Carbon quantum dots (CQDs) modified α-Fe2O3/BiVO4 heterojunction photoanode for enhancing photoelectrochemical water splitting

The design of photoanode materials to achieve efficient water splitting is a current research hotspot in photoelectrochemical (PEC). In this work, we designed and prepared an α-Fe 2 O 3 /BiVO 4 heterostructure modified by carbon quantum dots ((α-Fe 2 O 3 /BiVO 4 /CQDs)) as the photoanode. The modification of CQDs can broaden the sunlight absorption ability and dramatically enhance the water oxidation kinetics of α-Fe 2 O 3 /BiVO 4 /CQDs. The optimized photoanode demonstrated a photocurrent density of 1.32 mA·cm −2 at 1.23 V vs. RHE, which is 2.2 times than pristine α-Fe 2 O 3 (0.6 mA·cm −2 ) photoanode. The IPCE value above 29.4 % at 400 nm, and the onset potential is negatively shifted by 243 mV for α-Fe 2 O 3 /BiVO 4 /CQDs. The improved performance is mainly due to the α-Fe 2 O 3 /BiVO 4 heterojunction to achieve effective separation of photogenerated carriers in the bulk phase and CQDs to improve light utilisation and OER kinetics of the photoanode.