Tailoring Eco-Friendly Colloidal Quantum Dots for Photoelectrochemical Hydrogen Generation

A photoelectrochemical (PEC) cell is able to realize effective solar-to-hydrogen energy conversion from water by using the semiconductor photoelectrode. Semiconducting colloidal quantum dots (QDs) with captivating features of size-tunable optoelectronic properties and broad light absorption are regarded as promising photosensitizers in solar-driven PEC systems. Up to now, different types of QDs have been developed to achieve high-efficiency PEC H-2 generation, while the majority of state-of-the-art QDs-PEC systems are still fabricated from QDs consisting of heavy metals (e.g., Cd and Pb), which are extremely harmful to the human health and natural environment. In this context, substantial efforts have been made to mitigate the usage of highly toxic heavy metals and concurrently promote the development of alternative environment-friendly QDs with comparable features. This review presents recent advances of solar-driven PEC devices based on several typical environment-friendly QDs (e.g., carbon QDs, I-III-VI QDs and III-V QDs). A variety of techniques (e.g., shell thickness tuning, alloying/doping, and ligands exchange, etc.) to engineer these QD's optoelectronic properties and achieve high-efficiency PEC H(2 )production are thoroughly discussed. Furthermore, the critical challenges and future perspectives of advanced eco-friendly QDs-PEC systems in terms of QDs' synthesis, photo-induced charge kinetics, and operation stability/efficiency are briefly proposed.

Automated summary

A photoelectrochemical (PEC) cell using semiconductor photoelectrode shows great potential in converting solar energy into hydrogen. However, the use of heavy metal quantum dots (QDs) in current PEC systems poses risks to human health and the environment. This review discusses recent advances in solar-driven PEC devices based on environmentally friendly QDs, and suggests future research directions to tackle the challenges related to synthesis, charge kinetics, and operational stability/efficiency of advanced eco-friendly QDs-PEC systems.