Dianhydride-Modified Graphitic Carbon Nitride as a Support for Cobalt Single-Atom Photocatalysts

Graphitic carbon nitride (C3N4) has been widely explored as a photoactive support for single-atom catalysts (SACs). In this study, three different π-rich aromatic dianhydrides are employed to introduce molecularly quantized trap states into the conduction band of C3N4 to facilitate efficient charge separation, and to promote an enhanced photocatalytic CO2 reduction response. These modified C3N4 materials have been characterized structurally and spectroscopically for use as a support for Co-based SACs. In photocatalytic CO2 reduction studies, the Co SAC on naphthalene dianhydride-doped C3N4 exhibited the highest activity and selectivity toward CO production among the Co SACs tested in this work. The observed improvement in photocatalytic CO2-to-CO conversion activity correlates with trends in photoinduced charge separation, as revealed by photoluminescence spectroscopy.