Pd–Ag decorated g-C3N4as an efficient photocatalyst for hydrogen production from water under direct solar light irradiation

A low visible light absorption efficiency and high recombination rate of photogenerated charge carriers are two major problems encountered in graphitic carbon nitride (g-C3N4) based photocatalysts for water splitting applications. In this work, Pd–Ag bimetallic and monometallic nanoparticles were decorated on graphitic carbon nitride by a simple chemical reduction method and evaluated for their ability to produce H2during water splitting reactions. The physical and photophysical characteristics of the as-prepared Pd–Ag/g-C3N4photocatalysts were studied by powder X-ray diffraction (PXRD), UV-visible diffuse reflection spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and steady state photoluminescence (PL). The Pd0.7–Ag0.3/g-C3N4photocatalyst with an overall metal loading of 1 wt% showed a very high H2generation rate of 1250 μmol h−1g−1, which is 1.5 and 5.7 times higher than those of the Pd/g-C3N4and Ag/g-C3N4photocatalysts, respectively. The high activity of the Pd–Ag/g-C3N4photocatalyst was attributed to the inherent property of palladium metal to quench photogenerated electrons by the Schottky barrier formation mechanism and strong visible light absorption due to the characteristic surface plasmon resonance (SPR) of silver nanoparticles along with the absorption of g-C3N4.