Graphdiyne (CnH2n−2)/NiWO4 self-assembled p–n junction characterized with in situ XPS for efficient photocatalytic hydrogen production

Abstract

As is well known, how to deeply understand the charge separation and charge transfer capabilities of catalysts, as well as how to optimize these capabilities of catalysts to improve hydrogen production performance, remains a huge challenge. In recent years, a new type of carbon material graphdiyne (GDY) has been proposed. GDY acetylene has a special atomic arrangement that graphene does not have a two-dimensional network of sp2 and sp conjugated intersections makes it easier to construct active sites and improve photocatalytic ability. In addition, GDY also has the advantage of adjusting the bandgap of other catalysts and inhibiting carrier recombination, making it more prone to hydrogen evolution reactions. In addition to using mechanical ball milling to produce GDY, NiWO4 without precious metals was also prepared. The sheet-like structure of GDY in the composite catalyst provides a anchoring site and more active sites for the granular NiWO4. And the composite catalyst fully enhances the good conductivity of GDY and its unique ability to enhance electron transfer, greatly improving the ability of NiWO4 as a single substance. Through in-situ x-ray photoelectron spectrometer, it was demonstrated that a p–n heterojunction was constructed between GDY and NiWO4 in the composite catalyst, further enhancing the synergistic effect between the two, resulting in a hydrogen production rate of 90.92 μmol for the composite catalyst is 4.56 times higher than that of GDY and 4.97 times higher than that of NiWO4, respectively, and the stability of the composite catalyst is significantly higher than that of each single catalyst.