Effect of annealing time on chemical vapor deposition growth of 3D graphene for photoelectrochemical water splitting

Abstract

Graphene, a two-dimensional (2D) carbon material that has a zero bandgap with a symmetric band structure, has drawn extensive attention, owing to its exceptional electrical, mechanical, thermal and electron mobility properties. However, 2D graphene sheets encounter an aggregation and restacking issues, which affect the electron transport and charge separation. Therefore, a three-dimensional (3D) graphene structure has been explored to address these problems. The fabrication of 3D graphene via chemical vapor deposition (CVD) has intrigued comprehensive attention in photoelectrochemical (PEC) water splitting. It can produce high-quality graphene with a minimal defects of 3D graphene structures that can exhibit an outstanding performance for PEC water splitting. In this study, we investigated the effect of annealing time during CVD growth of 3D graphene/nickel (Ni) foam where the Ni foam was annealed with various annealing times (20–60 min). The coverage area of graphene on Ni foam has improved, based on characterization using field emission scanning electron microscope (FESEM). Raman and EDX analysis further confirmed the presence of graphene layer on Ni foam. The optimum annealing time was obtained at 50 min. The sample was tested for PEC water splitting and the current performance for 50 min annealing sample was found higher than the pure Ni foam, 596.46 mA and 429.33 mA, respectively. Thus, improved coverage area of graphene on Ni foam resulted in higher generated current that has a potential for PEC water splitting.