Colloidal quantum dots (QDs) have demonstrated great promise in artificial photosynthesis. However, the ultrasmall size hinders its controllable and effective interaction with cocatalysts. To improve the poor interparticle electronic communication between free QD and cocatalyst, we design here a self-assembled architecture of nanoparticles, QDs and Pt nanoparticles, simply jointed together by molecular polyacrylate to greatly enhance the rate and efficiency of interfacial electron transfer (ET). The enhanced interparticle electronic communication is confirmed by femtosecond transient absorption spectroscopy and X-ray transient absorption. Taking advantage of the enhanced interparticle ET with a time scale of ∼65 ps, 5.0 mL of assembled CdSe/CdS QDs/cocatalysts solution produces 94 ± 1.5 mL (4183 ± 67 μmol) of molecular H in 8 h, giving rise to an internal quantum yield of ∼65% in the first 30 min and a total turnover number of >1.64 × 10 per Pt nanoparticle. This study demonstrates that self-assembly is a promising way to improve the sluggish kinetics of the interparticle ET process, which is the key step for advanced H photosynthesis.

Semiconductor quantum dots (QDs) in conjunction with non-noble 3d-metal ions (e.g., Fe 3+ , Co 2+ , and Ni 2+ ) have emerged as an extremely efficient, facile, and cost-effective means of solar-driven hydrogen (H 2 ) evolution. However, the exact structural change of the active sites under realistic conditions remains elusive, and the mechanism of H 2 evolution behind the remarkable activity is poorly understood. Here, we successfully track the structural variation of the catalytic sites in the typical H 2 photogeneration system consisting of CdSe/CdS QDs and 3d-metal ions (i.e., Ni 2+ used here). That is, the nickel precursor of Ni(OAc) 2 changes to Ni(H 2 O) 6 2+ in neutral H 2 O and eventually transforms to Ni(OH) 2 nanosheets in alkaline media. Furthermore, the in operando spectroscopic techniques of electron paramagnetic resonance and X-ray absorption spectroscopy reveal the photoinduced transformation of Ni(OH) 2 to a defective structure [Ni x 0 /Ni 1−x (OH) 2 ], which acts as the real catalytic species of H 2 photogeneration. Density functional theory (DFT) calculations further indicate that the surface Ni-vacancies (V Ni ) on the Ni(OH) 2 nanosheets enhance the adsorption and dissociation of H 2 O molecules to enhance the local proton concentration, while the Ni 0 clusters behave as H 2 -evolution sites, thereby synergistically promoting the activity of H 2 photogeneration in alkaline media.

Visible-light-induced nanoparticle assembly consisting of quantum dots (QDs) and Pt nanoparticles (NPs) has been achieved. The assembled nanoparticle joined a single Pt nanoparticle and multiple QDs together through controllable oxidation of thiol ligands on QDs under aerobic visible light irradiation and sonication. With an optimal ratio of QDs to Pt NPs (ca. 475:1), the assembly could achieve consecutive electron transfer from photoexcited QDs to Pt NP and evolve H2 gas with a constant rate of ∼13.9 μmol h–1 from triethylamine (TEA) during 70 h, corresponding to a turnover number (TON) of 1.4 × 107 mol H2 per mol Pt NPs. Our work shows that the assembled architecture of semiconducting QDs is a promising strategy for effective and durable H2 photogeneration.

A hand-in-hand QD assembly sensitized photocathode with extended light absorption and oriented charge transfer is established for enhanced PEC water splitting, which is comparable to or even better than those external cocatalyst-assisted systems.