Controllable Synthesis of Peryleneimide-Based Nanocrystals as Bifunctional Photocatalyst for Water Splitting

Abstract

Perylene-based organic semiconductors have been widely applied in the excellent photocatalytic hydrogen/oxygen evolution (PHE/POE) from water splitting, however, no works on their bifunctional activity are reported. Herein, the ultrathin nanosheets of one-dimensional metal-organic framework (0.5Co-PDI) with the thickness of <10 nm are successfully synthesized through adjusting the acetic acid-assisted reaction between bis(N-carboxymethyl) peryleneimide(H2PDI) and Co(NO3)2. Under visible-light irradiation (λ> 420 nm), the PHE rate of 71.2 mmol⸱g−1⸱h−1 can be achieved with ascorbic acid as sacrificial agent, meanwhile, the POE rate of 18.2 mmol⸱g−1⸱h−1 can be reached with AgNO3 as electron acceptor at pH= 3. The performance exceeds the reported values obtained with bifunctional single-component, even heterojunction photocatalysts. The systematical characterizations reveal that the enough exposure of (002) active facet of Co-PDI crystal with no reactive carboxyl groups should play a crucial role in the PHE process of Co-PDI with an intrinsic high POE activity. As a result, 0.5Co-PDI sample not only has the suitable energy level, but also enough exhibits the structure advantages of Co-PDI for PHE and POE processes. This work provides a new ideal to achieve highly efficient photocatalysis of overall water splitting.

Keywords: Photocatalysis, water splitting, Perylene diimide, Bifunctional photocatalyst, One-dimensional metal-organic framework, Two-dimensional nanocrystal