The Design of a New Cobalt Sulfide Nanoparticle Implanted Porous Organic Polymer Nanohybrid as a Smart and Durable Water-Splitting Photoelectrocatalyst

Development of an inexpensive, efficient and robust nanohybrid catalyst as a substitute for platinum in photoelectrocatalytic hydrogen production has been considered intriguing and challenging. In this study, the design and sequential synthesis of a novel cobalt sulfide nanoparticle grafted Porous Organic Polymer nanohybrid (CoSx@POP) is reported and used as an active and durable water-splitting photoelectrocatalyst in the hydrogen evolution reaction (HER). The specific textural and relevant chemical properties of as-synthesised nanohybrid materials (Co3O4@POP &CoSx@POP) were investigated by means of XRD, XPS, FTIR, C-13 CP MAS NMR, spectroscopy, HR-TEM, HAADF-STEM with the corresponding elemental mapping, FE-SEM and nitrogen physisorption studies. CoSx@POP has been evaluated as a superior photoelectrocatalyst in HER, achieving a current density of 6.43 mA cm(-2) at 0 V versus the reversible hydrogen electrode (RHE) in a 0.5 m Na2SO4 electrolyte which outperforms its Co3O4@POP analogue. It was found that the nanohybrid CoSx@POP catalyst exhibited a substantially enhanced catalytic performance of 1.07 mu molmin(-1)cm(-2), which is considered to be ca. 10 and 1.94 times higher than that of pristine POP and CoSx, respectively. Remarkable photoelectrocatalytic activity of CoSx@POP compared to Co3O4@POP toward H-2 evolution could be attributed to intrinsic synergistic effect of CoSx and POP, leading to the formation of a unique CoSx@POP nanoarchitecture with high porosity, which permits easy diffusion of electrolyte and efficient electron transfer from POP to CoSx during hydrogen generation with a tunable bandgap, that straddles between the reduction and oxidation potential of water.