Tunable surface modification of a hematite photoanode by a Co(salen)-based cocatalyst for boosting photoelectrochemical performance

In this work, a water splitting photoanode composed of hematite (alpha-Fe2O3) nanorods was modified with a Co(salen)-based cocatalyst, which was proven to exhibit special photoelectrochemical (PEC) oxygen evolution activity. Co(salen) was deposited on the surface of the alpha-Fe2O3 photoanode as a precursor of the cocatalyst and then heat-treated at different temperatures. When the annealing temperature is 250 degrees C, Co(salen) transforms into Co3+ species stabilized with C-N ligands, which act as active sites and decrease the OER energy barrier for the photoelectrochemical process of the alpha-Fe2O3 photoanode. Meanwhile, the interaction between Co-C-N and Fe (Co-C-NMIDLINE HORIZONTAL ELLIPSISFe) via van der Waals force can provide a photocarrier transfer pathway to achieve a 1.7 fold higher photocurrent at 1.23 V vs. RHE and 180 mV onset potential negative shift compared to those of the pure alpha-Fe2O3 photoanode. This work demonstrates a unique surface structure of a cocatalyst created by a post synthetic strategy using a metal complex precursor containing organic ligands.