Effect of precursor on the hydrogen evolution activity and recyclability of Pd-Supported graphitic carbon nitride

The examination of graphitic carbon nitride (GCN) synthesis and its catalytic activity in hydrogen production from potassium formate was done as a function of the precursor selection. Four different precursors were assessed, namely urea, dicyandiamide, melamine and thiourea. The catalytic activity of the catalysts fabricated from different GCN precursors and palladium (Pd) was compared. The catalyst prepared from dicyandiamide, Pd-GCN(D), was found to be the most active of the four precursors tested during the first reaction cycle. Nonetheless, the catalyst prepared from urea, Pd-GCN(U), has been attributed by us as the preferred catalyst due to its excellent catalytic activity as well as its phenomenal stability over multiple cycles, which was not observed for the other three catalysts. The better catalytic activity of Pd-GCN(U) is correlated to the high surface area and pore volume of the material. Both the GCN and Pd-GCN samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, Brunauer-Emmett-Teller methods, scanning tunneling electron microscopy, and X-ray photoelectron spectroscopy.