N-doped graphene quantum dots as charge-transfer-bridge at LaSrCoO/MoSe2 heterointerfaces for enhanced water splitting

ABSTR A C T A bifunctional electrocatalyst interface requires superior charge transfer and good electrical conductivity to produce a water splitting reaction that is overall efficient and stable. In the context of engineering the interfacial band alignment, we demonstrate a novel and straightforward approach to control the electrochemical activity of the bifunctional catalysts with precision by bridging conductive N-doped graphene quantum dots (N-GQDs, 2-3 nm) between La0.5Sr0.5CoO3-delta (LSC) and MoSe2 interfaces. The N-GQDs govern the charge transfer process at the interface, exhibiting higher Co3+ cations and metallic 1 T-MoSe2 phase-transition compared to those of LSC and LSC-MoSe2 composites. As a result, the optimized LSC-N-GQDs-MoSe2 electrocatalyst possessed a lower over -potential, Tafel slope, and charge transfer resistance in HER and OER than pure and LSC-MoSe2 electrocatalysts in an alkaline solution. The Tafel slopes (64 mV & BULL;dec(-1) and 51 mV & BULL;dec(-1) for HER and OER respectively) are smaller than those of current solutions that are commercially available, showing a higher performance at a high current density of 500 mA & BULL;cm(-2) with a long-term 24 h stability test. The key design of the current study is based on conductive bridging in the bifunctional catalyst to improve the interfacial charge transfer and electrochemical reaction.

Automated summary

This study demonstrates a novel approach to control the electrochemical activity of bifunctional catalysts by bridging conductive N-doped graphene quantum dots (N-GQDs) between La0.5Sr0.5CoO3-delta (LSC) and MoSe2 interfaces. The introduced N-GQDs improve the charge transfer process at the interface and enhance the overall performance of the electrocatalyst.