Effect of CoB Loading Amount in gC3N4 Nanosheet in Photocatalytic Hydrogen Generation

Abstract

Noble metals, such as Pt, Ru, and Ir, have been widely used as expensive catalyst promoters to enhance the photocatalytic hydrogen evolution reaction (HER). In contrast, other cheaper catalyst promoters that can also promote high HER performance have been developed, such as metal phosphides, and metal borides. Recently, nickel boride (NiB) loaded on graphitic carbon nitride nanosheet (gCNS) has exhibited promising HER performance under visible light. Thus, this research attempted to investigate HER performance of cobalt boride (CoB) as a cocatalyst on gCNS and compare to the HER performance of NiB. The amount of CoB loading was varied from 1-11 wt%CoB-gCNS (1-11CoB-gCNS). The reaction was carried out under 300W Xenon lamp equipped with visible light filter. Triethanolamine was employed as a sacrificial agent. The best HER performance was observed for 9CoB-gCNS at 60.71 µmole/g/h of H2 evolved. This result showed a significant enhancement in HER performance, compared with that of pure gCNS, which was attributed to better photoelectrochemical properties of the photocatalyst. The light absorbance and band gap energy (from UV-Vis spectra) of 9CoB-gCNS were significantly enhanced. Additionally, the recombination rate from PL and mobility of electron from EIS were lower which support the superior HER performance of 9CoB-gCNS which was better than that of 7NiB-gCNS (51.29 µmole/g/h).