The synergistic modification strategy of surface active sites and interface heterojunction on ZnCo2O4 effectively enhances the photocatalytic hydrogen evolution activity

Abstract

Surface and interface modification is an effective modification method to improve the separation rate of photogenerated carriers in photocatalysts. In view of this, S element with suitable hydrogen adsorption and desorption characteristics was used as the modification source to carry out sulfur-rich modification of spinel ZnCo2O4. The more matched electronegativity difference between S elements and metal elements facilitates the charge drive and the generation of new species on the surface and successfully constructs a double heterojunction with a tight interface. The composite catalyst produced by sulfur-rich modification under the appropriate ratio exhibits excellent hydrogen evolution activity, which is 9 times that of single ZnCo2O4. The improvement of photocatalytic hydrogen evolution activity is attributed to two aspects. On the one hand, the smaller electronegativity difference between the S element and the metal element promotes the generation of more covalent bonds, which can effectively guide the charge transfer. The best S-H Adsorption and desorption can enhance the surface activity. On the other hand, the construction of surface double active sites and interfacial heterojunction makes the catalyst have stronger photogenerated carrier separation rate and reduction activity. This study provides a new strategy for expanding the application of semiconductor materials in the field of photocatalysis, namely, the strategy of surface activity and interfacial heterojunction comodification.