Amorphous metal-organic frameworks loaded on BiVO4 photoanodes with unique internal metal-like structure for promoting photoelectrochemical water splitting

Abstract

Although ferrocene (Fc) based Metal-Organic Frameworks (MOFs) can act as oxygen evolution co-catalysts (OECs) for improvement of catalytic reactivity, the poor conductivity and lack of highly active metal sites limit its further application in photoelectrochemical (PEC) water splitting. Herein, the amorphous NiFc-MOF was grafted on BiVO4 photoanode (BiVO4@aNiFc-MOFs) for efficient PEC water splitting. This novel BiVO4@aNiFc-MOFs exhibits high current density of 4.34 mA cm−2 at 1.23 VRHE and relative low onset potential of 0.223 VRHE. The subsequent characterizations demonstrate that Ni species with metal-like state in bulk of aNiFc-MOFs form strong metal-support interaction with BiVO4, thereby promoting the interfacial charge transfer. Moreover, the surface of aNiFc-MOFs is short-range ordered with abundant coordinatively unsaturated Ni sites, creating a more favorable pathway for oxygen evolution reaction from thermodynamics. This work provides a simple method to design photoanodes with efficient OECs of amorphous MOFs for feasible PEC water splitting application.