Increasing Solar Absorption of Atomically Thin 2D Carbon Nitride Sheets for Enhanced Visible‐Light Photocatalysis

Abstract

Atomically thin 2D carbon nitride sheets (CNS) are promising materials for photocatalytic applications due to their large surface area and very short charge‐carrier diffusion distance from the bulk to the surface. However, compared to their bulk counterpart, CNS' applications always suffer from an enlarged bandgap and thus narrowed solar absorption range. Here, an approach to significantly increase solar absorption of the atomically thin CNS via fluorination followed by thermal defluorination is reported. This approach can greatly increase the visible‐light absorption of CNS by extending the absorption edge up to 578 nm. The modulated CNS loaded with Pt cocatalyst as a photocatalyst shows a superior photocatalytic hydrogen production activity under visible‐light irradiation to Pt‐CNS. Combining experimental characterization with theoretical calculations shows that this approach can introduce cyano groups into the framework of CNS as well as the accompanied nitrogen vacancies at the edges, which leads to both narrowing the bandgap and changing the charge distribution. This study will provide an effective strategy to increase solar absorption of carbon‐nitride‐based photocatalysts for solar energy conversion applications.

Large‐Size, Porous, Ultrathin NiCoP Nanosheets for Efficient Electro/Photocatalytic Water Splitting

“…[ 41 ] As for photocatalysis, an ultrathin structure is also capable of rapid transporting photo‐excited electrons and giving sufficient active sites for HER. [ 42–44 ] Considering the above merits of bi‐metal phosphide and an ultrathin 2D structure, thus, it motivates us to design an ultrathin 2D NiCoP nanosheets to achieve efficient and stable electrocatalytic and photocatalytic water splitting performances, yet it is still to report.…”

Carbon Dots–Implanted Graphitic Carbon Nitride Nanosheets for Photocatalysis: Simultaneously Manipulating Carrier Transport in Inter‐ and Intralayers

“…These shortcomings severely limit its development in the field of photocatalysis. To address these issues, various studies have focused on the synthesis of ultrathin 2D nanosheets by using fluorination followed by thermal defluorination, liquid phase exfoliation, alkaline activation with thermal exfoliation, self‐modification through successive thermal treatment, Zn‐assisted thermal treatment, and salt‐mediated synthesis . The apparent advantages of such kinds of 2D nanosheets include short diffusion length from the bulk to the interface to reduce the transfer resistance, low recombination probability of photogenerated carriers, and enlarged specific surface areas providing abundant reactive sites .…”

Thin‐Layered Photocatalysts

“…Numerous studies have confirmed that exfoliating bulk g‐C 3 N 4 with ultrathin thickness is an effective method to overcome above problems. [ 78–87 ] Meanwhile, g‐C 3 N 4 is an analogous of graphene, in which the interaction between different layers is van der Waals forces. Therefore, it is convenient to synthesize g‐C 3 N 4 with ultrathin thickness.…”

“…[ 133 ] Aside from OVs, other kind of anion vacancies (C, I, N, and S vacancies) have also been reported. [ 86,110,134,135 ]…”