Lattice Mn2+ doped CdSe/CdS quantum dots for high-performance photoelectrochemical hydrogen evolution

Colloidal core/shell quantum dots (QDs) have emerged as a promising light absorber for hydrogen (H2) production in photoelectrochemical (PEC) cells due to their attractive optoelectronic properties. However, the unfavorable band alignment and lattice mismatch of core/shell materials lead to the sluggish separation/transfer of interfacial charges, challenging the large-scale utilization of QDs-based PEC systems. Herein, we report a unique synthetic approach that incorporates metal ions (Mn2+) into the lattice of heterostructured QDs in the process of shell growth, which is verified by the combined spectroscopic and electrochemical characterizations. The PEC cell based on the optimized QDs (Mn0.03-CdSe/CdS) exhibits a superior saturated photocurrent density (∼ 18.7 mA cm−2) to that of undoped CdSe/CdS QDs (∼ 9.6 mA cm−2) under one sun illumination. The introduced intragap states (4T1) from Mn2+ ions not only reduce the conduction band offset between CdSe and CdS, but also suppress the non-radiative recombination process of photogenerated charges. This work provides a well-grounded guide to utilize metal ions for improving the transfer dynamics of photogenerated charges of heterostructured QDs in other optoelectronic devices.