Fig. 2

Photocatalytic hydrogen evolution experiments. a Amount of hydrogen evolved from reference systems without Ni²⁺, H₂A, QDs or light illumination, respectively. b Comparison of hydrogen evolution results with InP-S QDs (525 nm) and two types of CdSe-S QDs (~525 nm). c Hydrogen evolution with InP-S QDs and InP/ZnS-S QDs (abbreviated as IZ) with different excitonic absorption peaks. d Long time hydrogen evolution of InP/ZnS-S QDs (shadowed area: error range). Conditions: a 1.6 μM InP/ZnS QDs, b 1.6 μM InP-S QDs (525 nm) and CdSe-S QDs with the same absorbance at 525 nm or c 2 μmol (of molecular concentration) QDs with different absorption peak, with 0.035 mM Ni²⁺ in 6 mL of 0.2 M H₂A (pH 4.5) were illuminated with a, b LED light source (525 nm, 4 × 1 W) and c AM 1.5 simulator light; d 1.9 μM QDs (525 nm, 15 min) and 0.042 mM Ni²⁺ in 10 mL of 0.2 M H₂A (pH 4.5) with LED light source (453 nm, 0.23 W). Error bars were estimated based on the standard deviation according to two or more independent experiments