Incorporating Ni-Polyoxometalate into the S-Scheme Heterojunction to Accelerate Charge Separation and Resist Photocorrosion for Promoting Photocatalytic Activity and Stability.

The emerging polyoxometalate (POM) nanomaterials are transition metal oxygen anion clusters with d 0 electronic configurations, which could be attractive and potential photocatalysts. Hence, a nickel (Ni)-substituted polyoxometalate K 6 Na 4 [Ni 4 (H 2 O) 2 (PW 9 O 34 ) 2 ]·32H 2 O (Ni 4 POM)-incorporating step (S)-scheme heterojunction was developed to promote photocatalytic activity and stability in H 2 and H 2 O 2 production. The multielectron transfer through variable valence metal centers in Ni 4 POM would facilitate the recombination of invalid charges through the S-scheme pathway. Moreover, incorporating Ni 4 POM into the S-scheme heterojunction can broaden the light absorption range and meanwhile lead to resistance to photocorrosion to promote the optical and chemical stability of Cd 0.5 Zn 0.5 S (CZS). The optimized CZSNi-70 exhibited a H 2 evolution rate of 42.32 mmol g -1 h -1 under visible-light irradiation with an apparent quantum yield of 32.27% at 420 nm and a H 2 O 2 production rate of 295.4 μmol L -1 h -1 under 420 nm light-emitting diode irradiation. This work can provide a new view for the development of transition metal-substituted POM-based stable and efficient S-scheme photocatalysts.