Colloidal thick-shell pyramidal quantum dots for efficient hydrogen production

Colloidal semiconductor quantum dots (QDs) have attracted a great attention for their potential applications in optoelectronic devices, such as water splitting, luminescent solar concentrators, and solar cells, because of their size/shape/composition-dependent optoelectronic properties. However, the fast electron-hole (e-h) recombination and slow charge separation of QDs limit their applications as light absorbers in high-efficiency optoelectronic devices. Here, we synthesized thick-shell CdSe/CdSexS1-x/CdS QDs with pyramidal shape, which exhibit a quantum yield of similar to 15%, with a long radiative lifetime up to similar to 100 ns due to the spatial separation of the e/h wavefunction and significantly broadened light absorption toward the 500-700 nm range, compared to CdSe/CdS unalloyed QDs. As a proof-of-concept, the pyramidal QDs are applied as light absorbers in a photo-electrochemical (PEC) system, leading to a saturated photocurrent density of similar to 12 mA/cm(2) (with a H-2 generation rate of 90 mL cm(-2) day(-1)), which is a record for thick-shell QD-based photoelectrodes in PEC hydrogen generation. Core/thick-shell QDs hold great potential for breakthrough developments in the field of QD-based optoelectronic devices.