Uniform deposition of metal-organic coordination networks on BiVO4 through chemical bonding for efficient solar water splitting

Photoelectrochemical (PEC) water splitting is a promising strategy for solar energy conversion, while the sluggish water oxidation kinetics and poor stability seriously restrict its practical applications. Herein, we demonstrated a facile hydrothermal method to in situ self-assemble metal-organic coordination networks on BiVO4 for significantly improving the PEC water oxidation activity and stability. Specifically, the 4,5-Imidazoledicarboxylic acid (IA) containing rich O/N atoms readily cross-links multiple Ni/Fe ions to form IA-NiFe (IANF) coordination networks with strong coordination capacity, which could uniformly attach on BiVO4 through chemical bonding. Systematic characterizations and theoretical calculations reveal that the uniformly coated and chemically linked IANF on BiVO4 not only effectively minimizes interfacial kinetic barriers and facilitates hole transfer, but prevents BiVO4 from photocorrosion. What's more, IANF catalysts could provide plentiful active sites to decrease the OER overpotential and accelerate reaction kinetics. As expected, the BiVO4/IANF photoanode shows an outstanding photocurrent density of 5.25 mA cm-2 at 1.23 VRHE and long-term stability. This work offers a potential pathway for building highly efficient and stable PEC water splitting systems.