Modulating water oxidation kinetics utilizing h-BN quantum dots as an efficient hole extractor on fluorine doped hematite photoanode

Abstract

The sluggish water oxidation kinetics in hematite photoanode is dominated by unfavorable recombination of photogenerated holes which restrict the efficiency of photoelectrochemical (PEC) water splitting. Herein, we demonstrate a superior photoelectrochemical performance using boron nitride quantum dots (BNQDs), which is incorporated over fluorine doped hematite (F–Fe2O3) photoanode. An impressive carrier density of 2.08 × 1020 cm−3 is achieved, which is two orders of magnitude higher than that of the bare α-Fe2O3 photo anode, resulting in a photocurrent density of 2.24 mA cm−2 at 1.23 V vs reversible hydrogen electrode (RHE) for F–Fe2O3-BNQDs, which is six-fold higher than bare hematite. It is found that BNQD acts as an efficient hole extractor, which enhances the carrier separation on hematite surface and decreases the hole trapping probability. Present work emphasizes on two important parameters, i.e. (i) Enhancement in carrier density via fluorine doping directly onto the substrate using soluble precursor, organic Selectflour (ii) Modification with BNQDs to provide a simple, novel and effective strategy for the design and development of more efficient PEC water splitting systems.