Environment‐benign Colloidal Quantum Dots‐modified Dual Photoelectrodes for Self‐biased Photoelectrochemical Water Splitting

Photoelectrochemical (PEC) water splitting based on colloidal quantum dots (QDs) presents a promising approach for utilizing solar energy to produce green hydrogen energy. Previous research has been mainly focused on the single‐photoelectrode QDs‐PEC device operated under external bias, while the investigation of dual‐photoelectrode configuration for self‐biased QDs‐PEC system is still lacking. In this work, two types of eco‐friendly Cu‐AISe/ZnSe:Cu (CZAC) and Mn‐AIS/ZnS@Cu (MAZC) QDs were used to respectively sensitize the semiconductor n‐type TiO2 and p‐type Cu2O photoelectrodes, which acted as the photoanode and photocathode to build a heavy metal‐free QDs‐based bias‐free solar water splitting cell, yielding a maximum photocurrent density of 0.47 mA cm‐2 and a solar‐to‐hydrogen (STH) efficiency of 0.4% under 1 sun AM 1.5G illumination (100 mW cm‐2). Moreover, approximate 692 nmol of H2 and 355 nmol of O2 with molar ratio of ~2:1 was detected after two hours of continuous light illumination, demonstrating the effective overall water splitting. This work indicates a significant advancement towards the realization of a cost‐effective, efficient and “green” QDs‐based artificial solar‐to‐fuel conversion system.