An efficient g-C3N4-decorated CdS-nanoparticle-doped Fe3O4 hybrid catalyst for an enhanced H2 evolution through photoelectrochemical water splitting

Abstract

We developed a highly efficient and stable g-C3N4-decorated CdS-nanoparticle-doped Fe3O4 nanocube catalyst, g-C3N4@CdS–Fe3O4 (gCNCSF), with a two-step solvo-thermal process in an aqueous phase. It enhanced H2 evolution via photoelectrochemical (PEC) water splitting. Melamine and isolated onion leaf extract were used to prepare g-C3N4 by calcination under an N2 atmosphere at 450 °C. Subsequently, a CdS@Fe3O4 catalyst was fabricated by doping CdS nanoparticles into the interfacial layers of Fe3O4, via a hydrothermal method, following calcination at 450 °C under N2. According to the PEC analysis, the gCNCSF catalyst exhibited a photo-current density of 0.023 mA/cm2, approximately 2.5 and 6.25 times higher than those of binary hybrids g-C3N4@CdS and CdS@Fe3O4, respectively. In addition, approximately 4.1 and 27.7 times higher performance has been recorded than those of neat CdS and g-C3N4, respectively. This was at an applied bias potential of 0.2 V vs. Ag/AgCl. The high rate of H2 evolution could be attributed to the interfacial coordination between g-C3N4 and CdS nanoparticles doped in the Fe3O4 nanocubes, which eventually promoted the bandgap-dependent interfacial charge transfer.