Boosting the photogenerated hole separation and injection of Ti-Fe2O3 by co-modifying carbon quantum dots and NiFe layered double hydroxide

Hematite (α-Fe2O3) as a photoanode material has attracted widespread attention in photoelectrochemical (PEC) water oxidation reaction. However, its performance is still impeded by the severe recombination of photogenerated charges in the bulk photoanode and at the photoanode/electrolyte interface. Herein, we have fabricated an integrated photoanode consisted of Ti doped α-Fe2O3 (Ti-Fe2O3), carbon quantum dots (CQDs) and NiFe layered double hydroxide (NiFe-LDH), aiming at improving the injection efficiency as well as the separation efficiency. The results demonstrate the appearance of CQDs in NiFe-LDH/C/Ti-Fe2O3 improves the photogenerated hole extraction from Ti-Fe2O3 to NiFe-LDH, while NiFe-LDH as a cocatalyst guarantees the rapid transfer of photogenerated holes at the photoanode/electrolyte interface. Under the synergistic effect of CQDs and NiFe-LDH, NiFe-LDH/C/Ti-Fe2O3 exhibits a stable photocurrent density of 2.89 mA/cm2 at 1.23 V vs. RHE, which is much higher than that of Ti-Fe2O3.