Efficient Oxygen Evolution Reaction on Polyethylene Glycol-Modified BiVO4 Photoanode by Speeding up Proton Transfer

The rate-determining step of the oxygen evolution reaction based on a semiconductor photoanode is the formation of the O-O bond. Herein, polyethylene glycol (PEG)-modified BiVO4 photoanodes are reported, in which protons can be transferred quickly due to the high proton conductivity of PEG, resulting in the acceleration of the O-O bond formation rate. These are fully demonstrated by different kinetic isotope effect values. Moreover, the open-circuit voltage (U-oc) further illustrates that PEG passivates the surface states and surface charge recombination is reduced. The composite photoanode can achieve a maximum photocurrent density of 3.64 mA cm(-2) at 1.23 V compared to 1.04 mA cm(-2) for pure BiVO4, and an onset potential of 170 mV, which is a 230 mV negative shift compared to pure BiVO4. This work provides a new strategy to accelerate water oxidation kinetics for photoanodes by speeding up the transfer of the proton and the O-O bond formation rate.

Automated summary

This study reports PEG-modified BiVO4 photoanodes, in which the high proton conductivity of PEG facilitates the fast transfer of protons, leading to accelerated formation rate of the O-O bond. The composite photoanode exhibits higher photocurrent density and a negative shift in onset potential.