Accelerated charge transfer via a nickel tungstate modulated cadmium sulfide p-n heterojunction for photocatalytic hydrogen evolution

Improving the efficiency of charge separation is an important aspect in photocatalysis. With NiWO4 modulation, the results of the Mott-Schottky test, short fluorescence lifetime (1.87 ns), faster electron transfer rate constant (K-ET = 2.82 x 10(8) s(-1)), larger efficiency of electron injection ((inj) = 52.7%), high photocurrent response, smaller transfer resistance (R-film = 2785 cm(2)) and reaction resistance (R-ct = 1.74 cm(2)) showed that a new interface electric field was established and a more effective thermodynamic charge transfer path was formed. This evidence greatly supported the fact that the separation and transfer of space charges over CdS p-n were accelerated via NiWO4 modulation. The [CdS/NiWO4 (30%)] sample had the best H-2 production performance, namely, the maximum H-2 production in 5 hours was 757 mol, which was 7.35 times higher than that of pure CdS nanorods. Moreover, a series of characterization results also showed that the NiWO4 decorated CdS p-n heterojunction improved the efficiency of photo-generated charge separation and the SEM, XRD, TEM, EDX, XPS, UV-vis DRS, transient fluorescence, electro-chemistry etc. results were in good agreement with each other.