Incorporating nitrogen-doped graphene oxide dots with graphene oxide sheets for stable and effective hydrogen production through photocatalytic water decomposition

• Outstanding photocatalytic water-splitting graphene oxide dot-sheet composites based on elements C, H, O, and N.
• Graphene oxide sheets acting as an electron mediator to protect the light-absorbing dots from being attacked by reaction intermediates.
• Graphene oxide sheets acting as an electron sink to facilitate charge separation in the light-absorbing dots.
• An apparent quantum yield of 16.0% in H2 production achieved by the dot-sheet composites under 420-nm light irradiation.
• The dot-sheet composites steadily catalyzing H2 evolution from a triethanolamine aqueous solution for 4 days with little activity decay.

This study proposes incorporating nitrogen-doped graphene oxide dots (NGODs) with graphene oxide (GO) sheets to form a stable and effective NGOD:GO composite for photocatalytic H2 production through water splitting under visible light illumination. Although Pt-deposited NGOD catalysts were active in the photocatalytic H2 production reaction, they were only moderately stable. Introducing GO sheets in light-absorbing NGODs effectively mediated the transfer of photogenerated electrons from the NGODs to the GO sheets. This vectorial electron transfer, confirmed by a photoluminescence spectroscopy analysis, led to the relocation of the reaction sites from the NGODs to the GO sheets, protecting the NGODs from attack by reaction intermediates. Moreover, the GO sheets acted as an electron sink, facilitating charge separation in the NGODs. When 3 wt% Pt was deposited on the developed NGOD:GO catalyst, the catalyst steadily catalyzed H2 production from a 10 vol% aqueous solution of triethanolamine under visible light illumination for 96 h, unlike a NGOD catalyst that exhibited an activity decay of 50% within 96 h. The apparent quantum yield of H2 under 420-nm light irradiation was 16.0%, demonstrating the high activity of the NGOD:GO catalyst.

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