Controlling the kinetics of visible-light-induced photocatalytic performance of gold decorated graphitic carbon nitride nanocomposite using different proteins

In this work, the interaction of different proteins with two dimensional (2D) graphitic carbon nitride (GCN) nanosheets decorated with gold nanoparticles (Au NP) is reported along with their influence in controlling the visible-light-induced photocatalytic activity. The decoration of Au NP on 2D GCN nanosheets improves the photocatalytic activity as Au NP plays an important role in trapping and storing the conduction band electrons of GCN nanosheets. The structural, morphological and optical properties of Au-GCN (AGCN) nanocomposite have been investigated using scattering and spectroscopic techniques. Methylene blue (MB) dye was chosen as a representative system for the studying of visible-light-induced photocatalytic activity of AGCN nanocomposite in the presence of different proteins. Bovine serum albumin (BSA), trypsin and cytochrome C having different chain lengths and physicochemical properties were used to control the kinetics of the photocatalytic activity of GCN and AGCN nanocomposites. Due to the simultaneous competitive adsorption of MB and proteins, the photocatalytic activity of the nanocomposites got enhanced in the presence of BSA, while it got inhibited or slowed down in the presence of trypsin and cytochrome C, respectively. The observed photocatalytic activity could be correlated with the surface charges present on the proteins and the mechanistic understanding developed in this study can be beneficial in controlling the kinetics of the photocatalytic activity of semiconductor-based photo-catalysts using proteins as activators or inhibitors.