Graphene Enhanced Photo‐Electrochemical Water Splitting by Diminishing Pt/p‐Si Photocathode Interfacial Barrier

Abstract Converting solar energy into hydrogen by photo‐electrochemical cells is believed to be one of the most promising strategies to acquire clean energy. However, one barricade for further improving the performance of the photocathode system is flattening of the Schottky barrier formed at the interface between the p‐type photo‐absorber and metal co‐catalyst (e. g. Pt/p‐Si) due to the mismatch of their Fermi levels. Here, we present a facile way of making photocathodes by transferring high‐quality chemical vapor deposition (CVD) graphene onto p‐type Si as a buffer layer, which can effectively diminish the Pt/p‐Si interfacial barrier and promote charge separation efficiency, hence, improving the photo‐electrochemical performance of such a device for hydrogen generation. The measured photocurrent density is 3.9 times higher than that achieved without graphene buffer. This approach offers a novel route to decrease the Pt/p‐Si interfacial barrier for developing highly efficient solar conversion systems in the future. It can easily be extended to many other photocathode systems.