stability as well as the harvesting of the visible region. The CoPc@P-g-C3N4 hybrid photocatalyst exhibited the highest efficiency for the photoreduction of CO2 with a high yield of 295 μmol-g-1 for CO under the experimental conditions. Also, hydrogen with low concentration was identified as a by-product under the experimental conditions. The photocatalyst had stability for six consecutive runs with negligible loss of the activity and no leaching of the cobalt content at the end of the sixth run of the photoreduction experiment. The stability of the photocatalysts is an advantage, which made it a suitable candidate for the current reaction system.