Nitrogen-doped ZnIn2S4 and TPA multi-dimensional synergistically enhance photocatalytic hydrogen production

Abstract

To alleviate the environmental pollution and energy crisis caused by the excessive use of fossil fuels, photocatalytic water splitting to produce hydrogen is an important way to solve energy and environmental problems. Here, Nitrogen-doped ZnIn2S4 (N-ZIS) composite tungsten-based polyoxometalate (TPA) composites (denoted as N-ZIS/TPA) were synthesized by a one-step solvothermal method. The introduction of N3– instead of S2− in ZIS changes the internal electron arrangement of ZIS, improves the electronegativity of ZIS, and is conducive to the surface adsorption of positively charged H*. At the same time, the impurity energy level is generated at the valence band position, which narrows the band gap and broadens the light absorption range, thereby promoting photocatalytic hydrogen production. After compounding, due to the adjustable redox properties of TPA itself, the internal W6+ part is reduced to W4+, resulting in the coexistence of W6+ and W4+ in the composite material, which fully verifies the flow of interface electrons from N-ZIS to TPA. The close contact between N-ZIS and TPA and the built-in electric field’s driving force help achieve efficient interfacial charge transfer. At the same time, W6+/W4+ redox pairs were introduced to accelerate the separation of photogenerated electrons and holes. The photocatalytic hydrogen production rate of the best sample 1N-ZIS/TPA-15 is as high as 17345.53 μmol·g−1·h−1, which is 2.92 times that of N-ZIS (5940.08 μmol·g−1·h−1) and 8.03 times that of ZIS (2159.22 μmol·g−1·h−1). This study explores the design and construction of efficient s-type heterojunctions by adjusting the energy band position of ZnIn2S4 as a new strategy in the field of photocatalytic hydrogen production.